DESCRIPTION
AIR COMPRESSING DEVICE FOR RAILWAY VEHICLE
Technical Field
[0001] The present invention relates to an air compressing device for a railway
vehicle, which is installed in a railway vehicle and generates compressed air that is
used in the railway vehicle.
Background Art
[0002] Railway vehicles are equipped with an air compressing device for a railway
vehicle that generates compressed air that is used in the railway vehicle. The
oil-cooled air compressor disclosed in Patent Document 1 is known to be a device that
can be used as such an air compressing device for a railway vehicle. The oil-cooled air
compressor disclosed in Patent Document 1 is configured as an air compressing device
that generates compressed air by compressing air accompanied by oil, and then
separating the oil from the compressed air. Accordingly, this air compressing device is
configured such that compression heat can be removed, and sealing and lubrication
can be performed with an oil film.
[0003] An air compressing device that generates compressed air using oil, such as
that disclosed in Patent Document 1, is provided with an oil recovery unit that has an
oil tank, an oil cooler that cools the oil recovered in the oil tank, an oil temperature
adjusting valve, and the like. The oil recovery unit is configured so as to recover oil in
the oil tank from compressed air guided thereto that was compressed along with oil in
the compressor, and is configured so as to be in communication with an oil supply path
that supplies oil to the compressor. In order to adjust the temperature of the oil (oil

temperature) in the oil tank, the oil temperature adjusting valve is configured so as to
switch to either a state of circulating oil to the oil cooler or a state of restricting the
circulation of oil, in accordance with the oil temperature in the oil tank. Note that
Patent Document 1 discloses an oil separator 3 as the aforementioned oil recovery unit,
discloses an oil cooler 5 as the aforementioned oil cooler, and discloses an oil
temperature adjusting valve 51 as the aforementioned oil temperature adjusting valve.
Also, it is disclosed that a bimetal mechanism or the like is used as the oil temperature
adjusting valve 51, which independently operates according to the oil temperature.
Citation list
Patent Document
[0004] Patent Document 1: JP H8-319976A
Disclosure of the Invention
Problem to be Solved by the Invention
[0005] In an air compressing device such as that disclosed in Patent Document 1, oil
is essential for cooling and lubrication. Also, in the case where such an air
compressing device is used as an air compressing device for a railway vehicle, checking
is periodically performed to check whether the amount of oil is at an appropriate level,
and this checking is performed after the railway vehicle runs, for example. In this
case, an operator checks the oil level using an oil level gauge that is disposed in the oil
recovery unit and can measure the oil level position in the oil tank, and replenishes the
oil as necessary.
[0006] However, in an air compressing device that generates compressed air using oil
such as that disclosed in Patent Document 1, an oil cooler and an oil temperature
adjusting valve are provided as a mechanism for adjusting the oil temperature in the

oil tank as described above. For this reason, when the operation of the air
compressing device is stopped, depending on the oil temperature and the operation
state of the oil temperature adjusting valve at the point in time when the operation is
stopped, the amount of oil recovered to the oil tank varies due to oil that remains in the
oil cooler and the path that puts the oil cooler and the oil tank in communication.
Accordingly, when the operator stops the operation of the air compressing device for a
railway vehicle in order to determine whether or not the oil needs to be replenished,
and checks the oil level position in the oil tank using the oil level gauge, the oil level
position will vary depending on the oil temperature and the operation state of the oil
temperature adjusting valve at the point in time when the operation is stopped, even if
the total amount of oil circulating in the device is the same. For this reason, there is a
problem in that it is difficult for the operator to precisely determine whether or not the
oil needs to be replenished.
[0007] In light of the above-described situation, an object of the present invention is
to provide an air compressing device for a railway vehicle that enables easily and
precisely determining whether or not oil needs to be replenished.
Means for Solving the Problem
[0008] An air compressing device for a railway vehicle according to a first invention
for achieving the above-described object is an air compressing device for a railway
vehicle that is disposed in a railway vehicle and generates compressed air that is used
in the railway vehicle, the air compressing device including: a compressor that
compresses air suctioned from the outside,' an oil supply path that supplies oil to the
compressor; an oil recovery unit that has an oil tank, separates oil from compressed air
guided thereto that was compressed along with oil in the compressor, recovers the

separated oil in the oil tank, and is in communication with the oil supply path; an oil
cooler that cools the oil recovered in the oil tank; and an oil temperature adjusting
valve that adjusts an oil temperature, being the temperature of the oil in the oil tank,
by switching to one of a state of circulating oil to the oil cooler and a state of restricting
oil circulation, in accordance with the oil temperature. Also, in the air compressing
device for a railway vehicle according to the first invention, the oil temperature
adjusting valve has: a body portion provided with a first port for communication with
the oil recovery unit, a second port for communication with an inflow portion of the oil
cooler into which oil to be cooled in the oil cooler flows from the oil recovery unit, a
third port for communication with an outflow portion of the oil cooler from which oil
cooled in the oil cooler flows, and a fourth port for communication with the compressor;
a valve plug that is disposed so as to be capable of sliding movement inside the body
portion, a position of the valve plug being switched between a circulation position at
which oil is circulated to the oil cooler by putting the first port and the second port in
communication and putting the third port and the fourth port in communication, and
a restriction position at which the circulation of oil to the oil cooler is restricted by
putting the first port in communication with the fourth port that is in communication
with the third port; a valve plug driving portion that independently operates according
to the oil temperature and drives the valve plug such that the position of the valve plug
is switched between the circulation position and the restriction position! and a
restriction position communication portion that puts the second port in communication
with the first port when the valve plug is at the restriction position.
[0009] According to this invention, in the air compressing device for a railway vehicle
configured as a device that generates compressed air by compressing air accompanied
by oil and then separating the oil from the compressed air, the oil temperature

adjusting valve causes a switch to either the state of circulating oil to the oil cooler or
the state of restricting oil circulation, in accordance with the oil temperature in the oil
tank. For this reason, when the oil temperature is a high temperature, oil cooling is
performed, and the oil temperature is adjusted. The independent valve plug driving
portion, which independently operates according to the oil temperature, switches the
position of the valve plug of the oil temperature adjusting valve between the
circulation position and the restriction position. Accordingly, when in the circulation
position state while the air compressing device for a railway vehicle is operating, the
oil recovery unit side and the inflow portion side of the oil cooler are connected, and the
outflow portion side of the oil cooler and the compressor side are connected, and thus
oil cooling is performed. When in the restriction position state, the oil recovery unit
side and the compressor side are connected, and the circulation of oil to the oil cooler is
restricted.
[0010] On the other hand, after the operation of the air compressing device for a
railway vehicle has stopped, even if the position of the valve plug is the circulation
position at the stop timing, the position of the valve plug will be switched to the
restriction position due to the operation of the independent valve plug driving portion
that accompanies a decrease in the oil temperature. At this time, the state in which
the second port and the first port are in communication is maintained since the oil
temperature adjusting valve is provided with the restriction position communication
portion. For this reason, after the operation of the air compressing device for a
railway vehicle stops, after at least a certain period of time has elapsed and the oil
temperature has decreased, the state in which the first port is in communication with
the second port and the third port is maintained. Accordingly, the state in which the
inflow portion side and the outflow portion side of the oil cooler are in communication

with the oil recovery unit side is maintained, and the operation of the compressor is
also stopped, and therefore the accumulation of oil in the oil cooler and in the path that
puts the oil cooler and the oil tank in communication is suppressed, oil is recovered in
the oil tank, and variation in the amount of recovered oil is suppressed. This
suppresses the situation in which, even when the total amount of oil circulated in the
device is the same, the oil level position varies depending on the operation state of the
oil temperature adjusting valve when operation is stopped, such that the oil level
position converges at a stable and substantially identical position when the operator
checks the oil level in the oil tank using the oil level gauge. For this reason, the
operator can easily and precisely determine whether or not the oil needs to be
replenished. Note that the restriction position communication portion may be a
mechanism that is integrally provided with the valve plug, or may be a mechanism
that is provided so as to be capable of operating independently from the valve plug.
[OOll] Accordingly, the present invention enables providing an air compressing
device for a railway vehicle that enables easily and precisely determining whether or
not oil needs to be replenished.
[0012] An air compressing device for a railway vehicle according to a second
invention is the air compressing device for a railway vehicle according to the first
invention, wherein the restriction position communication portion is provided by way
of a through-hole formed in the valve plug, and when the valve plug is at the
restriction position, one opening of the through-hole opposes the second port, and when
the valve plug is at the circulation position, the one opening of the through-hole is
blocked by a wall portion in the body portion, the wall portion being provided between
the second port and one of the third port and the fourth port.
[0013] According to this invention, the restriction position communication portion is

provided by way of a through-hole formed in the valve plug. This enables easily
constructing the restriction position communication portion with a simple structure.
Note that the one opening of the restriction position communication portion provided
by way of a through-hole is in communication with the second port only when at the
restriction position, and is blocked by the wall portion between the second port and the
third or fourth port when at the circulation position. When at the circulation position,
this prevents the through-hole serving as the restriction position communication
portion from putting the first port in communication with the third port and the fourth
port, and prevents the circulation of oil to the oil cooler from being inhibited due to the
oil recovery unit side being in communication with the outflow portion side of the oil
cooler and the compressor side.
Effects of the Invention
[0014] According to the present invention, it is possible to provide an air compressing
device for a railway vehicle that enable easily and precisely determining whether or
not oil needs to be replenished.
Brief Description of the Drawings
[0015] FIG. 1 is a system diagram schematically showing a system configuration of
an air compressing device for a railway vehicle according to an embodiment of the
present invention.
FIG. 2 is a schematic diagram for describing the flow path of oil through an oil
temperature adjusting valve in the air compressing device for a railway vehicle shown
in FIG. 1.
FIG. 3 is a diagram showing the oil temperature adjusting valve shown in FIG.

2.
FIG. 4 is a schematic diagram for describing operations of the oil temperature
adjusting valve in the air compressing device for a railway vehicle shown in FIG. 1.
FIG. 5 is a schematic diagram for describing operations of the oil temperature
adjusting valve in the air compressing device for a railway vehicle shown in FIG. 1.
Description of Embodiments
[0016] Hereinafter, an embodiment for rarrying out the present invention will be
described with reference to the drawings. Note that the present embodiment is an air
compressing device for a railway vehicle that is disposed in a railway vehicle and
generates compressed air that is used in the railway vehicle, and is widely applicable
in an air compressing device for a railway vehicle that generates compressed air by
compressing air accompanied by oil and then separating the oil from the compressed
air.
[0017] FIG. 1 is a system diagram schematically showing the system configuration of
an air compressing device for a railway vehicle 1 (referred to hereinafter as simply the
"air compressing device 1") according to an embodiment of the present invention. The
air compressing device 1 shown in FIG. 1 is disposed in a railway vehicle (not shown).
Compressed air generated in the air compressing device 1 is used in order to operate a
pneumatic device such as a braking device in a railway vehicle. Note that the air
compressing device 1 is disposed in each vehicle in the railway vehicle train, for
example.
[0018] The air compressing device 1 shown in FIG. 1 is configured so as to include a
storage case 11, a compressor 12, a compressor driving unit 13, a coupling 14, a
coupling case 15, a cooling fan 16, an after cooler 17, an air suction unit 18, a

compressed air delivery unit 19, an oil supply path 20, an oil recovery unit 21, an oil
separation element 22, a water-oil separator 23, a dehumidifier 24, an oil cooler 25, an
oil temperature adjusting valve 26, an oil level gauge 27, and the like.
[0019] The air compressing device 1 is configured as an apparatus by which
suctioned air from the air suction unit 18 is compressed by the compressor 12, cooled
by the after cooler 17, and then delivered as compressed air from the compressed air
delivery unit 19. Moreover, due to including the oil supply path 20, the oil recovery
unit 21, the oil separation element 22, the wateroil separator 23, the oil cooler 25, the
oil temperature adjusting valve 26, and the like, the air compressing device 1 is
configured as an apparatus that generates compressed air by compressing air
accompanied by oil and then separating the oil from the compressed air. Accordingly,
the air compressing device 1 is configured such that compression heat can be removed
and sealing and lubrication can be performed with an oil film. The following is a
detailed description of the constituent elements of the air compressing device 1.
[0020] The storage case 11 is provided as a box-shaped casing for accommodating the
compressor 12, the compressor driving unit 13, the coupling case 15, the cooling fan 16,
the after cooler 17, the oil supply path 20, the oil recovery unit 21, the oil separation
element 22, the wateroil separator 23, the dehumidifier 24, the oil cooler 25, and the
like. The air suction unit 18 and the compressed air delivery unit 19 are disposed on
a wall portion of the storage case 11.
[0021] The air suction unit 18 disposed on the storage case 11 is provided by way of a
mechanism for suctioning air (outside air) that is to be compressed by the compressor
12, and is provided so as to be in communication with the compressor 12. The air
suction unit 18 is provided with a suction filter 18a that suppresses the passage of dust
such as sand-dust as suctioned air passes through. Also, the compressed air delivery

unit 19 is provided by way of a mechanism for delivering compressed air that has been
cooled by the after cooler 17. This compressed air delivery unit 19 is provided by way
of a piping system that extends outward from the storage case 11 so as to supply
generated compressed air to an air tank (compressed air reservoir) (not shown) that is
disposed outside the storage case 11 and is for collecting compressed air.
[0022] Also, a filter unit 28 is disposed in a wall portion of the storage case 11 that is
located on the upstream side of the flow of cooled air generated by the cooling fan 16.
For example, the filter unit 28 is provided by way of wire mesh attached to the storage
case 11. Due to rotation of the cooling fan 16, outside air that is to become cooled air
is suctioned through the filter unit 28. Note that in FIG. 1, the flow of suctioned
outside air and the flow of dried air are shown by bold arrows that are hollow with only
outlines. Also, the flow of air that contains oil droplets, water droplets, and water
vapor is shown by bold arrows with diagonal hatching. Moreover, the flow of oil is
shown by narrow-line arrows.
[0023] The compressor 12 is configured so as to be in communication with the air
suction unit 18 and compress air that was suctioned from the outside via the air
suction unit 18. Note that the compressor 12 is configured so as to be in
communication with the air suction unit 18 via a suction valve 29 formed so as to be
integrated with the body of the compressor. The suction valve 29 is configured so as
to include a valve plug, a valve seat to/from which the valve plug can attach/detach,
and a spring that biases the valve plug in the direction of attaching to the valve seat.
When the compressor 12 operates and the compressor 12 side becomes negatively
pressurized, the valve plug is caused by outside air pressure to detach from the valve
seat against the spring force of the spring, and air is suctioned into the compressor 12.
[0024] Also, the compressor 12 is provided by way of a screw-type air compressor,

which has a pair of screws that rotate in mutually opposite directions so as to compress
air, for example. Inside the compressor body in which the screws are disposed, the air
pressure rises from the portion in communication with the suction valve 29 to the
portion in communication with the oil recovery unit 21. Note that although the
present embodiment describes the example where the compressor 12 is provided by
way of a screw-type air compressor, another configuration may be used. The
compressor 12 may be provided by way of a scroll-type air compressor, a reciprocating
air compressor, which is driven upon transmission of reciprocating driving force
obtained by the conversion of rotational driving force from the compressor driving unit
13 via a crankshaft, or the like.
[0025] The compressor driving unit 13 is provided by way of a driving mechanism
that has an electric motor 13a and drives the compressor 12 so as to rotate. Note that
although the present embodiment describes the example of the case where the
compressor driving unit 13 is provided by way of a driving mechanism provided with
only the electric motor 13a and without a speed reduction unit, another configuration
may be used. In other words, the compressor driving unit 13 may be provided by way
of a motor with a speed reducer that includes a speed reduction unit coupled to the
electric motor 13a.
[0026] The coupling 14 is configured so as to couple the compressor driving unit 13 to
the compressor 12 and transmit driving force from the compressor driving unit 13 to
the compressor 12, and the coupling 14 is provided by way of a shaft coupling, for
example. The coupling case 15 is provided by way of a box-shaped body that
accommodates the coupling 14. Also, the coupling case 15 is disposed between the
compressor 12 and the compressor driving unit 13, and is joined to the compressor 12
and the compressor driving unit 13.

[0027] The cooling fen 16 is attached to the compressor driving unit 13, on the end
portion thereof that is on the side opposite to the side to which the coupling 15 is
coupled. The cooling fan 16 is provided by way of an axial flow fan, which is
configured so as to include a propeller unit and a tube-shaped case unit (not shown)
that is disposed in the periphery of the propeller unit. The cooling fan 16 is also
disposed such that driving force from the rotation shaft of the electric motor 13a is
transmitted to the propeller unit on the side opposite to the coupling side. In this way,
the cooling fan 16 is configured so as to be driven by driving force from the electric
motor 13a so as to rotate, and thus generate a flow of cooled air using the air suctioned
from the filter unit 28. Note that although the present embodiment describes the
example of the case where the cooling fan 16 is an axial flow fan, another configuration
may be used, and it is possible to use another type of cooling fan such as a sirocco fan.
[0028] The after cooler 17 is provided by way of a heat exchanger that cools
compressed air in which compression heat remains due to being compressed by the
compressor 12. This after cooler 17 is disposed on the upstream side of the cooling fan
16 in terms of the flow of cooled air generated by the cooling fan 16 (note that FIG. 1 is
a schematic system diagram and does not specify the arrangement of the after cooler
17 in the storage case 11). Accordingly, the after cooler 17 is cooled from the outside
by cooled air generated by the cooling fan 16, and thus compressed air passing through
the inside of the after cooler 17 is cooled. Note that the after cooler 17 is formed so as
to be integrally joined with the oil cooler 25. Also, the after cooler 17 may be disposed
on the downstream side of the cooling fan 16 in terms of the flow of cooled air
generated by the cooling fan 16.
[0029] The oil recovery unit 21 is configured so as to include an oil-containing
compressed air discharge path 21a and an oil tank 21b. The oil-a)nteining

compressed air discharge path 21a is provided by way of a path that puts the
compressor 12 and the oil tank 21b in communication. Compressed air that has been
compressed along with oil in the compressor 12 is guided to the oil tank 21b via the
on-containing compressed air discharge path 21a, and oil discharged from the
on-containing compressed air discharge path 21a along with the compressed air is
recovered in the oil tank 21b.
[0030] Also, a separator 30 is disposed in a discharge portion of the on-containing
compressed air discharge path 21a that is inside the oil tank 21b. When the
compressed air accompanied by oil that is guided through the on-containing
compressed air discharge path 21a is discharged from the discharge portion thereof, oil
is separated from the compressed air by the separator 30, thereafter falling due to
gravity while scattering inside the oil tank 21b, and thus is recovered in the oil tank
21b. Recovered oil 31 is thus collected in the oil tank 21b.
[0031] The oil level gauge 27 is disposed on the oil tank 21b of the oil recovery unit 21.
The oil level gauge 27 is provided by way of a measuring means capable of measuring
the oil level position of the oil 31 in the oil tank 21b. The operator who is to check the
oil level in the oil tank 21b uses the oil level gauge 27 to check the oil level position.
Note that various modes of oil level gauges can be used as the oil level gauge 27. For
example, it is possible to use an oil level gauge provided by way of a window portion
that allows the operator to visually check the oil level position from the outside, a
float-type oil level gauge, an ultrasonic oil level gauge, a pressure-type oil level gauge,
or the like.
[0032] Also, a temperature switch 32 is disposed in the oil tank 21b as a temperature
sensor that detects the temperature (oil temperature) of the oil 31 in the oil tank 21b.
This temperature switch 32 is provided by way of a temperature sensor that outputs a

signal for forcibly stopping the device as a whole if the detected oil temperature is
higher than or equal to a predetermined upper limit temperature.
[0033] The oil supply path 20 is disposed so as to be in communication with the oil
tank 21b of the oil recovery unit 21 and the compressor 12, and is provided by way of a
path that supplies oil from the oil tank 21b to the compressor 12. The oil supply path
20 is in communication with the compressor body of the compressor 12 on the
low-pressure side where the pressure is low, which is the suction side that is in
communication with the suction valve 29. Also, the oil supply path 20 is configured so
as to be in communication with the oil tank 21b at a position lower than the oil level of
the oil 31 in the oil tank 21b. Since the oil supply path 20 is in communication with
the compressor 12 and the oil tank 21b in this way, compressed air discharged from
the on-containing compressed air discharge path 21a pushes the oil level of the oil 31
downward, and thus oil is supplied to the compressor 12 via the oil supply path 20.
Note that an oil strainer 20a is disposed as a filter element at a midpoint in the oil
supply path 20 so as to prevent foreign objects in the oil tank 21b (e.g., scum-like
substances resulting from the clumping of degraded oil) from being supplied to the
compressor 12.
[0034] The oil separation element 22 is disposed in a path that puts the oil tank 21b
of the oil recovery unit 21 and the after cooler 17 in communication, and is configured
so as to include a filter element that further separates oil from compressed air that
was compressed along with oil in the compressor 12 and then passed through the oil
recovery unit 21. Small oil droplets that were not recovered in the oil recovery unit 21
are separated from compressed air in the oil separation element 22.
[0035] Also, a compressor communication path 33 is provided so as to extend from
the oil separation element 22 toward the compressor 12 or the suction valve 29. This

compressor communication path 33 is disposed so as to put the compressor 12 in
communication with a lower portion of the oil separation element 22 inside its housing
portion, and is configured such that oil separated by the oil separation element 22 is
pushed upward by compressed air and supplied to the compressor 12. Note that a
throttle for suppressing the amount of compressed air that passes is disposed in the
compressor communication path 33.
[0036] Also, a path that puts the oil separation element 22 and the after cooler 17 in
communication is provided with a pressure-retaining check valve 34 that permits the
passage of compressed air toward the after cooler 17 when the pressure is greater than
or equal to a predetermined pressure, and a safety valve 35 for allowing compressed
air to escape to the outside when the pressure of the compressed air is greater than or
equal to a predetermined excessive pressure.
[0037] The water-oil separator 23 is disposed in a path that puts the after cooler 17
and the dehumidifier 24 in communication, and is configured so as to include multiple
filter elements that separate the water component and the oil component from
compressed air cooled by the after cooler 17. In the water-oil separator 23, the water
component is separated from compressed air, and also the minute amount of the oil
component that was not separated out in the oil separation element 22 is separated
from compressed air. Note that the water component and the like that are separated
in the water-oil separator 23 is discharged from a drain valve 36.
[0038] The dehumidifier 24 is disposed between the wateroil separator 23 and the
compressed air delivery unit 19, and is configured so as to include a filter element that
contains a desiccant for further dehumidifying compressed air from which the water
component and the oil component were separated by the wateroil separator 23, or a
filter element that performs dehumidification using hollow fiber membranes.

Compressed air delivered from the compressed air delivery unit 19 is subjected to final
dehumidification in the dehumidifier 24. Note that a path that puts the dehumidifier
24 and the compressed air delivery unit 19 in communication is provided with a check
valve 37 that allows the passage of compressed air toward the compressed air delivery
unit 19 when the pressure is greater than or equal to a predetermined pressure, in
order to prevent the backflow of compressed air from an air tank (compressed air
reservoir) (not shown).
[0039] The oil cooler 25 is provided so as to be in communication with the oil tank 21b
side and the compressor 12 side of the oil supply path 20 via the oil temperature
adjusting valve 26, and is provided by way of a heat exchanger by which oil in the oil
tank 21b can be cooled and supplied to the oil supply path 20. As previously
mentioned, the oil cooler 25 is formed so as to be integrally joined with the after cooler
17. Also, the oil cooler 25 is disposed so as to be higher than the oil recovery unit 21
on the upstream side of the cooling fan 16 in terms of the flow of cooled air (note that
FIG. 1 is a schematic system diagram and does not specify the arrangement of the oil
cooler 25 in the storage case 11). Accordingly, the oil cooler 25 is cooled from the
outside by cooled air generated by the cooling fan 16, and thus oil passing through the
inside of the oil cooler 25 is cooled. Note that the oil cooler 25 may be disposed on the
downstream side of the cooling fan 16 in terms of the flow of cooled air.
[0040] As described above, the oil cooler 25 is provided so as to be in communication
with the oil supply path 20 at two locations via the oil temperature adjusting valve 26,
namely the side in communication with the oil tank 21b and the side in
communication with the compressor 12. Accordingly, the oil cooler 25 is configured
such that oil flowing from the oil tank 21b into the oil supply path 20 is taken in from
the oil supply path 20 via the oil temperature adjusting valve 26 and a branching oil

path 38a and then cooled, and then the cooled oil is returned to the oil supply path 20
via an oil path 38b and the oil temperature adjusting valve 26. Note that the oil
returning to the oil supply path 20 after being cooled by the oil cooler 25 is caused to
flow due to the oil level of the oil 31 being pushed downward by compressed air
discharged from the on-containing compressed air discharge path 21a.
[0041] PIG. 2 is a schematic diagram for describing the flow path of oil via the oil
temperature adjusting valve 26 in the air compressing device 1, and shows the oil
temperature adjusting valve 26, the compressor 12, the oil recovery unit 21, and the oil
cooler 25. Note that the oil cooler 25 schematically shown as an example in the
schematic diagram of FIG. 2 is an oil cooler 25 having a structure according to which
oil flows in, is cooled while flowing over a partition wall 25a, and then flows out. Also,
FIG. 2 shows the oil temperature adjusting valve 26 in a cross-sectional view, and also
shows the outer shape of some of the elements.
[0042] The following is a detailed description of the oil temperature adjusting valve
26. As shown in FIG. 2, the oil temperature adjusting valve 26 is provided at a
location where the oil supply path 20 is in communication with the oil path 38a and
the oil path 38b. Accordingly, the oil temperature adjusting valve 26 is provided so as
to be in communication with the oil recovery unit 21, an inflow portion 25b of the oil
cooler 25 into which oil to be cooled in the oil cooler 25 flows from the oil recovery unit
21, an outflow portion 25c of the oil cooler 25 from which oil cooled in the oil cooler 25
flows, and the compressor 12.
[0043] The oil temperature adjusting valve 26 shown in FIGS. 1 and 2 is provided by
way of a valve mechanism that adjusts the oil temperature by switching to either a
state of circulating oil to the oil cooler 25 or a state of restricting the circulation of oil, in
accordance with the temperature (oil temperature) of the oil in the oil tank 21b. This

oil temperature adjusting valve 26 is configured so as to include a body portion 39, a
valve plug 40, a valve plug driving portion 41, a communication position restriction
portion 42, and the like. Note that due to the operation of this oil temperature
adjusting valve 26, the oil temperature in the oil tank 21b is controlled, and the
oxidation of oil due to the oil temperature rising too high is prevented.
[0044] FIG. 3 is a diagram showing an enlarged view of the oil temperature adjusting
valve 26 shown in FIG. 2. As shown in FIGS. 2 and 3, the body portion 39 is
configured as a block-shaped structure that is provided with an internal space in
which the valve plug 40 is disposed, a first port 43a, a second port 43b, a third port 43c,
and a fourth port 43d that are in communication with the internal space. Note that
the body portion 39 may be configured by one member, or may be configured by an
integrated combination of multiple members as shown in FIG. 3.
[0045] The first port 43a is configured so as to be in communication with the oil
recovery unit 21 via the oil supply path 20. The second port 43b is configured so as to
be in communication with the inflow portion 25b of the oil cooler 25 via the oil path 38a.
The third port 43c is configured so as to be in communication with the outflow portion
25c of the oil cooler 25 via the oil path 38b. The fourth port 43d is configured so as to
be in communication with the compressor 12 via the oil supply supply path 20.
[0046] The valve plug 40 is provided by way of a structure in the shape of two
integrated tubes, for example. This valve plug 40 is provided with an inner tube
portion 40a disposed on the inner side, an outer tube portion 40b disposed outside of
the inner tube portion 40a, and multiple bridge portions 40c that span between the
inner tube portion 40a with the outer tube portion 40b so as to couple them. The
inner tube portion 40a is formed in the shape of a tube whose diameter decreases in a
stepwise manner from one end portion side to the other end portion side, for example.

The outer tube portion 40b is disposed concentrically with the inner tube portion 40a,
and is also disposed at a position that is eccentric with respect to the inner tube portion
40a toward one side in the axial direction of the inner tube portion 40a, for example.
[0047] Also, the bridge portions 40c project so as to radially extend outward in the
diameter direction from the outer circumference of the inner tube portion 40a, and are
provided so as to project from substantially equiangular positions in the
circumferential direction of the inner tube portion 40a, for example. Also, the bridge
portions 40c are each formed such that one end portion is integrally formed with the
outer circumference of the inner tube portion 40a, and the other end portion is
integrally formed with the inner circumference of the outer tube portion 40b. For this
reason, the inner tube portion 40a and the outer tube portion 40b are integrally
coupled via the bridge portions 40c, and spaces through which oil can flow are provided
between adjacent bridge portions 40c.
[0048] This valve plug 40 is disposed so as to be capable of sliding movement inside
the body portion 39. The valve plug 40 is configured so as to be switched between
positions, namely a circulation position at which oil is circulated to the oil cooler 25 and
a restriction position at which the circulation of oil to the oil cooler 25 is restricted.
FIG. 4 is a schematic diagram for describing operations of the oil temperature
adjusting valve 26, and shows the state in which the valve plug 40 is located at the
circulation position. On the other hand, FIG. 2 shows the state in which the valve
plug 40 is located at the restriction position.
[0049] The switching of the position of the valve plug 40 between the circulation
position and the restriction position is performed by the later-described valve plug
driving portion 41. As shown in FIG. 4, the valve plug 40 is configured such that
when in the state of being located at the circulation position, the first port 43a and the

second port 43b are put in communication, and the third port 43c and the fourth port
43d are put in communication, and thus oil is circulated to the oil cooler 25.
[0050] In FIG. 4, arrows C show the path in which oil circulates when the valve plug
40 is at the circulation position. When the valve plug 40 is at the circulation position,
oil that is discharged from the compressor 12 along with compressed air is recovered in
the oil tank 21b via the on-containing compressed air discharge path 21a. As
previously described, as compressed air pushes the oil level of the oil in the oil tank 21b
downward, oil flows from the oil tank 21b to the inflow portion 25b of the oil cooler 25
via the oil temperature adjusting valve 26. At this time, the oil flows into the oil
temperature adjusting valve 26 through the first port 43a, flows in the space between
the inner tube portion 40a and the outer tube portion 40b, and then flows out to the oil
path 38a through the second port 43b. The oil is then cooled in the oil cooler 25, flows
out through the outflow portion 25c, and is then suctioned into the compressor 12 via
the oil temperature adjusting valve 26. At this time, the oil flows into the oil
temperature adjusting valve 26 through the third port 43c, flows in the space outside
the outer tube portion 40b inside the body portion 39, and then flows out to the oil
supply path 20 through the fourth port 43d.
[0051] Note that at the circulation position shown in FIG. 4, one end side of an outer
circumferential side face 40d (see FIGS. 3 and 4) of the outer tube portion 40b of the
valve plug 40 is located at a position of being in close contact with a first inner
circumferential sealing face 39a provided as a wall face separating the first port 43a
from the third port 43c and the fourth port 43d in the body portion 39. The other end
side of the outer circumferential side face 40b is located at a position of being in close
contact with a second inner circumferential sealing face 39b provided as a wall face
separating the second port 43b from the third port 43c and the fourth port 43d in the

body portion 39. Accordingly, when the valve plug 40 is at the circulation position, the
oil path that puts the first port 43a and the second port 43b in communication and the
oil path that puts the third port 43c and the fourth port 43d in communication are
sealed off by the first and second inner circumferential sealing feces (39a, 39b) of the
body portion 39 and the outer circumferential side face 40d of the outer tube portion
40b, and thus are cut off from each other.
[0052] Also, as shown in FIG. 2, the valve plug 40 is configured such that when
located at the restriction position, the first port 43a is put in communication with the
fourth port 43d that is in communication with the third port 43c, and thus the
circulation of oil to the oil cooler 25 is restricted.
[0053] In FIG. 2, arrows A show the path in which oil circulates when the valve plug
40 is at the restriction position during operation of the compressor 12. When the
valve plug 40 is at the restriction position, oil that is discharged from the compressor
12 along with compressed air is recovered in the oil tank 21b via the ou-amtaining
compressed air discharge path 21a. Then, as compressed air pushes the oil level of
the oil in the oil tank 21b downward, oil flows from the oil tank 21b via the oil
temperature adjusting valve 26, and is suctioned into the compressor 12. At this time,
the first inner circumferential sealing face 39a and the outer circumferential side face
40b are separated from each other, the oil flows into the oil temperature adjusting
valve 26 through the first port 43a, flows in the space between the first inner
circumferential sealing face 39a and the outer tube portion 40b, and then flows out to
the oil supply path 20 through the fourth port 43d.
[0054] Also, at the restriction position shown in FIG. 2, the outer circumferential side
face 40d of the outer tube portion 40b is located at a position of being separated from
the first inner circumferential sealing face 39a, and being in close contact with the

second inner circumferential sealing face 39b. An end face 40e (see FIG. 3) of an end
portion of the outer tube portion 40b on the side opposite to the first port 43a is located
at a position of being in close contact with an end face 39c of an end of a portion of the
body portion 39 that is tube-shaped and projects out from a position that corresponds
to the second port 43b.
[0055] Note that at the above-described restriction position, the second port 43b is in
communication with the first and fourth ports (43a, 43d) via the laterdescribed
communication position restriction portion 42, and the third port 43c is also in
communication with the first and fourth ports (43a, 43d). For this reason, the oil
pressure is maintained in a balanced state in the oil path 38a and the oil path 38b
between the oil temperature adjusting valve 26 and the oil cooler 25, as shown by
double-ended arrows B in FIG. 2.
[0056] The valve plug driving portion 41 is provided by way of a mechanism that
independently operates in accordance with the temperature (oil temperature) of the oil
31 in the oil tank 21b, and drives the valve plug 40 such that the position of the valve
plug 40 switches between the circulation position and the restriction position. As
illustrated in FIGS. 2 to 4, the valve plug driving portion 41 includes a spring 44 and a
shaft portion 45 with a built-in bimetal mechanism that changes volume according to
the temperature, and thus is configured as an independent driving mechanism that
operates according to the temperature.
[0057] The spring 44 is provided by way of a coil spring for example, is disposed in
the internal space of the body portion 39, and is disposed between the outer tube
portion 40b and the inner tube portion 40a of the valve plug 40. Also, one end side of
the spring 44 comes into contact with the inner wall of the body portion 39 in a
peripheral portion of the first port 43a, and the other end side comes into contact with

the bridge portions 40c. Accordingly, the spring 44 biases the valve plug 40 toward
the side opposite to the first port 43a in the body portion 39.
[0058] One end portion of the shaft portion 45 with a built-in bimetal mechanism is
attached to the body portion 39, and the other end portion is attached to the valve plug
40. The one end portion of the shaft portion 45 is attached to the body portion 39 due
to being fitted into an attachment hole 39d formed in the inner wall on the side
opposite to the first port 43a. The other end side of the shaft portion 45 is attached to
the inner tube portion 40a on the inner side of the inner tube portion 40a. Also, the
portion of the shaft portion 45 that is disposed inside the inner tube portion 40a is
maintained in the state of being immersed in the oil 31 that has flowed from the oil
tank 21b. Accordingly, the shaft portion 45 is configured so as to operate according to
the oil temperature in the oil tank 21b.
[0059] Also, the length of the shaft portion 45 decreases if the oil temperature in the
oil tank 21b is lower than or equal to a predetermined temperature. For this reason,
the valve plug 40 is biased toward the side opposite to the first port 43a in the body
portion 39 due to the spring force of the spring 44, and the state of being switched to
the restriction position shown in FIG. 2 is maintained. Accordingly, if the oil
temperature in the oil tank 21b is a low temperature that is lower than or equal to the
predetermined temperature, the circulation of oil to the oil cooler 25 is restricted, and
oil is not cooled by the oil cooler 25.
[0060] On the other hand, the length of the shaft portion 45 increases if the oil
temperature in the oil tank 21b exceeds the predetermined temperature. For this
reason, the valve plug 40 is biased toward the first port 43a side in the body portion 39
by the shaft portion 45 that extends against the spring force of the spring 44, and the
valve plug 40 is switched to the circulation position shown in FIG. 4. Accordingly, if

the oil temperature in the oil tank 21b is a high temperature that exceeds the
predetermined temperature, oil is circulated to the oil cooler 25, and oil is cooled by the
oil cooler 25.
[0061] The restriction position communication portion 42 shown in FIGS. 2 to 4 is
provided by way of a mechanism that puts second port 43b in communication with the
first port 43a when the valve plug 40 is at the restriction position. In the present
embodiment, the restriction position communication portion 42 is configured as a
through-hole (also referred to hereinafter as the "through-hole 42") formed in a
penetrating manner so as to put the inner side and the outer side of the outer tube
portion 40b of the valve plug 40 in communication.
[0062] As shown in FIGS. 2 and 3, one opening of the through-hole 42 is disposed so
as to oppose the second port 43b when the valve plug 40 is at the restriction position.
For this reason, when the valve plug 40 is at the restriction position, the state in which
the second port 43b is in communication with the first port 43a via the through-hole 42
is maintained. On the other hand, when the valve plug 40 is at the circulation
position as shown in FIG. 4, the one opening of the through-hole 42 is disposed so as to
be blocked by a wall portion 46 of the body portion 39 that is provided between the
second port 43b and the third port 43c. In other words, the one opening of the
through-hole 42 is in the state of being blocked by the second inner circumferential
sealing face 39b of the wall portion 46.
[0063] Next, operations of the above-described air compressing device 1 will be
described. In the state in which the air compressing device 1 is operating so as to
generate compressed air, firstly, air (outside air) is suctioned through the air suction
unit 18 due to negative pressure produced by the operation of the compressor 12. The
suctioned air then passes through the suction valve 29, which is in the open state due

to the pressure of the suctioned air, and flows into the compressor 12. At this time, oil
has been supplied from the oil supply path 20 to the compressor 12 as described above,
and the suctioned air is compressed along with oil in the compressor 12.
[0064] The compressed air that was compressed along with oil passes through the
ofl-containing compressed air discharge path 21a, further passes through the
separator 30, and is discharged into the oil tank 21b. Also, oil that is separated from
the compressed air by the separator 30 is recovered in the oil tank 21b. This
recovered oil is supplied to the compressor 12 via the oil supply path 20.
[0065] The compressed air that was discharged into the oil tank 21b passes through
the oil separation element 22, and oil is further separated from the compressed air.
The compressed air that passes through the oil separation element 22 is then guided to
the after cooler 17 and cooled in the after cooler 17. The compressed air that was
cooled by the after cooler 17 is then subjected to water component and oil component
separation in the water-oil separator 23, subjected to dehumidification in the
dehumidifier 24, and then delivered from the compressed air delivery unit 19 to the air
tank.
[0066] In the state in which operation for generating compressed air is being
performed as described above, if the oil temperature in the oil tank 21b is lower than
or equal to a predetermined temperature, the state in which the valve plug 40 of the oil
temperature adjusting valve 26 is located at the restriction position as shown in FIG. 2
is maintained. As described above, in this state, the circulation of oil to the oil cooler
25 is restricted, oil is not cooled by the oil cooler 25, and oil is circulated between the oil
recovery unit 21 and the compressor 12.
[0067] On the other hand, if the oil temperature in the oil tank 21b rises to the state
of being a high temperature that exceeds the predetermined temperature, the valve

plug 40 is driven by the valve plug driving portion 41 as described above, and the valve
plug 40 is switched to the circulation position as shown in FIG. 4. As described above,
in this state, oil is circulated in a path that extends from the oil recovery unit 21 to the
compressor 12 via the oil cooler 25, and the oil is cooled by the oil cooler 25.
[0068] When the above-described operation for generating compressed air ends in the
air compressing device 1, the operation of the compressor 12 is stopped. If the oil
temperature in the oil tank 21b is a low temperature that is lower than or equal to the
predetermined temperature at this stop timing, the valve plug 40 of the oil
temperature adjusting valve 26 is located at the restriction position. Since the
operation of the compressor 12 is stopped and the oil temperature remains at a low
temperature, the state in which the valve plug 40 is located at the restriction position
is maintained. On the other hand, if the oil temperature in the oil tank 21b is a high
temperature that exceeds the predetermined temperature at the stop timing of the
compressor 12, the valve plug 40 is located at the circulation position. However, since
the operation of the compressor 12 is stopped and the oil temperature decreases, the
position of the valve plug 40 will be switched from the circulation position to the
restriction position due to the operation of the valve plug driving portion 41, and the
state in which the valve plug 40 is located at the restriction position is maintained.
Accordingly, when the operation of the air compressing device 1 stops, after at least a
certain period of time has elapsed and the oil temperature has decreased, the state in
which the position of the valve plug 40 is switched to the restriction position will be
achieved.
[0069] FIG. 5 is a schematic diagram for describing operations of the oil temperature
adjusting valve 26, and shows the state in which the valve plug 40 is located at the
restriction position after the operation of the compressor 12 stops as described above.

Also, in FIG. 5, arrows D show the flow path of oil after the operation of the
compressor 12 has stopped. In the state in which the operation of the compressor 12
has stopped and the valve plug 40 is located at the restriction position, the opening of
the through-hole 42 opposes the second port 43b, and the state in which the second
port 43b and the first port 43a are in communication is maintained. For this reason,
gravity causes oil to flow out from the oil cooler 25, which is disposed higher than the
oil tank 21b. The oil then flows out through the outflow portion 25c of the oil cooler 25,
and also flows out through the inflow portion 25b of the oil cooler 25 in the opposite
mariner from when oil cooling is performed.
[0070] Due to gravity, the oil that flows out through the inflow portion 25b of the oil
cooler 25 passes through the oil path 38a and flows through the second port 43b to the
inner side of the outer tube portion 40b via the through-hole 42, then flows out through
the first port 43a and is recovered in the oil tank 21b due to flowing in the opposite
manner from when the oil supply path 20 is operating. Also, due to gravity, the oil
that flows out through the outflow portion 25c of the oil cooler 25 passes through the
oil path 38b and flows through the third port 43c to the inner side of the body portion
39, then flows out through the first port 43a and is recovered in the oil tank 21b due to
flowing in the opposite manner from when the oil supply path 20 is operating.
[0071] As described above, according to the present embodiment, in the air
compressing device for a railway vehicle 1, which is configured as a device that
generates compressed air by compressing air accompanied by oil and then separating
the oil from the compressed air, the oil temperature adjusting valve 26 causes a switch
to either a state of circulating oil to the oil cooler 25 or a state of restricting oil
circulation, in accordance with the oil temperature in the oil tank 21b. For this
reason, when the oil temperature is a high temperature, oil cooling is performed, and

the oil temperature is adjusted. With the oil temperature adjusting valve 26, the
position of the valve plug 40 is switched between the circulation position and the
restriction position by the independent valve plug driving portion 41 that
independently differentiates according to the oil temperature. Accordingly, during
operation of the air compressing device 1, in the circulation position state, the oil
recovery unit 21 side and the inflow portion 25b side of the oil cooler 25 are connected,
the outflow portion 25c side of the oil cooler 25 and the compressor 12 side are
connected, and oil cooling is performed. In the restriction position state, the oil
recovery unit 21 side and the compressor 12 side are connected, and the circulation of
oil to the oil cooler 25 is restricted.
[0072] On the other hand, after the operation of the air compressing device 1 has
stopped, even if the position of the valve plug 40 is the circulation position at the stop
timing, the position of the valve plug 40 will be switched to the restriction position due
to the operation of the independent valve plug driving portion 41 that accompanies a
decrease in the oil temperature. At this time, the state in which the second port 43b
and the first port 43a are in communication is maintained since the oil temperature
adjusting valve 26 is provided with the restriction position communication portion 42.
For this reason, after the operation of the air compressing device 1 stops, after at least
a certain period of time has elapsed and the oil temperature has decreased, the state in
which the first port 43a is in communication with the second port 43b and the third
port 43c is maintained. Accordingly, the state in which the inflow portion 25b side
and the outflow portion 25c side of the oil cooler 25 are in communication with the oil
recovery unit 21 side is maintained, and the operation of the compressor 12 is also
stopped, and therefore the accumulation of oil in the oil cooler 25 and in the path that
puts the oil cooler 25 and the oil tank 21b in communication is suppressed, oil is

recovered in the oil tank 21b, and variation in the amount of recovered oil is
suppressed. This suppresses the situation in which, even when the total amount of
oil circulated in the device is the same, the oil level position varies depending on the
operation state of the oil temperature adjusting valve 26 when operation is stopped,
such that the oil level position converges at a stable and substantially identical
position when the operator checks the oil level in the oil tank 21b using the oil level
gauge 27. For this reason, the operator can easily and precisely determine whether or
not the oil needs to be replenished.
[0073] According to the present embodiment, it is possible to provide an air
compressing device for a railway vehicle 1 that enables easily and precisely
determining whether or not oil needs to be replenished.
[00741 Also, according to the air compressing device 1, the restriction position
communication portion 42 is provided by way of a through-hole formed in the valve
plug 40. This enables easily constructing the restriction position communication
portion 42 with a simple structure. Note that the one opening of the restriction
position communication portion 42 provided by way of a through-hole is in
communication with the second port 43b only when at the restriction position, and is
blocked by the wall portion 46 between the second port 43b and the third port 43c
when at the circulation position. When at the circulation position, this prevents the
through-hole serving as the restriction position communication portion 42 from
putting the first port 43a in communication with the third port 43c and the fourth port
43d, and prevents the circulation of oil to the oil cooler 25 from being inhibited due to
the oil recovery unit 21 side being in communication with the outflow portion 25c side
of the oil cooler 25 and the compressor 12 side.
[0075] Although an embodiment of the present invention is described above, the

present invention is not limited to the above-described embodiment, and can be carried
out with various modifications within the scope of the claims. Although the above
embodiment describes the example of a configuration including an after cooler, an oil
separation element, a water-oil separator, a dehumidifier, and the like, the inclusion of
these configurations is not necessarily required. Also, although the above
embodiment describes the example of a mode in which devices such as the compressor
and the oil recovery unit are stored in the storage case, this mode is not required.
Also, although the above embodiment describes the example of a mode in which the
restriction position communication portion is a mechanism that is provided integrally
with the valve plug, this mode is not necessarily required. For example, the
restriction position communication portion may be a mechanism that includes a
solenoid valve or the like and is provided so as to be able to operate independently from
the valve plug. Also, although the above embodiment describes the example where
the mode of the valve plug driving portion is the mode of being configured so as to
include a shaft portion with a built-in bimetal mechanism, this is not required. The
valve plug driving portion may be configured as a mechanism that independently
operates according to the oil temperature. For example, it may be configured as a
mechanism that uses wax that changes volume according to the temperature.
Industrial Applicability
[0076] The present invention is widely applicable to an air compressing device for a
railway vehicle, which is installed in a railway vehicle and generates compressed air
that is used in the railway vehicle.
Descriptions of Reference Numerals

CLAIMS
1. An air compressing device for a railway vehicle that is disposed in a railway
vehicle and generates compressed air that is used in the railway vehicle, the air
compressing device comprising:
a compressor that compresses air suctioned from the outside;
an oil supply path that supplies oil to the compressor;
an oil recovery unit that has an oil tank, separates oil from compressed air
guided thereto that was compressed along with oil in the compressor, recovers the
separated oil in the oil tank, and is in communication with the oil supply path;
an oil cooler that cools the oil recovered in the oil tank; and
an oil temperature adjusting valve that adjusts an oil temperature, being the
temperature of the oil in the oil tank, by switching to one of a state of circulating oil to
the oil cooler and a state of restricting oil circulation, in accordance with the oil
temperature,
wherein the oil temperature adjusting valve has:
a body portion provided with a first port for communication with the oil
recovery unit, a second port for communication with an inflow portion of the oil cooler
into which oil to be cooled in the oil cooler flows from the oil recovery unit, a third port
for communication with an outflow portion of the oil cooler from which oil cooled in the
oil cooler flows, and a fourth port for communication with the compressor;
a valve plug that is disposed so as to be capable of sliding movement inside the
body portion, a position of the valve plug being switched between a circulation position
at which oil is circulated to the oil cooler by putting the first port and the second port in
communication and putting the third port and the fourth port in communication, and
a restriction position at which the circulation of oil to the oil cooler is restricted by

putting the first port in communication with the fourth port that is in communication
with the third port;
a valve plug driving portion that independently operates according to the oil
temperature and drives the valve plug such that the position of the valve plug is
switched between the circulation position and the restriction position; and
a restriction position communication portion that puts the second port in
communication with the first port when the valve plug is at the restriction position.
2. The air compressing device for a railway vehicle according to claim 1,
wherein the restriction position communication portion is provided by way of a
through-hole formed in the valve plug, and
when the valve plug is at the restriction position, one opening of the
through-hole opposes the second port, and when the valve plug is at the circulation
position, the one opening of the through-hole is blocked by a wall portion in the body
portion, the wall portion being provided between the second port and one of the third
port and the fourth port.