[0001] The present disclosure described herein, in general, relates to a
synchronizer for power transmission and a method to operate the synchronizer
5 that reduces the double-bump phenomenon.
BACKGROUND
[0002] In a general or known state of the art, a synchronizer for manual
transmission of power comprises a hub, a sleeve, a pair of synchronizer rings, a
pair of dog gears attached with a pair of transmission gears and synchro keys that
10 are connected with each other and other accessories in a known way. In a broad
description, the sleeve that is slidable in an axial direction engages with one of the
synchronizer rings at either side of the sleeve or hub on a rotating shaft and then
engages with the dog gear of the transmission gear. Hence, power transmission
takes place by two-stage engagement of the sleeve. In both the stages of
15 engagement, a bump or a jerk is experienced by an occupant. The bump (also
known as double bump) caused by the second engagement, i.e., engagement of the
sleeve with the dog gear is more unpleasant to the occupant and hence many
efforts have been made in the past to reduce this bump. The drawbacks with the
known efforts are an improper engagement of the sleeve with the dog gear,
20 increase in the number of parts and hence cost, the complexity of assembly, and
so forth.
[0003] In view of the above, there is a need to provide an alternate solution or
way of reducing the double bump phenomenon that doesn’t provide the abovementioned drawbacks.
25 OBJECTS OF THE DISCLOSURE
[0004] Some of the objects of the present disclosure, which at least one
embodiment herein satisfy, are listed hereinbelow.
3
[0005] It is a general or primary object of the present disclosure to provide a
synchronizer for power transmission and method to operate such synchronizer that
can reduce the double bump phenomenon without increasing the number of parts,
cost, and complexity of the assembly and provides proper engagement between
5 the sleeve and the dog gear.
[0006] This and other objects will become more apparent when reference is
made to the following description and accompanying drawings.
SUMMARY
[0007] This summary is provided to introduce concepts related to a
10 synchronizer for power transmission and a method to operate said synchronizer.
The concepts are further described below in the detailed description. This
summary is not intended to identify key features or essential features of the
claimed subject matter, nor is it intended to be used to limit the scope of the
claimed subject matter.
15 [0008] The subject matter disclosed herein relates to a synchronizer for power
transmission. The synchronizer comprises a sleeve fitted over an outer peripheral
surface of a hub that is fixed to a rotating shaft, the sleeve has two annular flanges
having different heights and formed around its outer peripheral surface, wherein
an annular spline having a predefined width is formed as an extension from the
20 two flanges at each side periphery of the sleeve. Therefore, with the provision of
the annular spline having the tapered end surface the double bump phenomenon is
reduced.
[0009] In an aspect, the annular spline has a tapered end surface that forms a
press-contact with a tapered end surface of a dog gear annular flange on outer
25 periphery of which a plurality of dog teeth are formed.
4
[0010] In an aspect, the width of the annular spline corresponds to a width of
a portion of the dog gear annular flange which is not covered by the plurality of
dog teeth.
[0011] The subject matter disclosed herein also relates to a method of
5 operating a synchronizer for power transmission. The method comprises presscontacting a tapered end surface of an annular spline of the sleeve with a tapered
end surface of a dog gear annular flange on outer periphery of which a plurality of
dog teeth are formed; and sliding and engaging (504) of sleeve spines of the
sleeve with the plurality of dog teeth of a dog gear.
10 [0012] To further understand the characteristics and technical contents of the
present subject matter, a description relating thereto will be made with reference
to the accompanying drawings. However, the drawings are illustrative only but
not used to limit the scope of the present subject matter.
[0013] Various objects, features, aspects, and advantages of the inventive
15 subject matter will become more apparent from the following detailed description
of preferred embodiments, along with the accompanying drawing figures in which
like numerals represent like components.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] It is to be noted, however, that the appended drawings illustrate only
20 typical embodiments of the present subject matter and are therefore not to be
considered for limiting of its scope, for the invention may admit to other equally
effective embodiments. The detailed description is described with reference to the
accompanying figures. The illustrated embodiments of the subject matter will be
best understood by reference to the drawings, wherein like parts are designated by
25 like numerals throughout. The following description is intended only by way of
example, and simply illustrates certain selected embodiments of devices, systems,
and methods that are consistent with the subject matter as claimed herein,
wherein:
5
[0015] FIG. 1 illustrates an exploded view of the components of a typical
synchronizer;
[0016] FIG. 2 illustrates a cross-section view of the assembled components of
the typical synchronizer on a rotating shaft;
5 [0017] FIG. 3A and 3B illustrate a sleeve of a synchronizer in accordance
with the present disclosure and its differentiation from a known sleeve;
[0018] FIG. 4A and 4B illustrate a cross-section view of the engagement of
the sleeve disclosed in FIG. 3A in accordance with the present disclosure; and
[0019] FIG. 5 illustrates a method of operation of the synchronizer with the
10 sleeve disclosed in FIG. 3A in accordance with the present disclosure.
[0020] The figures depict embodiments of the present subject matter for the
purposes of illustration only. A person skilled in the art will easily recognize from
the following description that alternative embodiments of the structures and
methods illustrated herein may be employed without departing from the principles
15 of the disclosure described herein.
DETAILED DESCRIPTION
[0021] The detailed description of various exemplary embodiments of the
disclosure is described herein with reference to the accompanying drawings. It
should be noted that the embodiments are described herein in such details as to
20 communicate the disclosure. However, the amount of details provided herein is
not intended to limit the anticipated variations of embodiments; on the contrary,
the intention is to cover all modifications, equivalents, and alternatives falling
within the spirit and scope of the present disclosure as defined by the appended
claims.
25 [0022] It is also to be understood that various arrangements may be devised
that, although not explicitly described or shown herein, embody the principles of
6
the present disclosure. Moreover, all statements herein reciting principles, aspects,
and embodiments of the present disclosure, as well as specific examples, are
intended to encompass equivalents thereof.
[0023] The terminology used herein is to describe particular embodiments
5 only and is not intended to be limiting of example embodiments. As used herein,
the singular forms “a”, “an” and “the” are intended to include the plural forms as
well, unless the context indicates otherwise. It will be further understood that the
terms “comprises”, “comprising”, “includes” and/or “including,” when used
herein, specify the presence of stated features, integers, steps, operations,
10 elements and/or components, but do not preclude the presence or addition of one
or more other features, integers, steps, operations, elements, components and/or
groups thereof.
[0024] It should also be noted that in some alternative implementations, the
functions/acts noted may occur out of the order noted in the figures. For example,
15 two figures shown in succession may be executed concurrently or may sometimes
be executed in the reverse order, depending upon the functionality/acts involved.
[0025] Unless otherwise defined, all terms (including technical and scientific
terms) used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which example embodiments belong. It will be further
20 understood that terms, e.g., those defined in commonly used dictionaries, should
be interpreted as having a meaning that is consistent with their meaning in the
context of the relevant art and will not be interpreted in an idealized or overly
formal sense unless expressly so defined herein.
[0026] In the following detailed description of the embodiments of the
25 disclosure, reference is made to the accompanying drawings that form a part
hereof, and in which are shown by way of illustration specific embodiments in
which the disclosure may be practiced. These embodiments are described in
sufficient detail to enable those skilled in the art to practice the disclosure, and it
is to be understood that other embodiments may be utilized and that changes may
7
be made without departing from the scope of the present disclosure. The
following description is, therefore, not to be taken in a limiting sense.
[0027] Hereinafter, a description of an embodiment with several components
in communication with each other does not imply that all such components are
5 required. On the contrary, a variety of optional components are described to
illustrate the wide variety of possible embodiments of the present disclosure.
[0028] Reference is made to FIG. 1 that shows an exploded view of major
components of a typical or known synchronizer 100. The synchronizer 100 mainly
comprises a rotating shaft (not shown in FIG. 1), a hub 102, a sleeve 104, a pair of
10 synchronizer rings 106, a pair of dog gears 108, a pair of transmission gears, and
keys 110.
[0029] The hub 102 is an annular member that is fixed to the rotating shaft by
inserting the hun 102 in its inner peripheral surface 102a and that rotates with the
rotating shaft. In an aspect, the hub 102 is fixed to the rotating shaft by spline
15 fitting where the rotating shaft is formed with splines. Once fixed with the
rotatable shaft, the hub 102 is non-slidable in an axial direction of the rotating
shaft. The hub 102 includes a plurality of hub splines S1 at its outer peripheral
surface 102b.
[0030] The sleeve 104 is also an annular member that is fitted over the outer
20 peripheral surface 102b of the hub 102. The sleeve 104 inlcudes a plurality of
sleeve splines S2 formed in its inner peripheral surface 104a that engages with the
hub splines S1. The sleeve 104 and the hub 102 therefore, rotate at the same
speed. The sleeve 104 has two annular flanges 104c, 104d (FIG. 2) having
different heights, and formed around its outer peripheral surface 104b. In an
25 aspect, the annular flange 104c has less height than the annular flange 104d. The
sleeve 104 in operation is slidable in a left/right direction or an axial direction of
the rotating shaft to engage with one of the synchronizer rings 106 and
subsequently with the dog gear 108 based on a requirement of a specific speed
limit.
8
[0031] Each of the synchronizer rings 106 is provided between the dog gear
108 and the sleeve 104 or hub 102, and are identical to one another. The
synchronizer ring 106 has a conical surface 106a that is fitted with a conical
surface 108a of the dog gear 108. Each of the synchronizer rings 106 has a
5 plurality of ring teeth T1 formed on its outer periphery and a plurality of ring
splines S3 at its side periphery that engages with the plurality of sleeve splines S2
and a plurality of locking recesses (not shown) of the hub 102 during the
operation, respectively. The purpose of the synchronizer rings 106 is to produce
friction torque needed to synchronize the sleeve 104 with the dog gear 108.
10 [0032] The dog gears 108 matches the speed of the transmission gear with the
hub 102. The dog gears 108 are fixed to a side surface of the transmission gear by
either press-fitting or laser welding. Each of the dog gears 108 comprises a
plurality of dog teeth T2 formed at an annular flange 108b on its outer periphery
to engage with the plurality of sleeve splines S2 during engagement for power
15 transmission. The number of dog teeth T2 varies in each of the dog gears 108.
Each of the dog teeth T2 may have a tapered end surface (not shown). The
transmission gears are connected to the rotating shaft by a needle bearing for
relative rotation between both of them and secured against axial movement
relative to the rotating shaft.
20 [0033] The synchro keys 110 are positioned between grooves 102c in the hub
102 and the inner groove (not shown) the sleeve 104. The synchro keys 110 are
both rotatable and slidable, and are used for pre-synchronization, i.e., to generate
load on the synchronizer rings 106 to perform synchronization or engagement.
[0034] FIG. 2 shows a cross-section of an assembled state of the various
25 components of the synchronizer 100 on the rotating shaft 200, before engagement
of the sleeve 104 with the dog gear 108.
[0035] In operation, due to generation synchronous load, the sleeve 104 slides
axially either left or right towards one of the synchronizer rings 106. Meanwhile,
the synchro keys 110 also generates friction load on the synchronizer ring 106
9
moving it axially. The plurality of sleeve splines S2 first engages with the
plurality of ring teeth T1 first and subsequnelty engages with the plurality of dog
teeth T2 subsequently. Thus, the sleeve 104 in operation is slidable in a left/right
direction or an axial direction of the rotating shaft to engage with one of the
5 synchronizer rings 106 and subsequently with the dog gear 108 based on a
requirement of a specific speed limit. Post engagement of the plurality of sleeve
splines S2 with the plurality of ring teeth T2, the sleeve 104 gets tilted with in
axial direction of the rotating shaft and causes a jerk also known as double bump
phenomenon that is unpleasant to an occupant.
10 [0036] To reduce the double bump phenomenon, the sleeve 104' in
accordance with the present disclosure, unlike the sleeve 104 of the known
synchronizer 100, includes an annular spline 300 as shown in FIGS. 3A and 3B.
having a predefind width WAS formed as an extension from the two annular
flanges 104c, 104d at each side periphery of the sleeve 104'. In an aspect, but not
15 limited to, the width WAS of the annular spline 300 corresponds to a width of a
portion, of the dog gear’s annular flange 108b, which is not covered by the
plurality of dog teeth T2. Generally, the dog teeth T2 are formed on the dog gear’s
annular flange 108b at a distance/width away from an edge facing the sleeve 104ʹ
or the synchronizer ring 106.
20 [0037] FIG. 3B shows a cross-section of the sleeve 104' in accordance with
the present disclosure having the annular spline 300 at each of its side periphery
having a tapered end surface 300a in addition to the structure described for the
sleeve 104 as shown in FIG. 1.
[0038] FIGS. 4A and 4B show a cross-section of engagement of the sleeve
25 104' in accordance with the present disclosure. It can be seen that the tapered end
surface 300a of the annular spline 300 forms a press-contact with a tapered end
surface 400 of the dog gear’s annular flange 108b by virtue of the tilted position
of the sleeve 104', post engagement with the plurality of ring teeth T1 of the
synchronizer ring 106, and then slides over the dog gear 108 for engagement. This
10
press-contact of the sleeve 104', before actual engagement, with the dog gear 108
facilitates smooth engagement between the sleeve 104' and the dog gear, thereby
reduces the double bump phenomenon. The engagement of the sleeve 104' shown
with the transmission gear on the left-hand side as shown in FIG. 4 is only for
5 demonstration. The engagement of the sleeve 104' takes place similarly with the
transmission gear on the right-hand side.
[0039] FIG. 5 shows a flow chart of a method 500 of operating the
synchronizer 100 in accordance with the present disclosure. The method 500
comprises a step 502 of press-contacting the tapered end surface 300a of the
10 annular spline 300 of the sleeve 104' with the tapered end surface 400 of the dog
gear annular flange 108b. As mentioned above, the plurality of dog teeth T2
formed on the outer periphery of the dog gear annular flange 108b.
[0040] The method step 502 is followed by subsequent step 504 of sliding and
engaging of the sleeve spines S2 of the sleeve 104' with the plurality of dog teeth
15 T2 of the dog gear 108. This subsequent engagement is resulted by the formation
of the press-contact between a tapered end surface 300a of the annular spline 300
and the tapered end surface 400 of the dog gear annular flange 108b by virtue of a
tilted position of the sleeve 104', post engagement with the plurality of ring teeth
T1 of the synchronizer ring 106. This press-contact of the sleeve 104', before
20 actual engagement, with the dog gear 108 facilitates smooth engagement between
the sleeve 104' and the dog gear, thereby reduces the double bump phenomenon.
Further, as per the present disclosure, since the number of parts has not increased
therefore, the cost and complexity of the assembly is also controlled.
TECHNICAL ADVANTAGES
25 [0041] The present disclosure provides a synchronizer for power transmission
and method to operate such a synchronizer that can reduce the double bump
phenomenon without increasing the number of parts, cost, and complexity of the
assembly and provides proper engagement between the sleeve and the dog gear.
11
[0042] While the foregoing describes various embodiments of the present
disclosure, other and further embodiments of the present disclosure may be
devised without departing from the basic scope thereof. The scope of the
invention is determined by the claims that follow. The present disclosure is not
5 limited to the described embodiments, versions or examples, which are included
to enable a person having ordinary skill in the art to make and use the present
disclosure when combined with information and knowledge available to the
person having ordinary skill in the art.

We claim:

1. A synchronizer (100) for power transmission, the synchronizer (100)
comprising:
a sleeve (104') fitted over an outer peripheral surface (102b) of a hub (102)
5 that is fixed to a rotating shaft (200), the sleeve (104') has two annular flanges
(104c, 104d) with different heights and formed around its outer peripheral surface
(104b),
wherein an annular spline (300) having a predefined width (WAS) is formed
as an extension from each of the two annular flanges (104c, 104d) at each side
10 periphery of the sleeve (104').
2. The synchronizer (100) as claimed in claim 1, wherein the annular spline
(300) has a tapered end surface (300a) that forms a press-contact with a tapered
end surface (400) of a dog gear annular flange (108b) on outer periphery of which
a plurality of dog teeth (T2) are formed.
15
3. The synchronizer (100) as claimed in claim 1, wherein the width (WAS)
of the annular spline (300) corresponds to a width of a portion of the dog gear
annular flange (108b) which is not covered by the plurality of dog teeth (T2).
20 4. A method of operating a synchronizer (100) for power transmission, the
method comprising:
press-contacting (502) a tapered end surface of an annular spline
(300) of the sleeve (104') with a tapered end surface (400) of a dog gear annular
flange (108b) on outer periphery of which a plurality of dog teeth (T2) are
25 formed; and
sliding and engaging (504) sleeve spines (S2) of the sleeve (104')
with the plurality of dog teeth (T2) of a dog gear (108).