TECHNICAL FIELD
The present disclosure generally relates to the field of gear position sensors.
Particularly, but not exclusively, the present disclosure relates to an improved magnet
holder assembly for a gear position sensor unit comprising a magnet holder having an
anti-rotation clip for the magnet holder of the gear position sensor.
BACKGROUND
The information in this section merely provide background information related to the
present disclosure and may not constitute prior art(s).
Magnet holder units are commonly used in gear position sensors of vehicles. The gear
position sensor comprises of a magnet assembled inside the magnet holder, and a Hall
IC mounted on a PCB assembly which is located inside a housing. The function of the
magnet holder is to hold the magnet firmly so that the gear position sensor provides
the correct output signal specification characteristic to ECU and it will show correct
gear position at the display unit of a vehicle.
In existing techniques, the magnet is assembled in the magnet holder by pressing the
magnet in a pocket provided in the magnet holder. As illustrated in Figure 1, the
magnet holder is engaged with a rotor by a screw and a lock plate locks the magnet
holder in the housing to restrict movement along Z-direction. The gear position
sensor consists of a magnet assembled inside the magnet holder and a Hall IC
mounted on a PCB which is located inside housing. Tight fitment of the magnet
holder in rotor is achieved by means of crushing ribs on the magnet holder. However,
during operation i.e. in dynamic condition, due to conditions of thermal expansion
under high temperature in oil medium and vibration level at 51 g, the magnet holder
tends to expand. The expansion of the magnet holder causes the thread engagement of
the screw with the magnet holder to get loose. Consequently, the screw becomes
loose and the magnet holder rubs against the rotor in the Z-direction. Due to the
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rubbing action, the crushing ribs wear out from the magnet holder creating a gap
between the magnet holder and the rotor. As a result, during operation, the magnet
holder rotates with respect to the rotor. This movement and rotation of magnet holder
causes the gear position sensor to fail its primary function to show correct output
signal specification characteristic and adversely affects the performance of the
vehicle.
In the light of the foregoing discussion, there is need to develop a lock mechanism for
locking the magnet holder (plastic part) in rotor (metal part) in dynamic condition to
overcome the limitations stated above.
SUMMARY OF THE INVENTION
One or more shortcomings of the prior art are overcome by an improved magnet
holder assembly for a gear position sensor unit as claimed and additional advantages
are provided through the provision of assembly as claimed in the present disclosure.
According to an aspect of the present disclosure, an improved magnet holder
assembly for a gear position sensor unit is provided. The said improved magnet
holder assembly comprises housing, a rotor coupled with a gearbox drum and a
magnet holder mounted in the housing. The magnet holder comprises a pocket for
holding a magnet, and an elongated shaft being received concentrically in a slot of the
rotor. At least one rib is formed externally on the elongated shaft to engage with a
corresponding recess of the slot of the rotor to restrict its relative movement. A clip is
mounted resiliently between the elongated shaft and the slot of the rotor. A PCB
assembly is configured in the housing.
4
In an embodiment of the present disclosure, the elongated shaft of the magnet holder
has at least one flat primary side wall, two L-shaped secondary side walls and a semicircular
peripheral tapered wall.
In another embodiment of the present disclosure, the slot of the rotor is in conformity
with the shape and size of the elongated shaft of the magnet holder unit.
In yet another embodiment of the present disclosure, the elongated shaft comprises a
threaded groove for securing the rotor with the magnet holder unit by means of a
screw.
In another embodiment of the present disclosure, the clip has a ‘L-shape’ having a
long arm and a short arm.
In a further embodiment of the present disclosure, the long arm of the clip has a
curved portion; the curved portion being disposed between the primary side wall of
the magnet holder unit and the slot of the rotor to maintain a resilient force on the
elongated shaft and restrict rotation of the magnet holder inside the rotor.
In a still further embodiment of the present disclosure, the short arm of the clip has a
hole for receiving the screw; and a circular flared projection extending inwardly
towards the threaded groove of elongated shaft of the magnet holder unit.
In another embodiment of the present disclosure, the PCB assembly comprises a Hall
IC disposed below the magnet, in the housing; and a PCB is connected with the Hall
IC.
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BRIEF DESCRIPTION OF DRAWINGS
Further aspects and advantages of the present disclosure will be readily understood
from the following detailed description with reference to the accompanying drawings.
Reference numerals have been used to refer to identical or similar functionally similar
elements. The figures together with a detailed description below, are incorporated in
and form part of the specification, and serve to further illustrate the embodiments and
explain various principles and advantages, in accordance with the present disclosure
wherein:
Figure 1 illustrates an existing gear position sensor unit.
Figure 2 depicts an improved magnet holder assembly for a gear position sensor unit
according to an embodiment of the present disclosure.
Figure 3 depicts a sectional view of the improved magnet holder assembly of figure 2,
according to an embodiment of the present disclosure.
Figure 4 illustrates a sectional view of the improved magnet holder assembly of
figure 2, along Section AA, according to another embodiment of the present
disclosure.
Figure 5 shows a perspective view of the clip of the magnet holder unit of the gear
position sensor unit according to another embodiment of the present disclosure.
Figure 6 shows a perspective view of the magnet holder comprising a housing and a
rotor (cover plate) according to another embodiment of the present disclosure.
Figure 7 depicts a top view of the magnet holder unit of the improved magnet holder
assembly of figure 2, according to an embodiment of the present disclosure.
6
The figures depict embodiments of the disclosure for purposes of illustration only.
One skilled in the art will readily recognize from the following description that
alternative embodiments of the structures and methods illustrated herein may be
employed without departing from the principles of the disclosure described herein.
DETAILED DESCRIPTION OF THE INVENTION
While the embodiments in the disclosure are subject to various modifications and
alternative forms, specific embodiments thereof have been shown by way of example
in the figures and will be described below. It should be understood, however that it is
not intended to limit the disclosure to the particular forms disclosed, but on the
contrary, the disclosure is to cover all modifications, equivalents, and alternative
falling within the scope of the disclosure.
It is to be noted that a person skilled in the art would be motivated from the present
disclosure and modify various constructions of an improved magnet holder assembly
for a gear position sensor unit, which may vary from vehicle to vehicle. However,
such modifications should be construed within the scope and spirit of the disclosure.
Accordingly, the drawings show only those specific details that are pertinent to
understand the embodiments of the present disclosure so as not to obscure the
disclosure with details that will be readily apparent to those of ordinary skill in the art
having benefit of the description herein.
The terms “comprises”, “comprising”, or any other variations thereof used in the
disclosure, are intended to cover a non-exclusive inclusion, such that a device,
system, assembly that comprises a list of components does not include only those
components but may include other components not expressly listed or inherent to
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such system, or assembly, or device. In other words, one or more elements in a
system or device proceeded by “comprises… a” does not, without more constraints,
preclude the existence of other elements or additional elements in the system or
device.
Accordingly, it is an aim of the present disclosure to provide an improved magnet
holder assembly to hold the magnet in magnet holder under dynamic conditions and
wide operating temperature range in oil medium and restrict the rotary movement of
the magnet holder in the rotor.
The present disclosure provides an improved magnet holder assembly for a gear
position sensor unit. The said assembly comprises a housing, a rotor coupled with a
gearbox and a magnet holder mounted in the housing. The magnet holder comprises a
pocket for holding a magnet. An elongated shaft being received concentrically in a
slot of the rotor, and at least one rib formed externally on the elongated shaft to
engage with a corresponding recess of the slot of the rotor to restrict its relative
movement. A clip is mounted resiliently between the elongated shaft and the slot of
the rotor; and a PCB assembly is configured in the housing. The elongated shaft of
the magnet holder unit has at least one flat primary side wall, two L-shaped secondary
side walls and a semi-circular peripheral wall. The slot of the rotor is in conformity
with shape and size of the elongated shaft of the magnet holder unit. The elongated
shaft comprises a threaded groove for securing the rotor with the magnet holder unit
by means of a screw. The clip has a ‘L-shape’ having a long arm and a short arm. The
long arm of the clip has a curved portion; the curved portion being disposed between
the primary side wall of the magnet holder unit and the slot of the rotor to maintain a
resilient force on the elongated shaft and restrict rotation of the magnet holder inside
the rotor. The short arm of the clip has a hole for receiving the screw; and a circular
flared projection extending inwardly towards the elongated shaft of the magnet holder
8
unit. The PCB assembly comprises a Hall IC disposed below the magnet, in the
housing; and a PCB being connected with the Hall IC.
Now referring to figures 2 to 7, in which the figure 2 is an exemplary embodiment of
the disclosure illustrating a sectional view of the improved magnet holder assembly
(100) for a gear position sensor unit. The improved magnet holder assembly provided
in the present disclosure restricts rotation of the magnet holder about its axis and XY-
Z axial movement of the magnet holder in the rotor, against the dynamic and high
operating temperature conditions in oil medium. This is accomplished by the
provision of a clip being disposed resiliently between magnet holder and slot of the
rotor. The clip has a curved portion which always maintains a positive spring force on
the magnet holder and restricts rotation of the magnet holder inside the rotor. The clip
further comprises a circular flared projection extending inwardly, thereby ensuring
POKA-YOKE by avoiding wrong orientation of the clip during assembling of the
said gear position sensor unit.
Figures 2 to 4 depict the improved magnet holder assembly (100) for a gear position
sensor unit according to an embodiment of the present disclosure. The improved
magnet holder assembly (100) comprises a housing (1) (not shown in figure 2) having
a plurality of provisions for accommodating the various components of the said
assembly. The improved magnet holder assembly (100) further comprises a rotor (2)
being coupled with a gearbox of the vehicle. Disposed in the housing (1) is a magnet
holder (3) such that in the mounted condition the magnet holder (3) is connectable
with the rotor (2). The magnet holder (3) comprises a pocket (3a) for holding a
magnet (4). The magnet holder further comprises an elongated shaft (3b) extending in
the longitudinal direction. The term ‘longitudinal direction’ herein refers to a
direction along Y-axis of the improved magnet holder assembly. The said elongated
shaft (3b) is received concentrically in a slot (2a) in the rotor (2) so as to secure the
magnet holder (3) with the rotor (2). At least one rib (3c) (not shown in figure 2) is
formed externally on the elongated shaft (3b) to engage with a corresponding recess
9
in the slot (2a) of the rotor (2), thereby restricting the relative movement of the
elongated shaft (3b) in the slot (2a) in the longitudinal direction, during operation of
the vehicle, i.e. under dynamic conditions. The slot (2a) of the rotor (2) comprises a
through hole (2b) (not shown in figure 2) for receiving a screw (6). The elongated
shaft (3b) comprises a threaded groove (3d) (not shown in figure 2)
extending in the longitudinal direction. In the mounted condition, the elongated shaft
(3b) of the magnet holder (3) is received concentrically in the slot (2a) of the rotor
(2), such that the threaded groove (3d) is disposed below the through hole (2b) (not
shown in figure 2) of the rotor (2). A clip (5) is mounted in between the elongated
shaft (3b) and the slot (2a) of the rotor (2) such that the clip (5) maintains a positive
resilient force between the magnet holder (3) and the rotor (2).
As shown in figure 4, disposed in the housing (1) is a PCB sub-assembly (7). The
PCB sub assembly (7) comprises a Hall IC (7a) being mounted below the magnet (4)
for detecting change in magnetic flux during operation of the gearbox. The said Hall
IC (7a) is mounted on a PCB (7b) such that the Hall IC (7a) is connected with the
PCB (7b).
As shown in figure 5, the clip (5) has a generally ‘L-shaped’ configuration, having a
long arm (5a) and a short arm (5b). The long arm (5a) comprises a curved portion
(5c). The short arm (5b) of the clip (5) is configured to be secured on an end (E) of
the elongated shaft (3b) which is received in the slot (2b). Accordingly, the short arm
(5b) comprises a hole (5d) for receiving the screw (6). Formed on the periphery of the
hole (5d) is a circular flared projection (5e) extending downwardly in the direction of
the long arm (5a). At the time of assembly of rotor (2) on magnet holder (3), the
flared projection (5e) avoids misalignment of clip (5) with the magnet holder (3). In
the mounted condition, the clip (5) is mounted such that the hole (5d) is aligned with
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the threaded groove (3d) of the elongated shaft (3b). In this condition, the flared
projection (5e) is extending towards the end (E) of the elongated shaft (3b).
In an embodiment of the present disclosure, as shown in figure 6, the magnet holder
assembly (3) comprises a base (B) having a closed lower end and an open upper end.
Disposed at the closed lower end is the pocket (3a) (not shown in figure 6) for
holding magnet (4). The magnet holder (3) further comprises a cover plate (C) for
locking the open upper of the base (B) and restricting movement of the magnet holder
with respect to the housing (1) during vibration in the dynamic condition. As shown
in figures 6 and 7, the elongated shaft (3b) of the magnet holder (3) has at least one
flat primary side wall (W1). Disposed at right angles, on opposite end of the primary
flat side wall (W1) are two opposite L-shaped secondary side walls (W2) such that
the secondary side walls (W2) are in mirrored orientation with one another. A
substantially semi-circular peripheral wall (W3) connects opposite ends of the
secondary side walls (W2) so as to define the elongated shaft (3b). The L-shaped
secondary side walls (W2) prevent rotary movement of magnet holder in rotor and
hence the magnet with respect to the magnet holder (3), due to vibrations in the
dynamic condition of the vehicle. The slot (2a) of the rotor (2) is in conformity with
the shape and size of the elongated shaft (3b) of the magnet holder (3). In this
condition, the long arm (5a) of the clip (5) is disposed between the primary flat side
wall (W1) and a corresponding side of the slot (2a) of the rotor (2) such that the
curved portion (5c) is under stress. As a result, a positive resilient force is applied on
the magnet holder (3) by the long arm (5a) of the clip (5). This prevents relative
movement between the magnet holder (3) and the rotor (2).
In an embodiment of the present disclosure, the magnet holder is made from a plastic
material while the rotor is made from a metallic material. In the dynamic conditions
or due to linear thermal expansion/contraction of material, when a clearance occurs
between the magnet holder (3) and the rotor (2), the circular portion (5c) applies a
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resilient force on the slot (2a) of the rotor (2) and the primary flat wall (W1) of the
elongated shaft (3), thereby restricting radial movement of the magnet holder (3) and
maintaining the sensor output characteristic signal as per specification in dynamic and
wide temperature operating conditions.
Equivalents
With respect to the use of substantially any plural and/or singular terms herein, those
having skill in the art can translate from the plural to the singular and/or from the
singular to the plural as is appropriate to the context and/or application. The various
singular/plural permutations may be expressly set forth herein for sake of clarity.
It will be understood by those within the art that, in general, terms used herein, and
especially in the appended claims (e.g., bodies of the appended claims) are generally
intended as "open" terms (e.g., the term "including" should be interpreted as
"including but not limited to," the term "having" should be interpreted as "having at
least," the term "includes" should be interpreted as "includes but is not limited to,"
etc.). It will be further understood by those within the art that if a specific number of
an introduced claim recitation is intended, such an intent will be explicitly recited in
the claim, and in the absence of such recitation no such intent is present. For
example, as an aid to understanding, the following appended claims may contain
usage of the introductory phrases "at least one" and "one or more" to introduce claim
recitations. However, the use of such phrases should not be construed to imply that
the introduction of a claim recitation by the indefinite articles "a" or "an" limits any
particular claim containing such introduced claim recitation to inventions containing
only one such recitation, even when the same claim includes the introductory phrases
"one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a"
and/or "an" should typically be interpreted to mean "at least one" or "one or more");
the same holds true for the use of definite articles used to introduce claim recitations.
12
In addition, even if a specific number of an introduced claim recitation is explicitly
recited, those skilled in the art will recognize that such recitation should typically be
interpreted to mean at least the recited number (e.g., the bare recitation of "two
recitations," without other modifiers, typically means at least two recitations, or two
or more recitations). Furthermore, in those instances where a convention analogous
to "at least one of A, B, and C, etc." is used, in general such a construction is intended
in the sense one having skill in the art would understand the convention (e.g., "a
system having at least one of A, B, and C" would include but not be limited to
systems that have A alone, B alone, C alone, A and B together, A and C together, B
and C together, and/or A, B, and C together, etc.). In those instances where a
convention analogous to "at least one of A, B, or C, etc." is used, in general such a
construction is intended in the sense one having skill in the art would understand the
convention (e.g., "a system having at least one of A, B, or C" would include but not
be limited to systems that have A alone, B alone, C alone, A and B together, A and C
together, B and C together, and/or A, B, and C together, etc.). It will be further
understood by those within the art that virtually any disjunctive word and/or phrase
presenting two or more alternative terms, whether in the description, claims, or
drawings, should be understood to contemplate the possibilities of including one of
the terms, either of the terms, or both terms. For example, the phrase "A or B" will be
understood to include the possibilities of "A" or "B" or "A and B."
While the invention has been described with reference to a preferred embodiment, it
is apparent that variations and modifications will occur without departing the spirit
and scope of the invention. It is therefore contemplated that the present disclosure
covers any and all modifications, variations or equivalents that fall within the scope
of the basic underlying principles disclosed above and claimed therein.
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Reference Numerals
100 Improved Magnet Holder Assembly
1 Housing
2 Rotor
2a Slot
3 Magnet Holder
3a Pocket
3b Elongated Shaft
3c Rib
4 Magnet
5 Clip
5a Long Arm of Clip
5b Short Arm of Clip
5c Curved Portion
5d Hole
5e Flared Projection
6 Screw
7 PCB Sub-Assembly
7a Hall IC
7b PCB
B Base
C Cover Plate
E End of Elongated Shaft
W1 Flat Primary Side Wall
W2 L-shaped Secondary Side Wall
W3 Circular Peripheral Wall
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We claim:
1. An improved magnet holder assembly (100) for a gear position sensor unit,
comprising
a housing (1);
a rotor (2) coupled with a gearbox;
a magnet holder (3) mounted in the housing (1); the magnet holder (3)
comprising;
a pocket (3a) for holding a magnet (4);
an elongated shaft (3b) being received concentrically in a slot (2a)
of the rotor (2); at least one rib (3c) formed externally on the elongated
shaft (3b) to engage with a corresponding recess in the slot (2a) of the
rotor (2) to restrict its relative movement;
a clip (5) mounted resiliently between the elongated shaft (3b) and the slot
(2a) of the rotor (2); and
a PCB sub-assembly (7) being configured in the housing (1).
2. The improved magnet holder assembly as claimed in claim 1, wherein the
elongated shaft (3b) of the magnet holder (3) has at least one primary flat side
wall (W1), two opposite L-shaped secondary side walls (W2) and a semicircular
peripheral wall (W3).
3. The improved magnet holder assembly as claimed in claim 1, wherein the slot
(2a) of the rotor (2) is in conformity with shape and size of the elongated shaft
(3b) of the magnet holder (3).
4. The improved magnet holder assembly as claimed in claim 1, wherein the
elongated shaft (3b) comprises a threaded groove (3d) for securing the rotor
(2) with the magnet holder (3) by means of a screw (6).
15
5. The improved magnet holder assembly as claimed in claim 1, wherein the clip
(5) has a ‘L-shape’ having a long arm (5a) and a short arm (5b).
6. The improved magnet holder assembly as claimed in claims 1 and 5, wherein
the long arm (5a) of the clip (5) has a curved portion (5c); the curved portion
(5c) being disposed between the primary side wall of the magnet holder and
an inner side of the slot (2a) of the rotor (2) to maintain a resilient force on the
elongated shaft (3b) and restrict rotation of the magnet holder (3) inside the
rotor (2).
7. The improved magnet holder assembly as claimed in claims 1 and 5, wherein
the short arm (5b) of the clip (5) has a hole (5d) for receiving the screw (6);
and a circular flared projection (5e) extending downwardly towards the
elongated shaft (3b) of the magnet holder (3).
8. The improved magnet holder assembly as claimed in claim 1, wherein the
PCB sub-assembly (7) comprises a Hall IC (7a) disposed below the magnet
(4) in the housing (1); and a PCB (7b) being connected with the Hall IC (7a).