WO2000030887A1

WO2000030887A1 - Potentiometer shaft for a seat motor assembly

Info

Publication number: WO2000030887A1
Application number: PCT/CA1999/001073
Authority: WO
Inventors: Ian D. Haynes; Randy Corey; Greg Prong; Pat Morgan
Original assignee: Dura Global Technologies, Inc.
Priority date: 1998-11-20
Filing date: 1999-11-16
Publication date: 2000-06-02
Also published as: JP2000158982A; AU1143500A

Abstract

A shaft for supporting a sensor in a motor assembly for a vehicle seat adjuster includes a flexible body having a first connector portion at one end and a second connector portion at an opposite end. The first connector portion is for connection to a sensor and the second connector portion is for connection to a motor drive shaft. The drive shaft (14) is used to move a seat member from a first position to a second position where the sensor determines the number of rotations of the drive shaft during seat member movement such that the seat member can be accurately moved between the first and second positions. The motor drive shaft (14) has a drive connector for receiving the second connector portion of the shaft. The second connector is flexible and self-aligning within the drive connector of the drive shaft during installation of the sensor support shaft onto the motor drive shaft (30). The drive connector has a rectangular shape and the second connector has a non-rectangular shape which facilitates assembly when the second connector is installed into the drive connector.

Description

POTENTIOMETER SHAFT FOR A SEAT MOTOR ASSEMBLY

BACKGROUND OF THE INVENTION

This application relates to a support shaft for a sensor in a seat adjuster having a motor. Specifically, the support shaft has a connector with a non-rectangular shape that is self-alignable for installation onto a motor drive shaft.

Seat adjusters are used to adjust the position of a vehicle seat between various positions. Typically, seat adjusters use electric motors to move a certain seat member between a plurality of positions. These motors often include a memory feature utilizing a sensor so that the seat can be moved from a first position to a second position and then be returned precisely to the first position. This memory feature allows a seat to be easily and quickly adjusted to accommodate drivers of varying heights. The sensor is typically a potentiometer that counts how many rotations a drive shaft in the motor has experienced in moving the seat member from one position to the next. The same number of counts in the reversed rotational direction will be used to return the seat member to its original position.

The potentiometer is supported on a support shaft that is installed for rotation with the motor drive shaft. The motor drive shaft typically has a rectangular shaped hole that receives a rectangular shaped extension on one end of the support shaft. The installation of the support shaft onto the drive shaft is often a blind assembly, which means that the rectangular extension has to be properly aligned with the rectangular hole for successful installation. If the rectangular extension is misaligned with the rectangular hole, the support shaft may break when force is applied to the shaft to force it in the hole. This results in significant material waste. The installation process is also expensive because additional time is required to try to properly align the extension with the hole and additional time is needed to install a second support shaft if the first support shaft has been broken during assembly.

Thus, it is desirable to provide a shaft for supporting a sensor that is self- aligning and which can be easily installed onto a motor drive shaft during blind assembly. By eliminating the use of a rectangular shaped connector, material costs are reduced and assembly time is decreased. SUMMARY OF THE INVENTION

A shaft for supporting a sensor in a motor assembly for a vehicle seat adjuster includes a flexible body having a first connector portion at one end and a second connector portion at an opposite end. The first connector portion is for connection to a sensor and the second connector portion is for connection to a motor drive shaft. The drive shaft is used to move a seat member from a first position to a second position where the sensor determines the number of rotations of the drive shaft during seat member movement such that the seat member can be accurately moved between the first and second positions. The motor drive shaft has a drive connector for receiving the second connector portion of the shaft. The second connector is flexible and self- aligning within the drive connector of the drive shaft during installation of the sensor support shaft onto the motor drive shaft.

In one embodiment, the second connector portion defines a center and has a plurality of extensions extending out radially from the center. The drive connector has a rectangular aperture for receiving the extensions. During installation of the second connector onto the drive shaft, if the extensions are misaligned with the aperture, the extensions flex until the extensions become aligned within the aperture. Once properly aligned, the extensions are inserted into the aperture and the shaft is operably connected to the motor drive shaft. Using a flexible connector portion for installation of a sensor support shaft onto a motor drive shaft decreases assembly time and cost. The use of this improved shaft also decreases material costs. These and other features can be understood from the following specification and drawings.

BRIEF DESCRIP ION OF THE DRAWINGS

Figure 1 is a schematic view of a motor assembly in a seat adjuster including the subject support shaft.

Figure 2 is a perspective view of the support shaft. Figure 3 is a side view of the support shaft shown in Figure 2. Figure 4 is a cross sectional view taken along line 4-4 in Figure 3. Figure 5 is an end view of a motor drive shaft connector for receiving the subject support shaft.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A motor assembly for operating a seat adjustment mechanism is shown generally at 10 in Figure 1. The motor assembly includes an electric motor 12 having a drive shaft 14 defining an axis of rotation 16. The drive shaft is connected to a seat adjustment member 18, shown schematically, which is movable between a plurality of positions. The seat adjustment member 18 can be used to adjust a vehicle seat 19, shown schematically, in a vertical or horizontal direction, for example.

An actuator 20 is used to send a signal to the motor 12 to rotate the drive shaft 14 to move the seat adjustment member 18 from a first position to a second position. The actuator 20 is operated by a seat occupant to adjust the position of the seat to a desired seating position. When activated by the seat occupant, the actuator 20 sends a signal to activate the motor, which causes the drive shaft 14 to rotate resulting in the movement of the seat adjustment member 18. A flexible cable 22 is preferably used to connect the drive shaft 14 to the seat adjustment member 18, however, other connection methods could also be used.

The motor assembly 10 includes a memory feature utilizing a sensor 24 for controlling the movement of the seat from a first position to a second position. The memory feature allows the seat to be returned precisely to the first position. This memory feature allows a seat to be easily and quickly adjusted to accommodate drivers of varying heights. The sensor 24 is preferably a potentiometer that counts how many times the drive shaft 14 has rotated about the axis of rotation 16 in moving the seat adjustment member 18 from a preset first position to a second position. The same number of counts in the reverse rotational direction will be used to return the seat adjustment member 18 to its original preset, or memory, position. While a potentiometer is the preferred sensor 24 for the memory feature, it should be understood that any similar sensor known in the art could also be used. A support shaft 30 is used to support the potentiometer 24 with respect to the drive shaft 14. The support shaft 30, shown in greater detail in Figure 2, has a first end 34 and a second end 36. The first end 34 is installed within the potentiometer 24 while the second end 36 is connected to the drive shaft 14.

As shown in Figure 3, the drive shaft 14 has a connector portion 26 with a first receiver 28 having a first shape with a rectangular cross-sectional area. The first receiver 28 is preferably an aperture having a rectangular outline, seen in the cross- sectional view in Figure 5. At the second end 36 of the support shaft 30 is a second receiver 32 that has a second shape with a non-rectangular cross-sectional area. The second receiver 32 is preferably an extension 32 having a non-rectangular shape that mates with the rectangular shape of the outline of the aperture 28, seen in the cross- sectional view in Figure 4. To connect the support shaft 30 to the drive shaft 14, the extension 32 is pushed into the aperture 28. Once connected, the drive shaft 14 and the support shaft 30 rotate together.

The non-rectangular shaped extension 32 is easily alignable with the aperture 28 which improves the assembly process for connecting the support shaft 30 to the drive shaft 14. This assembly process is a blind assembly process so the first 28 and second 30 receivers must be easily alignable with one another. W ile the first receiver 28 is preferably an aperture or female connector and the second receiver 32 is preferably an extension or male connector, the reverse can also be used where the first receiver 28 is a male connector and the second receiver 32 is a female connector. The support shaft 30 is preferably made from a flexible material, such as a soft plastic. Specifically, the second receiver 32 portion of the support shaft 30 should be made from a flexible material so that the support shaft 30 is self-aligning when installed into the aperture 28. This will be discussed in greater detail below.

As shown in Figures 4 and 5, the extension 32 and the aperture 28 each define a first central axis 38 and a second central axis 40 that is peφendicular to the first central axis 38. The shapes of the extension 32 and the aperture 28 are preferably symmetrical about the first 38 and second axes 40 to make installation of the extension 32 into the aperture 28 easier.

The shape of the extensions 32 preferably includes a center 42 with a plurality of fingers 44 extending radially outwardly from the center 42. The fingers 44 are separated from each other by curved surfaces 46. The extension 32 has solid fingers that are flexible. The solid fingers 44 of the extension 32 are slidably engaged in the rectangular aperture 28 when the support shaft 30 is connected to the drive shaft 14. In the preferred embodiment, four (4) fingers are shown, two (2) on each side of each of the axes 38, 40. While four fingers 44 are preferred, a greater or lesser amount of fingers 44 could be used.

As discussed above, the extension 32 that makes up the second receiver portion 32 of the support shaft 30 is made from a flexible material. The connector portion 26 is made from a less flexible material. Thus, each of the fingers 44 on the extension 32 has the capability of flexing or bending during installation if they contact a portion of connector portion 26. Each fmger 44 preferably extends outwardly to a pointed tip 48. If the fingers 44 are misaligned with the aperture 28, as force is applied to push the extension 32 into the aperture 28, the fingers 44 will bend and flex causing the support shaft 30 to rotate until the fingers 44 are aligned within the aperture 28. The fingers 44 will bend more near the tip 48 than near the center 42 where the fingers 44 are thicker. Once the fingers 44 are properly aligned within the aperture 28, the extension 32 can be fully installed within the aperture 28. This feature is described as a self-indexing or self-aligning feature, which means that during assembly of the support shaft 30 onto the drive shaft 14, the extension 32 on the support shaft 30 will automatically cause the support shaft 32 to rotate under load until the shaft 30 is properly aligned with the first receiver aperture 28 on the drive shaft 14.

The extension 32 preferably has a rounded end 50, shown more clearly in Figure 3, which assists in aligning the extension 32 within the aperture 28. Having self-aligning or self-indexing capability for installation of the sensor support shaft 32 into the drive shaft 14 decreases assembly time. Support shafts that are not self- indexing often break under load as they are being installed under misaligned conditions. Thus, self-aligning support shafts 30 also result in a material cost savings as fewer parts are scrapped.

Preferred embodiments of this invention have been disclosed, however, a worker of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention. For that reason the following claims should be studied to determine the true scope and content of this invention.

Claims

CLAIMSWe claim:

1. A motor assembly for operating a seat adjustment mechanism comprising: an electric motor having a drive shaft defining an axis of rotation and including a connector portion with a first receiver having a first shape; an actuator for sending a signal to said motor to rotate said drive shaft to move a seat member from at least a first position to a second position; a sensor for determining the number of rotations of said drive shaft about said axis of rotation such that the seat member can be accurately moved from said first position to said second position; and a support shaft for supporting said sensor having a second receiver with a second shape with a non-rectangular cross-sectional area such that when said support shaft is connected to said drive shaft said second receiver is easily alignable with said first receiver.

2. An assembly as recited in claim 1 wherein said first receiver is an aperture and said second receiver is an extension, said extension being received in said aperture when said support shaft is installed on said drive shaft.

3. An assembly as recited in claim 2 wherein said first and second shapes have a first central axis and a second central axis that is peφendicular to said first central axis, said first and second shapes being symmetrical about said first and second axes.

4. An assembly as recited in claim 2 wherein said first shape is rectangular and said second shape includes a center with a plurality of fingers extending radially outwardly from said center.

5. An assembly as recited in claim 4 wherein said fingers are separated from each other by curved surfaces.

6. An assembly as recited in claim 5 wherein each of said fingers includes a pointed tip.

7. An assembly as recited in claim 2 wherein said extension has a rounded end such that said extension is self-alignable within said aperture.

8. An assembly as recited in claim 1 wherein said support shaft is more flexible than said first receiver.

9. An assembly as recited in claim 1 wherein said sensor is a potentiometer.

10. A motor assembly for operating a seat adjustment mechanism comprising: an electric motor having a drive shaft defining an axis of rotation and including a first connector having a first shape; an actuator for sending a signal to said motor to rotate said drive shaft to move a seat member from at least a first position to a second position; a sensor for determining the number of rotations of said drive shaft about said axis of rotation such that the seat member can be accurately moved from said first position to said second position; and a flexible support shaft for supporting said sensor having a second connector with a second shape with a non-rectangular cross-sectional area such that during installation of said support shaft onto said drive shaft said second connector is self- alignable with said first connector.

11. An assembly as recited in claim 10 wherein said first connector is a female connector, said second connector is a male connector, and first shape having a rectangular outline and said second shapes defining a center with a plurality of fingers extending out radially from said center, said fingers being separated from one another by curved portions.

12. An assembly as recited in claim 11 wherein said fingers of said male connector are solid finger-shaped extensions having a base that extends outwardly to a tip, said base being wider than said tip.

13. An assembly as recited in claim 12 wherein said finger-shaped extensions are more flexible at said tip than at said base such that during installation of said male connector into said female connector said tips flex until said extensions become aligned within said aperture.

14. An assembly as recited in claim 10 wherein said sensor is a potentiometer.