JPH01275961A - Backlash eliminator for speed increasing and reduction gear mechanism - Google Patents

Abstract

PURPOSE:To prevent a variation of preload force in a gear contact part from occurring by making an elastic member, being interposed between a bearing supporting a shaft and a bearing pocket, so as to give the preload force to the gear contact part. CONSTITUTION:Ball bearings 23, 24 supporting both side ends of a contershaft 20 are assembled in bearing pockets 42, 52 between each bearing cover 40 and a gearbox 50b after fitting an elastic member 25 of gum or the like on the outer circumferential surface. Preload force by displacement of the elastic member 25 is added to a contact part between a driving gear 11 and a first countershaft 21 as well as another contact part between an output gear 32 and a second countershaft 22, so that such an engaged state as having no backlash is thus kept up.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a backlash removal device for a speed increasing/decelerating gear mechanism in a transmission power steering of a vehicle or in various other industrial machines.

If there is a structure that does not have a structure to eliminate backlash, the accuracy of each gear must be improved and processed.
Furthermore, even when assembled with selected combinations, it is difficult to completely eliminate backlash, and backlash increases due to wear of the tooth surfaces during use, causing abnormal noises due to collisions between gears. This impairs the steering feeling.

Therefore, various proposals have been made regarding backlash removal means for this type of power transmission device.
In Publication No. 73, a shaft (output shaft) that transmits force from a steering wheel to a steering mechanism and a drive gear (output gear) that rotates around the shaft are connected via a torque transmission member, and this drive gear and a torque transmission member are coupled by a buffer member made of vulcanized rubber, and the driving force transmitted from the pinion gear (drive gear) of the motor to the drive gear of the shaft via the first and second intermediate gears is transferred to the buffer member and the torque. The structure is such that the rotation is transmitted to the shaft via the transmission member.

Since the buffer member provided between the shaft and the drive gear rotates together with the drive gear, eccentricity occurs in the drive gear, causing fluctuations in the preload force at the meshing part between the drive gear and the intermediate gear that meshes with it. As a result, there are disadvantages in that problems such as a decrease in rotation accuracy due to torque unevenness and an increase in vibration noise occur.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate such drawbacks and provide a backlash removal device that does not cause fluctuations in the preload force applied to the meshing portion of the gear.

[Means to solve the problem]

In order to achieve the above object, in the present invention, a bearing pocket in which a bearing supporting the shaft of one of the at least two gears constituting the speed increasing/decelerating gear mechanism is accommodated, the other gear is The bearing pocket that accommodates the bearing that supports the shaft of the gear is set so that the dimension between the centers of both bearing pockets is slightly smaller than the dimension between the centers of the gears when both gears are engaged without backlash. The outer circumferential surface of a bearing that supports at least one shaft is assembled into the bearing pocket via an elastic member.

It is preferable to use the above-mentioned elastic member whose outer peripheral edge is shaped into an elliptical shape, an oblong shape, etc., and arrange the elastic member so that the major diameter direction of the elastic member coincides with the direction between the shafts of both gears. .

[Function] In the speed increasing/decelerating gear mechanism assembled with the above arrangement, the elastic member interposed between the bearing that supports at least one shaft and the bearing pocket,
It is displaced by an amount corresponding to the difference between the gear center-to-center dimension and the bearing center-to-center dimension to apply a preload force to the meshing portions of the gears that are meshed with each other.

[Embodiment] FIG. 1 is a longitudinal sectional side view showing a power transmission device for electric power steering as an example of a device equipped with a reduction gear mechanism to which the present invention is applied.

The rotational force of the drive motor 1 is transferred from the drive gear 1 fixed to the drive motor shaft 10 to the drive gear 1 fixed to the intermediate shaft 20.
) is transmitted to the output gear 32 that meshes with the second intermediate gear 22 of the intermediate shaft 20, thereby forming a mechanism in which the output shaft 30 rotates at a reduced speed. Both ends of the drive motor shaft 10 are provided with ball bearings 13 housed in a bearing cover 40 and a bearing box 50a that constitute a housing.
14, both ends of the intermediate shaft 20 are also rotatably supported by ball bearings 23, 24, which are similarly housed in the bearing cover 40 and the gear box 5b, and both ends of the output shaft 3o is rotatably supported by ball bearings 33, 34 housed in the gearbox 50b.

The configuration of each part other than the above is not directly related to the present invention, and therefore a description thereof will be omitted.

Figure 2 shows the center-to-center dimension A of the gears when the gears, shafts, and bearings are meshed with each other without any crush when the present invention is applied to the reduction gear mechanism having the above configuration.
is equal to the sum (A+B) of the center-to-center dimension B of the output gear 32 and the second intermediate gear 22 when they are meshed without backlash.

A bearing pocket 42 of a bearing cover 40 in which a ball bearing 23 that supports the end of the first intermediate gear 21 of the intermediate shaft 20 is accommodated.
For example, the distance between the pocket centers of this bearing pocket 42 and the bearing pocket 41 of the bearing cover 40 in which the ball bearing I3 that supports the end of the drive motor shaft 10 is housed, with the ball bearing 13 side of the drive motor shaft 10 as a reference. Dimension C is the drive gear 1)
and the first intermediate gear 21 are provided at a position set to be slightly smaller than the gear center-to-center dimension A when the gears and the first intermediate gear 21 are engaged with each other without backlash.

Furthermore, the bearing pocket 52 of the gear box 50b, which accommodates the ball bearing 24 that supports the end of the intermediate shaft 20 on the second intermediate gear 22 side, is connected to the bearing pocket 52 and the ball bearing that supports the end of the output shaft 30. 34 is housed in the gear box 50b
The pocket center dimension between the bearing pocket 51 and the ball bearing 33 side of the output shaft 30 is defined as the gear center distance when the output gear 32 and the second intermediate gear 22 are meshed with each other without backlash. It is provided at a position set slightly smaller than dimension B.

As shown in FIGS. 3 and 4, the ball bearings 23 and 24 that support both ends of the intermediate shaft 20 are fitted with elastic members 25 made of rubber or the like on their outer circumferential surfaces to support each bearing. It is assembled into the bearing pockets 42, 52 of the cover 40 and the gear box 50b. The elastic member 25 shown in FIG.
One ball bearing 23 is fitted into the inner circumferential surface of ball bearing 6.
In the case of the other ball bearing 24, the longer diameter direction of the elastic member 25 coincides with the interaxial direction between the intermediate shaft 20 and the drive motor shaft 10, and the longer diameter direction of the elastic member 25 of the other ball bearing 24 coincides with the drive gear 1). At the meshing portion with the first intermediate gear 21, an elastic member 2 of a ball bearing 23 supporting the end of the intermediate shaft 20 on the first intermediate gear 21 side is provided.
5 displacement (drive gear 1), the gear center-to-center dimension A of the first intermediate gear 21, and the ball bearing 13 that supports the drive motor shaft 10.
and the bearing pocket center-to-center dimension C of the ball bearing 23 that supports the intermediate shaft 20) is applied to maintain a meshing state without backlash, and the output gear 32
The second intermediate shaft 20 has a meshing portion with the second intermediate gear 22 and the second intermediate gear 22 .
Displacement of the elastic member 25 of the ball bearing 24 that supports the end of the intermediate gear 22 (dimension B between the gear centers of the output gear 32 and the second intermediate gear 22, and the ball bearing 33 that supports the output shaft 30 and the intermediate shaft) A preload force is applied due to the difference between the ball bearing 24 supporting the ball bearing 20 and the center-to-center dimension of the bearing pocket, thereby maintaining a meshing state without backlash.

Elastic member 25 of ball bearing 23, 24 supporting intermediate shaft 20
The outer peripheral edge is formed into an elliptical shape, and the rigidity in the major axis direction is smaller than the rigidity in the minor axis direction, so it is easier to displace in the major axis direction than in the minor axis direction, and is necessary for the meshing part of each gear. Moreover, sufficient preload force can be applied. The shape of the outer peripheral edge of the elastic member 25 is not limited to an elliptical shape, but can be formed into an elliptical shape or any other similar shape.

In the embodiment described above, a case has been described in which backlash removal means are provided in both the meshing portion between the drive gear 1) and the first intermediate gear 21 and the meshing portion between the output gear 32 and the second intermediate gear 22. The present invention can also be applied to the case where backlash of one of the meshing portions is removed.

Further, although the present invention is limited to the reduction gear mechanism of electric power steering explained in the above embodiment, the mechanism is not limited to that of the above embodiment, and the intermediate shaft is omitted and the rotation of the drive motor shaft is directly transferred to the output shaft It may also be a gear mechanism that transmits the signal to the user.

〔Effect of the invention〕

As explained above, according to the present invention, a preload force is applied to the meshing portion of the gear by the displacement of the elastic member interposed between the outer peripheral surface of the bearing that supports the shaft of the gear and the bearing pocket.
Even if the gears and bearing pockets are machined with relatively low precision, or even if the tooth surfaces of the gears are worn during use, the predetermined preload can be applied, and the elastic Since the member itself does not rotate and only applies preload force, a hacklanche removing device is obtained in which the preload force does not fluctuate and the rotation accuracy of the gear does not deteriorate.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional side view showing a power transmission device for electric power steering, FIG. 2 is a layout diagram of a wave gear mechanism according to the present invention, and FIG. 3 is a sectional view of a ball bearing that supports an intermediate shaft.
FIG. 4 is a front view thereof. In the figure, 10 is the drive motor shaft, 1) is the drive gear, the output shaft,
32 is the output gear, 34 is the ball bearing of the output shaft, 41 is the bearing pocket of the ball bearing of the drive motor shaft, 51 is the bearing pocket of the ball bearing of the output shaft, and A is the gear center distance between the drive gear and the first intermediate gear. B is the dimension between the gear centers of the output gear and the second intermediate gear, C is the dimension between the bearing pocket centers of the drive motor shaft bearing and the intermediate shaft bearing, and D is the dimension between the output shaft bearing and the intermediate shaft bearing. This is the center-to-center dimension of the bearing pocket. Patent applicant: NSK Ltd. Figure 1 Figure 2

Claims (2)

[Claims] (1) Speed increase achieved by meshing at least two gears
In a reduction gear mechanism, a bearing pocket that accommodates a bearing that supports the shaft of one gear that is engaged is placed between the centers of both bearing pockets, and a bearing pocket that accommodates a bearing that supports the shaft of the other gear. The dimensions are set slightly smaller than the gear center-to-center dimension when both gears are engaged without backlash, and the outer peripheral surface of the bearing that supports at least one shaft is assembled into the bearing pocket via an elastic member. A backlash removal device for a speed increasing/decelerating gear mechanism, which is characterized by the following. (2) The back of the speed increasing/reducing gear mechanism according to claim (1), wherein the outer peripheral edge of the elastic member is formed into an elliptical shape, and the elastic member is assembled so that its major diameter direction coincides with the interaxial direction of the shafts of both gears. Lash removal device.