JPS63263169A - Reduction gear - Google Patents

Abstract

PURPOSE:To obtain a reduction gear which can eliminate backlash between teeth even when normal and reverse rotations are frequently carried out by combining two helical gears placed on one axis with a pair of intermediate shaft gears each having a helical gear structure which are placed in parallel to said axis. CONSTITUTION:First and second helical gears 4, 8 for transmitting the rotation output of a motor 2 to the output shaft 7 of a reduction gear 1 are placed on one axis, and a pair of intermediate shaft gears 5, 6 are placed in parallel to the axis of these helical gears 4, 8. The intermediate shaft gears 5, 6 consist of first stage and second stage helical gears 5a, 6a and 5b, 6b which are engaged with the helical gears 4, 8 respectively, and the intermediate gears 5 and 6 are formed as systems for transmitting the torques at the times of left rotation and right rotation of the helical gear 4 to the helical gear 8, respectively. Also, the helical gears 4, 8, 5a-6b are set in such a way that the directions of torsion of the gears are alternately differentiated, while providing an adjusting mechanism 23 for movingly adjusting one of the pair of intermediate gears 5, 6 in the axial direction.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a reduction gear that reduces the output of an electric motor and increases torque, and is particularly suitable for use in a steering transmission mechanism of an electric power steering device. This relates to a reduction gear.

[Conventional technology]

Generally, an electric power steering device uses a torque sensor to detect the torsional torque generated on the steering shaft when the steering wheel is turned, and outputs an output from the electric motor corresponding to the detected value via a reduction gear, and this output is transmitted to the driver. It is used as an assist force to assist the steering force of the vehicle, and the reducer is usually a planetary gear type,
A two-axis gear type is used.

As is well known, this type of reducer has the function of reducing the output of the electric motor and increasing the torque, and also ensures backlash between the reduction gears to prevent gear assembly due to gear errors. Consideration has been given to prevention of problems, ease of assembly, etc.

Incidentally, such backlash is caused especially when a reduction gear is used in a power steering device, because the gears thereof often rotate left and right in response to the rotation of the electric motor that responds to left and right turning of the steering wheel. This was causing vibration and noise when the rudder was turned. Therefore, conventionally, for example, Japanese Patent Application Laid-Open No. 61-196860
In a planetary gear type reduction mechanism, etc., as disclosed in the above publication.

A method has been proposed in which an elastic member is interposed in a gear component to absorb vibration noise generated between gears of a speed reduction mechanism.

[Problem that the invention seeks to solve]

As mentioned above, attempts have been made in the past to incorporate vibration absorbing means such as elastic members into a part of the gear to absorb vibration noise caused by backlash. However, it is difficult to eliminate the vibration noise itself, which is the source of vibration noise. Therefore, for devices such as power steering gear reducers where gears frequently rotate from side to side, it is difficult to eliminate the vibration noise caused by vibration noise. It is difficult to eliminate this problem to the extent that it occurs, and sufficient consideration has not been given to the fact that the steering response of the steering wheel is delayed by the amount of backlash.

The present invention has been made in view of the above points.

The purpose of this is to eliminate backlash between gears in any direction of rotation without any trouble by simple adjustment, even in a mechanism where the gears of the reducer frequently rotate from side to side, thereby reducing noise. The object of the present invention is to provide a speed reducer with excellent speed reduction and operational response.

Measures to solve problem C] The above objective is achieved as follows. below.

In order to facilitate understanding of the content of the present invention, FIG.

The explanation will be made by referring to the reference numerals of the embodiment shown in FIG. Sunarichi,
In order to achieve the above object, the present invention provides that the first helical gear 4 and the second helical gear 8 that transmit the rotational output of the electric motor 2 to the output shaft 7 of the reduction gear 1 are arranged on the same @ line. 1. A pair of intermediate shaft gears 5 and 6 are arranged parallel to the axes of the second helical gears 4 and 8, and each intermediate shaft gear 5 and 6 meshes with the first helical gear 4, respectively. Consisting of first stage helical gears 5a, 6a for deceleration, and second stage helical gears 5b, 6b meshing with the second helical gear 8,
One intermediate shaft gear 5 of the pair of intermediate shaft gears 5 and 6 transmits the torque when the first beveled gear 4 rotates to the left to the second helical gear 8, and the other intermediate shaft gear The system is such that the shaft gear 6 transmits the torque when the first bevel gear 4 rotates clockwise to the second bevel gear 8, and the first. The second bevel gear 4°8 and the first stage and second stage helical gears 5a and 6a
.

5b and 6b are mechanisms 23 that are set so that the twisting directions of the gears are alternately different, and that move and adjust at least one of the pair of intermediate shaft gears 5 and 6 in the axial direction.
will be established.

[Effect]

According to the present invention having such a configuration, for example, by counterclockwise rotation of the motor output shaft 3, the first helical gear 4 is rotated as seen from the output shaft 7 side as shown by the solid arrow in FIG. 2(b). When it rotates to the left, this rotational torque is applied to one intermediate shaft gear 5.
The torque is transmitted to the second helical gear 8 through the first and second stage helical gears 5a and 5b, causing the gear 8 to rotate counterclockwise, and finally the output shaft 7 is decelerated and torque is increased. Achieved as left rotation torque. Conversely, when the rotation of the electric motor changes and the first helical gear 4 rotates in the opposite direction to the arrow in FIG. The first shaft gear 6. 2nd stage helical gears 6a, 6
b to the second helical gear 8, and finally to the output shaft 7 as clockwise rotation torque which is decelerated and torque increased.

In this way, when the rotation of the electric motor 2 is switched from, for example, left rotation to right rotation, if the final integrated backlash fn is as shown in FIG. If it is located between the first stage helical gear 6a and the first stage helical gear 6a, it will cause vibration noise and delay in torque transmission. In the present invention,
This kind of data congestion can be resolved as follows. That is, the intermediate shaft gear 6 is moved through the axial movement adjustment mechanism 23.
When is moved by a distance S in the direction of arrow A, it becomes as shown in Fig. 2 (a
), each gear 4, 5a, 5b, as shown by the diagonal block on each gear (the diagonal block stands on the face of each gear and represents the twisting direction of the gear).

Since gears 6a, 6b, and 8 are twisted in different directions alternately, the gears with no back cracks receive the pushing force when the intermediate shaft gear 6 moves in the axial direction, and sequentially transmit slight rotational torque ( In this example, the second helical gear 8 receives the pushing force of the intermediate shaft gear 6b and rotates slightly in the direction of the dashed arrow in FIG. 2(b).
The slight rotational torque of this gear 8 is transmitted to the second stage helical gear 5b → first stage helical gear 5a → first stage helical gear 4), and finally to the first stage helical gear 4. The gear 4 slightly rotates in a direction to eliminate the gap between the intermediate shaft gear 6 and the first stage helical gear 6a. As a result, this slight rotational torque transmission and the intermediate shaft gear 6
The accumulated back crack fn is eliminated by the cooperative action with the axial movement of fn.

It should be noted that the occurrence of back crack fn can be eliminated by adjusting the movement of the intermediate shaft gear in the same manner as described above. This point will be discussed in the [Example] section.

(Example) An embodiment of the present invention will be explained based on Figs. 1 to 5. Fig. 1 is a partially cutaway sectional view of a speed reducer as an embodiment of the present invention, and Figs. 2 to 4 is an explanatory diagram showing the operating principle of this embodiment, and FIG. 5 is a configuration diagram of an electric power steering device to which this embodiment is applied.

Prior to explaining the reduction gear, an overview of the electric power steering device will be explained based on FIG. 5. As shown in FIG. The torque sensor 26 provided in
transmits electric power from the battery 28 to the electric motor 2 in accordance with the signal from the torque sensor 26 to drive the electric motor 2. Electric motor 2
The generated torque is decelerated and increased by reducer 1, and pinion 2
9, the rack 30 is moved with the help of the operating force of the steering handle 25, and the direction of the tires 31 is changed.

Next, the reduction gear 1 of this embodiment used in the power steering device will be explained based on FIGS. 1 to 4.

The speed reducer 1 is constructed integrally with an electric motor 2 as shown in FIG.
, a pair of intermediate shaft gears 5 and 6, and a serpentine gear 8 provided on the output shaft 7 of the reduction gear. These gear elements are connected to brackets 9 and 10 that constitute the housing of the reducer 1.
．． It is incorporated in 11. That is, the output shaft 3 of the electric motor 2 having the helical gear 4 is supported at one end by a bearing 12 in the bracket 11, and the other end is assembled into one end of the output shaft 7 disposed on the same axis as the output shaft 3. The bearing 13 is supported by a bearing 13. Also.

The intermediate shaft gear 5 includes a first stage deceleration helical gear 5a and a second stage helical gear 5b, and the intermediate shaft gear 6 includes:
It is composed of a first stage deceleration bevel gear 6a and a second stage helical gear 6b, and each intermediate shaft gear 5, 6 is connected to a bracket 9,
1o, and is arranged axially parallel to the output shaft 3 of the electric motor 2 and the output shaft 7 of the reducer 1, and the respective first stage helical gears 5a and 6a are connected to the helical gear 4 of the motor output shaft 3. The second stage helical gears 5b and 6b mesh with the helical gear 8 of the reducer output shaft 7. An output shaft 7 having a helical gear 8 has a metal 1 press-fitted into one end of a bracket 10.
8.19 and washer 20. The axial position is fixed via a C-shaped retaining ring 21.

Here, based on FIGS. 2(a) and (b), each gear element 4,
5a, 5b, 6a, 6b, and 8 will be explained. The hatched blocks on each gear shown in FIG. 2 schematically represent the meshing state of each gear when standing on the surface of these gears. The helical gear 4 of the motor output shaft 3 has a helix angle set to 11 degrees to the right, and of the pair of intermediate shaft gears 5 and 6 that mesh with the helical gear 4, the first gear has the largest number of teeth. The stepped helical gears 5a, 6a have a helix angle of 11° to the left, and the second stage helical gears 5b, 6b have fewer teeth than the first stage helical gears 5a, 6a. Contrary to the step helical gear, the helix angle is set to 11" to the right, and the helical gear 8 provided on the output shaft 7 has a helix angle set to 11" to the left.

Next, returning to FIG. 1 and explaining, a pair of intermediate shaft gears 5, 6
Among them, one intermediate shaft gear 6 can be adjusted to move in the axial direction as follows. That is, a space 22 for movement is secured between the bearing 16 that supports one end of the intermediate shaft gear 6 and the bracket 9, and the bearing 17 that supports the other end is press-fitted into the intermediate shaft 6'.
The end of the bearing 17 is held down by the holding member 23.

A screw 24 is cut on the outer periphery of the presser member 23, and with this configuration, when the presser member 23 is rotated,
The intermediate shaft gear 6 moves in the axial direction.

Next, the operation of the reduction gear of this embodiment will be explained.

First, an overview of the operation of the reducer will be described.

In the reducer 1 of this embodiment, one of the pair of intermediate shaft gears 5 and 6 is configured in advance to control the left rotation of the helical gear (as viewed from the output shaft 7 side). 8, and the other intermediate shaft gear 6.

This is a system for transmitting clockwise rotation of a helical gear 8 to an output shaft 7.

Under these conditions, when the output shaft 3 of the electric motor 2 rotates to the left when viewed from the reducer output shaft 7 side, the torque generated in the electric motor 2 is transferred to the motor output shaft as shown in FIG. 2(b). 3, the left tooth flank of the helical gear 4 (The left and right sides of the tooth flank are expressed from the axis of each gear itself. The same applies hereinafter.)
Torque is transmitted to the left tooth surface of the first stage helical gear 5a of the intermediate shaft gear 5, and is further transmitted from the right tooth surface of the second stage helical gear 5b to the right tooth surface of the helical gear 8. It is transmitted to the output shaft 7 and extracted as power (clockwise rotation).

The rotation direction at this time is the direction of the solid line arrow in FIG. The deceleration is increased by the gear ratio of the gear 5b and the bevel gear 8 and output. Further, a part of the output of the output shaft 7 at this time is transmitted to the second stage helical gear 6b of the other intermediate shaft gear 6 via the helical gear 8, and the intermediate shaft gear 6 also rotates. .

Next, when the output shaft 3 of the electric motor 2 rotates clockwise as viewed from the reducer output shaft 7, the right tooth surface of the helical gear 4 of the output shaft 3 will move from the right tooth surface of the first helical gear 6a of the intermediate shaft gear 6. Torque is transmitted to the tooth surfaces, further transmitted from the left tooth surface of the second stage helical gear 6b to the left tooth surface of the helical gear 8, and is extracted as power (clockwise rotation).

In addition, at this time, a part of the output of the output shaft 7 is transmitted via the helical gear 8 to the second stage helical gear 5b of the other intermediate shaft gear 5.
The intermediate shaft gear 5 also rotates.

As described above, the speed reducer 1 in this embodiment is as follows.

Intermediate shaft gear 5 depending on the left and right rotational direction of motor output shaft 3
, 6 transmission systems can be used. Here, the motor output shaft 3 is currently rotating to the left, and the gear 4 → the first stage gear 5a → the second gear
Power is transmitted through the system of step gear 5b → gear 8, and at this time, the final result is the accumulation of backlash between each gear, called backlash fn.
Assume that the first stage of the intermediate shaft is located between the helical gear 6a and the helical gear 4 of the motor output shaft 3. If the rotational direction of the motor output shaft 3 is reversed (clockwise) in this state, the responsiveness of torque transmission will be delayed by the amount of accumulated backlash fn, and noise will be generated when the gears mesh by the amount of backlash. do. In this embodiment, such a problem is resolved by performing the following patch crush adjustment.

That is, when the accumulated backlash fn has occurred, the intermediate shaft gear 6 is pressed in the axial direction (in the direction of arrow A) by the holding member 23 shown in FIG.
When the gear is moved a distance of Then, the helical gear 8 rotates slightly in the direction of the dashed arrow in FIG. 2(b), and this rotation torque is finally transmitted to the helical gear 4 of the motor output shaft 3 via the intermediate shaft gear 5. The helical gear 4 slightly rotates to the right, and the right tooth flank of the helical gear 4 moves in a direction in which it comes into contact with the right tooth flank of the first stage helical gear 6a of the intermediate shaft, which is in a non-rotating state. death,
The integrated backlash fn can be brought to zero by the cooperative action of such a series of micro-rotation operations and the axial movement of the intermediate shaft gear 6. The above-described butt crush adjustment is performed for each gear element 4, 5a.

This is possible because 5b, 6a, 6b, and 8 are helical gears, and the twist directions of each gear element are different. Further, in the above example of operation, the integrated buck crush fn is caused by the first stage helical gear 6a of the intermediate shaft gear 6 and the motor output shaft 3.
Although the case where the helical gear 4 is located between the helical gear 4 and the helical gear 4 is shown as an example, accumulated backlash that occurs between the gears at any other location can be eliminated by adjusting the axial movement of the intermediate shaft gear 6. . For example, the integrated butt crush fn is the left tooth surface of the first stage helical gear 5a of the intermediate shaft gear 5 and the helical gear 4 of the motor output shaft 4, as shown in FIGS. 3(a) and 3(b). Suppose it is in between. In this case, when the intermediate shaft gear 6 is moved a distance S in the axial direction by the holding member 23, the pushing force of this axial movement is dispersed, and a part of the pushing force is as shown in FIG. 3(b). The torque is transmitted from the left tooth surface of the second stage gear 6b of the intermediate shaft gear 6 to the helical gear 8, and the helical gear 8 slightly rotates in the direction of the arrow (left rotation direction). The remaining pushing force from the axial movement is transferred from the right tooth surface of the first stage helical gear 6a of the intermediate shaft gear 6 to the right side of the helical gear 4 of the motor output shaft 3. This is transmitted to the tooth surface, and finally the first stage helical gear 5a of the intermediate shaft gear 5 and the helical gear 4 rotate slightly in a direction to eliminate backlash fn as shown by the arrow. As a result, this accumulated backlash is eliminated. Note that the frictional force between each gear is determined by the degree of movement of the intermediate shaft gear 6, so the movement of the intermediate shaft gear 6 should be prevented to ensure that the frictional force after the backlash is resolved is at a level that does not cause any problems. stop.

Figures 4(a) and (b) show the gear meshing state in which backlash has been eliminated in both the left-hand rotation torque transmission system of the electric motor and the right-hand rotation torque transmission system of the electric motor by adjusting the backlash as described above. The direction of the rotation arrow in FIG. 4(b) is, when the motor output shaft 3 is rotated clockwise, the helical gear 4 → the first stage helical gear 6a → the second stage helical gear 6b.
→Represents the rotational state in which right-handed rotation torque is output to the motor output shaft 7 via the electric motor right-handed rotation torque transmission system of the helical gear 8.

According to this embodiment, by eliminating the accumulated backlash fn in both the left and right rotational torque transmission systems of the electric motor, the electric motor 2 and the reduction gear 1 are frequently switched left and right like a power steering device. Even when used in a mechanical system, the torque transmission response between gears can be improved, and vibration noise of the speed reducer caused by backlash can be reduced. Furthermore, according to this embodiment, part crush can be adjusted by providing an adjusting means that can move one of the intermediate shaft gears in the axial direction.
The backlash adjustment mechanism and the entire structure of the reducer can be simplified, and the backlash adjustment can be easily performed.

In this embodiment, the intermediate shaft gear 6 is moved in the direction of the arrow A to adjust the back crush, but considering the relationship between the helix angles of each gear, the intermediate shaft gear 5 is moved in the direction of the arrow instead of the intermediate shaft gear 6. Even if the parts are moved axially in the opposite direction, the same parts crush adjustment as described above can be performed. Furthermore, by applying lubricating oil to the gear mechanism of the speed reducer, it is possible to improve the life of the gear mechanism.

〔Effect of the invention〕

As described above, according to the present invention, even if the gear mechanism of the reducer is a mechanism that frequently switches from left to right to rotate, backlash between the gears in both rotational directions can be eliminated by simple adjustment, and as a result, A reduction gear with excellent noise reduction and operational responsiveness can be provided.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway sectional view showing an embodiment of the present invention, FIGS. 2(a) and 3(b), and FIG. 3(a). (b) and FIGS. 4(a) and (b) are a side view and a front view of essential parts schematically showing the meshing state of each gear element in order to explain the operation of the above embodiment, and FIG. 5 is a main part front view. It is a block diagram which applied the reducer of the said Example to an electric power steering. DESCRIPTION OF SYMBOLS 1... Reduction gear, 2... Electric motor, 3... Motor output shaft, 4... First helical gear, 5, 6... Intermediate shaft gear, 5a. 6a... 1st stage helical gear, 5b, 6b... 2nd stage helical gear, 7... Reduction gear output shaft, 8... 2nd helical gear, 23... Intermediate shaft gear movement adjustment mechanism.

Claims (1)

[Claims] 1. The first part transmits the rotational output of the electric motor to the output shaft of the reducer.
A helical gear and a second helical gear are arranged on the same axis, a pair of intermediate shaft gears are arranged parallel to the axes of the first and second helical gears, and each intermediate shaft gear is arranged parallel to the axis of the first and second helical gears. The shaft gears each include a first stage helical gear for deceleration that meshes with the first helical gear, and a second stage helical gear that meshes with the second helical gear. , one intermediate shaft gear of the pair of intermediate shaft gears transmits torque during counterclockwise rotation of the first helical gear to the second helical gear, and the other intermediate shaft gear is a system for transmitting torque when the first helical gear rotates clockwise to the second helical gear, and the first,
The second helical gear and the first and second stage helical gears are set such that the helical gears have alternately different helical directions, and at least one of the pair of intermediate shaft gears is set in the axial direction. A speed reducer characterized by being provided with a mechanism for adjusting movement.