JPH02216367A - Small angle steering device - Google Patents

Abstract

PURPOSE:To facilitate positioning of a neutral position by mounting a reaction force giving mechanism, which provides a cam unit and a pressing piece of predetermined shape increasing rotary resistance of a steering power transmitting route in accordance with an increase of a steering angle, to said route, in the case of a device interposing an elliptic gear mechanism in the steering power transmitting route. CONSTITUTION:An upper end of an input shaft 3 of an elliptic gear mechanism 2 is connected by serration to a lower end of a steering shaft 1. This elliptic gear mechanism 2 is constituted by housing in a casing 5 the first elliptic gear 4 fixing the input shaft 3 in a position offset in a major axis direction and the second elliptic gear 6 fixing an output shaft 7 in a position similarly offset in the major axis direction. While the first elliptic gear 4 integrally forms a cam unit 21 adapting to its periphery a roller 22 pressed by receiving tension of coil springs 24, 25 and actuated functioning as a reaction force giving mechanism 20. And this cam unit 21 is formed in its effective radius so as to decrease to the minimum with a steering wheel in its neutral condition while to increase in accordance with an increase of a steering angle.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement of a small steering angle steering device that reduces the steering wheel angle required to fully steer the steering wheel.

(Prior Art) Steering devices commonly used for automobiles require the steering wheel to be rotated more than once before the steering wheel is steered to the maximum steering angle, which is useful for people who frequently drive, such as professional drivers. For those who do this, operating the steering wheel is one of the causes of fatigue.

For this reason, various types of small steering angle steering devices have been proposed to obtain a large steering wheel steering angle with a small number of steering wheel operations. In order to simply meet these demands, the steering gear ratio can be set high as in a four mirror car. However, simply increasing or decreasing the gear ratio causes a problem in that the steering response becomes too sensitive when the steering wheel is near neutral, making it difficult to perform corrective steering operations, especially when driving at high speed.

The present applicant has proposed Utility Model Application No. 63-55845 as a small steering angle steering device that can overcome these problems. This uses an elliptical gear mechanism to obtain a steering characteristic in which the gear ratio increases as the steering angle of the steering wheel increases.
This reduces the steering angle required to fully steer the steered wheels while preventing the steering response from becoming too sensitive near the neutral position of the steering wheel. More specifically, an elliptical gear mechanism is interposed in the steering force transmission path that transmits the rotation of the steering wheel to the steering gear box, and the shortest diameter of the first elliptical gear of the elliptical gear mechanism connected to the steering wheel side. and the longest diameter part of the second elliptical gear connected to the steering gear box are configured so that they mesh with each other when the steering wheel is in a neutral state,
The above requirements could be met with a simple configuration.

(Problem to be Solved by the Invention) By the way, in such a small steering angle steering device, since a large steering wheel steering angle can be obtained with a small steering wheel steering angle, it is difficult for people who are accustomed to ordinary steering devices to It is desirable to increase the steering force in accordance with the increase in the steering angle so that the steering angle does not suddenly increase even if the steering angle is carelessly operated.

The above device shows a tendency for the steering force to increase as the steering angle increases due to changes in the gear ratio of the elliptical gear mechanism, but the steering force characteristics are uniquely determined by setting the gear ratio of the elliptical gear mechanism. There is a problem in that it is difficult to obtain good steering force characteristics with respect to the steering angle while setting the optimum gear ratio.

On the other hand, when reducing the steering angle as described above, the response especially near the neutral point of the steering wheel becomes slow, so there is the inconvenience that it is difficult to feel the neutral position when steering back. Ta.

(Means for Solving the Problems) The present invention solves the above problems by interposing an elliptical gear mechanism in the steering force transmission path that transmits the rotation of the steering wheel to the steering gear box. The shortest diameter part of the first elliptical gear connected to the wheel side and the longest diameter part of the second elliptical gear connected to the steering gear box are configured to mesh with each other when the steering wheel is in a neutral state. In the steering angle steering device, a cam body is provided in the steering force transmission path and rotates together with the elliptical gear mechanism, and a pusher is biased by a biasing means and pressed against a cam surface of the cam body. A force applying mechanism is provided, and the effective radius of the lip portion of the cam body that comes into contact with the suppressor is formed to be minimum when the steering wheel is in a neutral state and to increase as the steering angle increases. This is achieved by a small rudder angle steering device featuring:

(Function) According to the present invention, the reaction force applying mechanism is provided, which includes a cam body provided in the steering force transmission path and a pusher that is urged by the urging means and pressed against the cam body. By setting the rotational resistance characteristics generated by the force applying mechanism, it is possible to set the steering force relative to the steering angle independently of the gear ratio setting of the elliptical gear mechanism, making it possible to obtain a good steering feeling. Become.

In particular, since the cam body is arranged so that the effective radius of the part that contacts the pusher increases as the steering angle increases, the reaction force applying mechanism increases the rotational resistance of the steering force transmission path as the steering angle increases. As a result, the difference between the steering force at a large steering angle and the steering force at a small steering angle becomes even larger, and it is more effectively prevented that an inadvertent operation causes sudden steering.

In addition, the effective radius of the part of the cam body that comes into contact with the pusher is minimized when the steering wheel is in the neutral state, so the neutral position of the steering wheel is positioned and is easy for the driver to experience. Become something.

(Example) Hereinafter, an example of the present invention will be described in detail based on the accompanying drawings.

1 to 5 show a first embodiment of the present invention.

FIG. 1 shows a longitudinal sectional view of the main part of the device. In FIG. 1, the lower end of a steering shaft 1 connected to a steering wheel (not shown) is connected to an elliptical gear mechanism 2.
Serrations are connected to the upper end of the input shaft 3 of the input shaft 3. The first elliptical gear 4 of the elliptical gear mechanism 2 is fixed and prevented from rotating on the outer periphery of the input shaft 3 inside the casing 5, and the human power shaft 3 is offset from the center of the first elliptical gear 4 in the major diameter direction. It is placed in the same position. The second elliptical gear 6 that meshes with the first elliptical gear 4 within the casing 5 is fixed and prevented from rotating around the outer periphery of an output shaft 7 disposed within the casing 5 in parallel to the input shaft 3.

Note that, like the input shaft 3, the output shaft 7 is arranged at a position offset from the center of the first elliptical gear 4 in the major diameter direction. Further, as shown in FIG. 2, in the elliptical gear mechanism 2, the shortest diameter part of the first elliptical gear 4 and the longest diameter part of the second elliptical gear 6 are mutually connected when the steering wheel (not shown) is in the neutral position. It is designed to mesh with the Therefore, as the rotation of the input shaft 3 increases as the steering angle of the steering wheel increases, the gear ratio of the elliptical gear mechanism 2 increases. In this embodiment, the maximum steering angle of the steering wheel is set to about half a turn, so the gear ratio does not become low when the steering angle is large.

The output shaft 7 of the elliptical gear mechanism 2 is connected to an inner valve 9 of a power steering device via a planetary gear mechanism 8, as shown in FIG. That is, a planetary gear carrier 10 for the planetary gear mechanism 8 is integrally formed at the lower end of the output shaft 7.
A plurality of planetary gears 11 are rotatably supported. The ring gear 12 of the planetary gear mechanism 8 is connected to the casing 5
It is fixed to the planetary gear 11 and always meshes with the planetary gear 11. Further, the sun gear 12 of the planetary gear mechanism 8 is fixed to the outer periphery of the upper end of the inner valve 9, and the planetary gear 11
are always engaged.

This planetary gear mechanism 8 constitutes a speed increasing mechanism that speeds up the rotation of the output shaft 7 and transmits it to the inner valve shaft 9. That is, in addition to the revolution component of the planetary gear 11, the rotation component is transmitted to the sun gear 12, thereby increasing the speed of the sun gear 12.

Therefore, the steering angle characteristic set by the elliptical gear mechanism 2 is accelerated and input to the power steering mechanism.

Moreover, the above-mentioned inner valve 9 constitutes a well-known rotary valve together with an outer valve 13 arranged on the outer circumferential side. A steering output shaft 14 connected to the lower end of the outer valve 13 is connected to the inner valve 8 via a torsion bar 15. A pinion gear 16 provided on the lower outer periphery of the steering output shaft 14 is provided to mesh with a rack gear 18 provided on a steering rod 17, and constitutes a steering gear box 19. Note that the configuration of the power steering device and the steering gear box 19 including the inner valve 9 and below are all well-known, and further detailed explanation will be omitted.

Here, the reaction force applying mechanism 20 provided on the human power shaft 3 will be explained. The cam body 21 is formed integrally with the first elliptical gear 4 , is disposed below the first elliptical gear 4 , and rotates together with the input shaft 3 . A roller 22 biased by a spring force is pressed against a cam surface formed on the outer periphery of the cam body 21, and this roller 22 forms a presser.

That is, a cylindrical spring housing 23 is provided in the casing 5 with its axis oriented in a direction perpendicular to the axis of the input shaft, and two coil springs 24 and 25 having different spring constants are installed in the spring housing 23. It is stored. The reaction force piston 26 is slidably provided in the spring housing 23, and is attached to the coil springs 2.4. ．． 25, it is biased toward the human power shaft 3 side.

A roller support plate 27 integrally formed with the reaction force piston 26 is arranged to protrude from the inner end of the spring housing 23, and has a support shaft 28 arranged parallel to the human power shaft 3 at its tip. .

A roller 22 made of resin is rotatably supported by this support shaft 28, and is pressed against the cam body 21 by urging force from springs 24 and 25. Further, the cam body 21 is formed in a substantially heart shape as shown in FIG. 3, and the axial center is offset toward the concave portion side of the heart-shaped cam surface. The cam body 21 is arranged such that the concave portion, which is the shortest diameter portion of the heart-shaped cam surface, comes into contact with the roller 22 when the steering wheel (not shown) is in the neutral position. Therefore, the roller 2 of the cam body 21
The effective radius of the portion that contacts 2 increases as the human power shaft rotates as the steering angle increases. Note that, since the maximum rotation of the human power shaft 3 is set to about half a rotation, the effective radius of the cam body 21 does not decrease significantly when the steering angle is large.

Next, the operation of this embodiment will be explained.

Steering human power from the steering wheel is transmitted to the planetary gear mechanism 8 via the human power shaft 3, the first elliptical gear 4, the second elliptical gear 6, and the output shaft 7, and is accelerated by the planetary gear mechanism 8 and sent to the steering gear box. 19. In the elliptical gear mechanism 2, the shortest diameter part of the first elliptical gear 4 and the longest diameter part of the second elliptical gear 6 mesh with each other, so that as the rotation of the input shaft 3 increases, the elliptical gear The gear ratio of the mechanism 2 is increased. Therefore, as can be easily understood from the steering angle characteristics of this embodiment shown in FIG. However, as the steering wheel angle increases, the response of the steered wheels becomes quicker. and,
By setting such steering angle characteristics, it is possible to significantly reduce the maximum steering angle of the steering wheel to about half a turn.

In addition, in the reaction force applying mechanism 20, since the effective radius of the portion of the cam body 21 that contacts the roller 22 increases with the rotation of the input shaft, the spring 24, 25
will be gradually reduced.

Therefore, the biasing force of the springs 24 and 25 acting on the roller 22 via the reaction force piston is
1) increases as the input shaft rotates, and the pressing force of the roller 22 on the cam body 21 increases as the input shaft rotates. As a result, the rotational resistance of the human power shaft 3 increases as the steering angle increases, and the steering force for operating the steering wheel further increases as the steering angle increases.

FIG. 5 shows the steering force characteristics when this reaction force applying mechanism 20 is provided and when it is not provided. In FIG. 5, even when the reaction force imparting mechanism 20 is not provided, the steering force increases as the steering angle increases, which is a characteristic obtained by changing the gear ratio of the elliptical gear mechanism. In this case, the steering force will be larger overall, which will alert the driver, and the difference in steering force between near neutral and near the maximum steering angle will also be larger, preventing the steering angle from increasing due to careless operation. You can prevent it from being put away. Further, as is clear from FIG. 5, when the steering wheel is turned back, the reaction force applying mechanism 20 acts in a direction to reduce the steering force, so that the steering wheel is turned back easily.

In addition, the cam body 21 has a concave portion that is the shortest diameter portion of the heart-shaped cam surface when the steering wheel is in the neutral state.
2, the neutral position of the steering wheel is determined, making it easier for the driver to feel the neutral position.

Note that the steering force characteristics by the reaction force applying mechanism 20 shown in FIG. The steering force characteristics can be changed in various ways, such as by increasing the difference in steering force or increasing the rising steering force from the neutral position.

According to the first embodiment, by providing the reaction force applying mechanism 20, the steering force characteristic can be set independently of the steering force characteristic obtained by the elliptical gear mechanism 2, and the setting of the elliptical gear mechanism 2. This provides an effect that the steering force characteristic can be corrected to the optimum one by setting the reaction force applying mechanism 20 while obtaining the optimum steering angle characteristic. And with this,
This reduces the steering wheel steering angle up to the maximum steering angle, thereby improving the operability of the steering system, while preventing the steering response from becoming too sensitive near neutral and also preventing sudden steering due to careless steering operations. It has the effect of improving

In addition, the output of the elliptical gear mechanism 2 is increased in speed by the planetary gear mechanism 8 and inputted manually to the power steering device.
Even if the maximum steering angle of the steering wheel is reduced, the maximum rotation angle manually applied to the power steering device can be made almost the same as that of commonly used steering devices, and the conventional power steering device and steering gear box can be used as is. It can be repurposed. Therefore, there is an advantage that a small steering angle device with power steering can be obtained with a simple configuration and at low cost.

Furthermore, the action of positioning the neutral position by the reaction force applying mechanism 20 makes it easier to experience the neutral position of the steering wheel, and at the same time, an automatic return function to the neutral position is also achieved, which makes steering operations such as when turning back, etc. easier, and This has the effect of improving stability when driving straight.

6 to 8 show a second embodiment of the present invention.

In the second embodiment, members that are substantially the same as those in the first embodiment are given the same reference numerals, and detailed explanation thereof will be omitted.

In the second embodiment, the human power axis 3 is different from the first embodiment.
The positions of the output shaft 7 and the output shaft 7 are reversed, and the human power shaft 3 is arranged coaxially with the steering output shaft 14. For this reason,
In place of the planetary gear mechanism 8 of the first embodiment, a large diameter helical gear 31 coupled to the input shaft and a small diameter helical gear 32 coupled to the input valve 9 are used. In this embodiment, these helical gears 31, 32
constitutes a speed increasing mechanism, and the rotation of the output shaft 7 is increased in speed by helical gears 31 and 32 and input to the input valve 9.

Further, a spiral spring 35 for adjusting the steering force is provided separately from the reaction force applying mechanism. This mainspring spring 35 is arranged around the human-powered shaft 3 and is provided between the human-powered shaft 3 and the casing 5, and is elastically deformed by the rotation of the input shaft 3, thereby exerting a biasing force as the input shaft 3 rotates. This increases the rotational resistance of the input shaft 3. Therefore, the mainspring spring 35 alone can provide substantially the same effect as the reaction force applying mechanism 33 of the first embodiment.

In the reaction force applying mechanism 34, a cam body 21 having the same shape as in the first embodiment is fixed to the output shaft 7, and a roller 22 is in pressure contact with this cam body 21. A major difference from the reaction force applying mechanism 20 of the first embodiment is that the force acting on the roller 22 pressed by the cam body 21 is not the urging force of a spring but a hydraulic force. For this reason, the casing 5 is provided with a plunger 36 that is slidably disposed in a direction orthogonal to the output shaft 7, and the roller 22 is rotatably supported at the tip of the plunger 36. And the human-powered boat 3 provided in the casing 5
The hydraulic pressure supplied from 7 acts on the rear end of the plunger 36, and the input hydraulic pressure causes the roller 2 to move.
2 changes the force with which it presses the cam body 21. Note that since the cam body 21 has the same shape as in the first embodiment, as long as oil pressure is supplied from the input boat 37, the rudder angle will not increase as in the first embodiment. There is no change in the fact that it also exerts the effect of increasing the steering force.

FIG. 7 shows a mechanism for generating hydraulic pressure supplied from the human-powered boat 37. An oil pump 42 that takes in and discharges oil stored in a reserve tank 41 is rotationally driven by a speedometer driven gear provided on a transmission output shaft. Therefore, the oil pump 42 rotates at a rotational speed corresponding to the vehicle speed, and the discharge flow rate increases as the vehicle speed increases. A discharge port of the oil pump 42 is connected to the human-powered boat 37 via an oil path 43.

An oil passage 44 connected to the reserve tank 41 is connected to the oil passage 43, and the oil passage 44 is provided with a throttle 45. Therefore, due to the flow resistance generated by the throttle 45, hydraulic pressure is generated upstream of the throttle 45 according to the flow rate, and since the oil pump 42 discharges oil at a flow rate corresponding to the vehicle speed, this hydraulic pressure is proportional to the vehicle speed. It will rise. Therefore, hydraulic pressure responsive to vehicle speed acts on the input boat 37. In addition, the relief valve 46
is for returning a part of the oil discharged to the reserve tank 41 when the flow rate of the oil pump exceeds a predetermined value, and prevents excessive hydraulic pressure from acting on the input boat 37.

Here, the operation of the second embodiment will be explained.

In particular, in the reaction force applying mechanism 34, the hydraulic pressure applied to the human-powered boat 37 is sensitive to the vehicle speed, so the force with which the roller 22 presses the cam body 21 increases as the vehicle speed increases. . Therefore, the rotational resistance of the input shaft increases as the vehicle speed increases, and as shown in FIG. 8, it is possible to obtain vehicle speed-sensitive steering force characteristics in which the steering force increases as the vehicle speed increases. Furthermore, due to the shape of the cam body 21, the steering force increases as the steering angle increases, as in the case of the first embodiment, so when driving at high speeds with high oil pressure supplied, unless the steering wheel is operated with a considerably large steering force. The steering wheels are not steered significantly due to careless steering operations, and safety is further improved. Furthermore, the shape of the cam body 21 naturally provides a positioning function for the neutral position, and the same effects as in the first embodiment can be obtained.

Note that when the vehicle is running at low speed, the steering force is hardly controlled by the reaction force applying mechanism 34, but the mainspring spring 3
5, it is possible to set a characteristic of increasing the steering force in accordance with an increase in the steering angle independently of the setting of the elliptical gear mechanism 2.

According to the second embodiment, in addition to obtaining the same effects as the first embodiment, it is also possible to obtain favorable characteristics as a steering device in which the steering force increases as the vehicle speed increases. The ring becomes suitable, and there is an effect that sudden steering due to careless steering operation is more reliably prevented.

Furthermore, like a normal steering device, the human power shaft 3 and the steering output shaft 14 are arranged on the same axis, so the device of this embodiment can be used in place of a normal steering device without modifying the vehicle body. It has the advantage of being easy to install on a vehicle and having a wide range of applications, such as when using a normal type steering device and a small steering angle type steering device depending on the vehicle specifications.

Note that also in the first embodiment, the spring housing 2
By forming a hydraulic chamber between the bottom of the spring retainer 51 and the spring retainer 51 and introducing hydraulic pressure responsive to vehicle speed, vehicle speed sensitive characteristics similar to those of the second embodiment can be obtained.

Furthermore, it goes without saying that the present invention is not limited to the above-mentioned embodiments, and that various other modifications are possible.

(Effects of the Invention) As described above in detail with the embodiments, according to the present invention, the reaction force applying mechanism sets the steering force characteristic independently of the steering force characteristic obtained by the elliptical gear mechanism. By setting the elliptical gear mechanism, it is possible to obtain the optimum steering angle characteristics, while by setting the reaction force applying mechanism, it is possible to correct the steering force characteristics to the optimum one, and at the same time, it also positions the steering wheel in its neutral position. It has the effect that it can.

[Brief explanation of the drawing]

1 to 5 show a first embodiment of the present invention, in which FIG. 1 is a longitudinal sectional view of the device, FIG. 2 is a plan view of the elliptical gear mechanism, and FIG. 3 is a plan view of the reaction force applying mechanism. , FIG. 4 is a steering angle characteristic diagram, FIG. 5 is a steering force characteristic diagram, and FIGS. 6 to 8 show a second embodiment of the present invention. FIG. 6 is a longitudinal sectional view of the device, and FIG. 8 is a schematic configuration diagram of the hydraulic pressure supply system, and FIG. 8 is a diagram showing steering force characteristics with respect to vehicle speed. 2... Elliptical gear mechanism, 4... First elliptical gear 6,...
・No. 2 elliptical gear, 20.34... Reaction force applying mechanism 21
..., 'Fum body, 22...Roller Applicant Mitsubishi Motors Corporation Figure Figure ζ Figure 30 60 90 120 +50 Steering Wheel JI4? kt angle (deg) negative S times wa figure cars

Claims (1)

[Claims] An elliptical gear mechanism is interposed in the steering force transmission path that transmits the rotation of the steering wheel to the steering gear box, and the elliptical gear mechanism connects the shortest diameter part of the first elliptical gear connected to the steering wheel side and the steering gear box. In the small steering angle steering device, the longest diameter part of the second elliptical gear connected to the steering wheel is configured to mesh with each other when the steering wheel is in a neutral state. A reaction force applying mechanism is provided, which includes a cam body that rotates together with the cam body, and a pusher that is biased by a biasing means and pressed against the cam surface of the cam body. A small steering angle steering device characterized in that the radius is formed to be minimum when the steering wheel is in a neutral state and to increase as the steering angle increases.