JPH02216368A - Small angle steering device - Google Patents

Abstract

PURPOSE:To make it possible to correct the steering power characteristic to the optimum by mounting to a steering power transmitting route a reaction force giving mechanism increasing rotary resistance of the steering power transmitting route in accordance with an increase of a car speed, 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 offset similarly in the major axis direction. 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. While this reaction force giving mechanism 20, by supplying oil of pressure in a level in accordance with a car speed from an input port 37 into a pressure oil chamber 52, is constituted so as to increase reaction force in accordance with the car speed.

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 wheels.

(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 the gear ratio causes the steering response to become too sensitive when the steering wheel is near neutral, causing a problem that it becomes difficult to perform corrective steering operations, especially when driving at high speeds.

The present applicant has proposed Utility Model Application No. 63-55845 as a small rudder angle steering device that can overcome these problems. By using an elliptical gear mechanism, it is possible to obtain a steering characteristic in which the gear ratio increases as the steering angle of the steering wheel increases, and the steering response becomes sensitive when the steering wheel is near neutral. This reduces the steering wheel angle necessary to fully steer the steering wheels while preventing excessive steering. 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, and can meet the above requirements with a simple configuration. there were.

(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-mentioned device exhibits a tendency for the steering force to increase as the steering angle increases due to a change in the gear ratio of the elliptical gear mechanism, and this tendency itself is desirable from the above point of view.

However, the characteristics of the steering force change with respect to the steering angle change described above cause the following problems. In other words, if the steering force at large steering angles is set lightly with emphasis on improving maneuverability when driving at low speeds, the steering force near small steering angles used when driving at high speeds becomes too light, resulting in a lack of stability. However, if the steering force around small steering angles was set to be heavy with emphasis on stability when driving at high speeds, the steering force used at large steering angles when driving at low speeds became too heavy, which resulted in a problem that actually worsened the operability. .

(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, this is achieved by installing a reaction force applying mechanism on the steering force transmission path that increases the rotational resistance of the steering force transmission path in accordance with an increase in vehicle speed.

(Function) According to the present invention, the reaction force applying mechanism that increases the rotational resistance of the steering force transmission path in accordance with an increase in vehicle speed is attached to the steering force transmission path that transmits the rotation of the steering wheel to the steering gear box. By setting this reaction force applying mechanism, it is possible to control the steering force according to changes in vehicle speed independently of the steering force change characteristics with respect to the steering angle caused by changes in the gear ratio of the elliptical gear mechanism. It becomes possible to obtain a good steering feeling in response to both changes.

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

1 to 7 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 the steering shaft l connected to the steering wheel (not shown) is connected to the 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 human power 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 the output shaft 7 is arranged at a position offset from the center of the first elliptical gear 4 in the longer diameter direction, similarly to the human power shaft 3. 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 angle of the input shaft 30 increases with an increase in the steering angle of the steering wheel, 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 and always meshes with the planetary gear 11. Further, the sun gear 12 of the planetary gear structure 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 machine M42 is accelerated and manually applied 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 9 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 the 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 input 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 human power 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.

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 with different spring constants are installed inside the tin link housing 23. It is stored in. The reaction force piston 26 is slidably provided in the spring housing 23 and is urged toward the human power shaft 3 by coil springs 24 and 25.

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 input 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 2I 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 is arranged so that the shortest diameter portion is in contact with the roller 22 when the steering wheel (not shown) is in the neutral position. Therefore, the effective radius of the portion of the cam body 21 that contacts the roller 22 increases with the rotation of the human power shaft as the steering angle increases. Note that since the maximum rotation of the input shaft 3 is set to approximately half a rotation, the effective radius of the cam body 21 does not decrease significantly when the steering angle is large.

Further, the spring retainer 51 supporting the outer end side of the coil spring 24, 25 is attached to the spring housing puffer 23.
It is arranged so that it can be slid freely inside.

A hydraulic chamber 52 is formed between the bottom of the spring housing 23 and the spring retainer 51, and hydraulic pressure is introduced from an input port 37 formed in the bottom of the spring housing 23.

FIG. 4 shows a mechanism for generating oil pressure supplied from the input port 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 port 37. The IJ leaf valve 46 is used to return a portion of the oil discharged when the flow rate of the oil pump exceeds a predetermined value to the reserve tank 41, and prevents excessive hydraulic pressure from acting on the human-powered boat 37. It has become a thing.

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, and as the rotation of the human power shaft 3 increases, the elliptical shape The gear ratio of the gear 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. 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.

Furthermore, in the reaction force applying mechanism 20, the effective radius of the portion of the cam body 21 that contacts the roller 22 increases as the human power shaft rotates, so that the springs 24 and 25 are gradually compressed accordingly.

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. 6 shows the steering force characteristics when this reaction force applying mechanism 20 is provided and when it is not provided. In FIG. 6, even when the reaction force applying 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 is generally larger, and there is a warning to the driver, and the difference in steering force between near neutral and near the maximum steering angle is also large, and careless operation can cause the steering angle to increase. You can prevent this from happening. Also, as is clear from Figure 6,
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.

Note that the steering force characteristics of 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.

Further, the characteristics shown in FIG. 6 show the characteristics in a constant vehicle speed state, and as the vehicle speed changes, the steering force level naturally changes. That is, since the hydraulic pressure applied to the human-powered boat 37 is responsive to the vehicle speed, the springs 24 and 25 are shortened as the vehicle speed increases, and the rollers 22
The force with which the vehicle presses the cam body 21 increases as the vehicle speed increases. Therefore, the rotational resistance of the human power shaft increases as the vehicle speed increases, and as shown in FIG. 7, it is possible to obtain vehicle speed-sensitive steering force characteristics in which the steering force increases as the vehicle speed increases. Therefore, when the vehicle is running at high speed, the steering force increases and stability is improved, and when the vehicle is running at low speed, the steering force is reduced and the operability is improved.

In addition, due to the shape of the cam body 21, the steering force increases as the steering angle increases, so when driving at high speeds where high oil pressure is supplied, unless the steering wheel is operated with a considerably large steering force, careless steering operations may cause the steering wheel to move. The vehicle is not steered significantly, further improving safety.

Furthermore, when the vehicle is running at low speed, almost no hydraulic pressure is supplied to the hydraulic chamber 52, but the spring retainer 51 bottoms out and the roller 22 is urged only by the urging force of the springs 24 and 25, and the shape of the cam body 21 , the characteristic of increasing the steering force in accordance with the increase in the steering angle can be set independently of the settings of the elliptical gear mechanism 2.

According to the first embodiment, by providing the reaction force applying mechanism 20 to which oil pressure responsive to the vehicle speed is supplied, it is possible to obtain desirable characteristics as a steering device in which the steering force increases as the vehicle speed increases. The steering feeling during driving becomes favorable, and sudden steering due to careless steering operation is more reliably prevented.

Since the steering force increases depending on the vehicle speed and the steering angle, the steering force at low speeds and large steering angles can be set relatively light, while the steering force at high speeds and small steering angles can be set relatively heavy. This has the effect of providing a small steering angle steering device that can achieve both operability during low-speed driving and stability during high-speed driving even if the steering force is increased depending on the steering angle.

Furthermore, 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 optimum steering angle characteristic can be set by setting the elliptic gear mechanism 2. At the same time, the steering force characteristic determined by the setting of the elliptical gear mechanism can be corrected to the optimum one by the setting of the reaction force applying mechanism 20. This effectively prevents the steering response around neutral from becoming too sensitive, and at the same time effectively prevents sudden steering due to careless steering operations, while steering the steering wheel to the maximum steering angle. This has the effect of reducing the angle and improving the operability of the steering device.

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 input to the power steering device can be almost the same as that of commonly used conventional 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, since the cam body 21 of the reaction force applying mechanism 20 is approximately heart-shaped, and the roller 22 is pressed against the shortest diameter part of the cam body when in neutral, it is easy to feel the neutral position of the steering wheel. At the same time, an automatic return function to the neutral position is achieved, which facilitates steering operation and improves stability when traveling straight.

FIG. 8 shows a second embodiment of the 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 3], 3
2 constitutes a speed increasing mechanism, and the output shaft 70
The rotation speed is increased by helical gears 31 and 32, and the rotation is manually applied to the input valve 9.

Further, a mainspring spring 35 for adjusting the steering force is provided separately from the reaction force applying mechanism. The mainspring spring 35 is configured by a mainspring spring 35 arranged around the human power shaft 3 and provided between the input shaft 3 and the casing 5. This mainspring spring 35 is elastically deformed by the rotation of the human power shaft 3, so that the input shaft 3
The biasing force increases with the rotation of the shaft 30, thereby increasing the rotation resistance of the human powered shaft 30. Therefore, the first reaction force applying mechanism 33 alone can obtain the effect of increasing the steering force in accordance with an increase in the steering angle.

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 only hydraulic pressure. For this reason, the casing 5 is provided with a plunger 36 that is slidably arranged in a direction perpendicular to the output shaft 7, and a roller 22 is attached to the tip of the plunger 36.
is rotatably supported. The hydraulic pressure supplied from a manual boat 37 provided in the casing 5 acts on the rear end of the plunger 36, and the force with which the roller 22 presses the cam body 21 changes depending on the manual hydraulic pressure. It becomes. Note that since the cam body 21 has the same shape as in the first embodiment, as long as hydraulic pressure is supplied from the human-powered 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.

Further, the hydraulic pressure supplied from the input boat 37 is supplied from the hydraulic pressure supply device shown in FIG. 4 as in the first embodiment, and the supplied hydraulic pressure increases as the vehicle speed increases. It becomes.

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

In particular, in the second reaction force applying mechanism, the hydraulic pressure input to the input 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. Become. Therefore, the rotational resistance of the input shaft increases as the vehicle speed increases, and as in the case of the first embodiment, 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, 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, the same effects as those of the first embodiment can be obtained, and the input shaft 3 and the steering output shaft 14 are arranged on the same axis as in a normal steering device. Therefore, the device of this embodiment can be installed in place of a normal steering device without modifying the vehicle body.
This 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 specifications of the vehicle.

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 steering force increases according to the vehicle speed and the steering angle, so the steering force at low speed and large steering angle increases. It is possible to set the steering force relatively light while making the steering force relatively heavy at high speed and small steering angles, and even if the steering force increases depending on the steering angle, it maintains operability at low speeds and stability at high speeds. The present invention has the effect of providing a small steering angle steering device that can achieve both safety and performance.

[Brief explanation of the drawing]

1 to 7 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 schematic configuration diagram of the hydraulic pressure supply system, FIG. 5 is a steering angle characteristic diagram, FIG. 6 is a steering force characteristic diagram with respect to steering angle, and FIG. 7 is a steering force characteristic diagram with respect to vehicle speed.
FIG. 8 is a longitudinal sectional view of an apparatus showing a second embodiment of the present invention. 2... Elliptical gear mechanism, 4... First elliptical gear 6...
2nd elliptical gear, 20.34... Reaction force applying mechanism negative ■ 2nd gear

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 small steering angle steering device, characterized in that it is equipped with a reaction force applying mechanism that increases the rotational resistance of the steering force transmission path.