JPS62255285A - Steering gear for automobile - Google Patents

Abstract

PURPOSE:To make a minimum turning radius smaller and garaging or the like performable in an easy manner, by giving braking force to rear wheels when an automobile, whose front wheels are driven at the least, turns around at a large steering angle. CONSTITUTION:At the time of running at dead slow speed, if a steering wheel is steered to the left in full, usually, respective front wheels 2 and 3 take maximum steering angles thetal and thetar, driving force T works there, whereby the turning center P0 comes to a point of intersection with a vertical line to the driving force T at each axle extension line A, B of rear wheels 4 and 5 and front-wheel turning centers C and D, thus it comes to a minimum turning radius R0. However, when the maximum steering angle and the dead slow car speed are detected at detecting elements 21 and 22, a controller 23 gives braking force F to each rear wheel via a control valve 25, a booster 24, a wire 26, an equalizer 18 and a cable 19, whereby each drive T1 of front wheels becomes equivalence to the vector composite value of original T and F, and the turning center comes to P1, while the minimum turning radius is reduced to R1 from R0. Thus, garaging and a U-turn or the like are easily performable.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a steering system that reduces the minimum turning radius of an automobile.

(Prior Art) Conventionally, automobiles have been required to have a minimum turning radius as small as possible at very low speeds for convenience when parking the vehicle in a garage or making a U-turn on the road.

In particular, the longer the wheelbase vehicle becomes, the stronger the demand becomes.One technology that meets this demand is disclosed, for example, in Japanese Unexamined Patent Publication No. 55-22561. This technology makes the ratio of the tire turning angle to the steering wheel turning angle of the vehicle variable, so that when making a small turn at low speed, the tire turning angle is determined to provide the minimum turning radius when the steering wheel is at a large turning angle. It is. However, this technique does not take measures to actively reduce the minimum turning radius itself.

(Object of the Invention) In view of the above points, the present invention provides a steering device that can make the turning radius of an automobile even smaller than that normally obtained by steering the front wheels, and improves the drivability of the automobile. The purpose is to improve.

(Structure of the Invention) As a means for achieving the above object, the present invention provides a steering system for an automobile in which at least the front wheels are driven. The present invention is characterized by comprising a braking means that applies braking force to the rear wheels when a large steering angle is detected.

The operation of the steering system of the present invention will be explained.

The principle that when a car with at least the front wheels driven tries to rotate at an extremely low speed, the center of rotation coincides with the intersection of the axle center line of the rear wheels and a line perpendicular to the driving force at the center of rotation of each front wheel (so-called Therefore, if the steering angle detection section detects a large steering angle of the front wheels and applies braking force to the rear wheels, the driving force and direction of the driving force at the front wheels will be different from the original driving force and braking force. Since the state is equivalent to vector synthesis, the intersection point, that is, the center of rotation, is moved toward the rear wheels compared to the conventional case where no braking force is applied to the rear axle. As a result, the minimum turning radius is smaller than that of conventional models.

(Example) Hereinafter, an example of the present invention will be described based on FIGS. 1 to 8.

The automobile 1 in each embodiment is a so-called front-wheel drive vehicle in which left and right front wheels 2.3 are driven.
and the main brake 6 acts on the rear wheels 4 and 5,
A parking brake 7 acts on each rear axle 4,5. The main brake 6 uses a booster 9 to increase the pressure of the foot pedal applied to the brake pedal 8 and transmits the pressure to the master cylinder 1o, and the hydraulic pressure generated in the master cylinder 10 is transmitted to the front main brake via a hydraulic line 11 via a proportioning valve 12. 13 and rear main brake 14, and acts as a braking force on the left and right front wheels 2, 3 and rear wheels 4.5. Furthermore, the parking brake 7 amplifies the manual force applied to the distal end of the parking lever 15 with the disc 16 at the proximal end, pulls the parking cable 17, and connects the two parking cables connected to it via the equalizer 18. By pulling the cable 19, braking force is applied to the left and right rear wheels 4, 5.

Steering bag of the first embodiment! ! 20, as shown in FIG.
In the automobile 1, a control valve 25 of the booster 24 is provided with a steering angle detection section 21 that detects the steering angles of the front wheels 2 and 3 and a vehicle speed detection section 22 that detects the vehicle speed of the automobile 1 separately via a controller 23. The connecting portion of the booster 24 is connected to the equalizer 18 by a control wire 26. The control valve 25 is a valve that controls activation and return of the booster 24.

As shown in FIG. 2, the operation of the steering device 20 is such that when the steering wheel (not shown) of the automobile 1 is turned all the way to the left at extremely low speeds, the front wheels 2. or, the driving force T acts in the direction of the maximum steering angle θr. The rotation center PG of the car 1 at this time is
Driving force T at the extension line of the axle center line A-B of the rear axles 4, 5 (thin solid line in the figure) and the rotation center C, D of each front wheel 2, 3
coincides with the intersection with the vertical line (double-dashed line in the figure),
The minimum turning radius is Ro (=Po D). However, at this time, the steering angle detection section 21 and the vehicle speed detection section 22 detect the maximum steering angles θl and θr, respectively, and the extremely low vehicle speed, and these detected values is sent to the controller 23.

The controller 23 compares the detected value with a preset value and sends a braking signal to the control valve 25. The control valve 25 operates the booster 24, and the booster 24 pulls the parking cable 19 via the control wire 26 and the equalizer 18.
Gives braking force F to . At this time, the driving force T1 at each front wheel 2, 3 is equivalent to the vector combination of the original driving force T and the braking force F, so the rotation center P1 of the automobile 1 is located at the axle center line A- Extension line of B and center of rotation C
, D, and the minimum rotation radius is Rs (=PtD).
In other words, by applying braking force F to the rear wheel 4.5, the center of rotation moves from po to the rear wheel side to pt, and the minimum turning radius decreases from R to R. .

As shown in FIG. 3, the steering device 27 of the second embodiment has the booster 9 of the first embodiment also have the function of the booster 24 in addition to its original function,
When applying braking force F to the vehicle, the booster 9 pulls the parking cable 19 via the brake pedal 8, control wire 26, and equalizer 18. At this time, the hydraulic pressure of the main brake 6 generated in the master cylinder 10 is
It circulates between the control valve 28 provided in the middle of the hydraulic line 11 and is prevented from flowing into the proportioning valve 12 side. However, when the brake pedal 8 is stepped on, the brake pedal detection unit 29 connected to the controller 23 sends a signal to the controller 23, and the controller 23 connects the hydraulic line 11 to the proportioning valve 12 and activates the main brake 6. The control valve 28 is controlled so as to.

As shown in FIG. 4, the steering system 30 of the third embodiment applies the braking force F in the first embodiment to the rear axle 4 or 5 on the inner wheel side of the turning of the automobile 1 (for example, when turning to the left, the left rear wheel 4 or 5 ). Therefore, the steering angle detection section 21 is designed to be able to detect left and right, and two boosters 24 are provided, and each booster 24 applies a braking force F to the corresponding rear axle 4 or 5 through a separate control wire 26. .

In this way, by applying braking force only to the rear wheel on the inner side of the turn, the minimum turning radius can be effectively reduced.

As shown in FIG. 5, the steering device 31 of the fourth embodiment has a reduction gear 3 coaxially connected to the disc 16 of the parking lever 15.
2, and the motor 33 is connected to the controller 23. When the controller 23 receives the detected values from the steering angle detection section 21 and the vehicle speed detection section 22, it rotates the motor 33 and drives the disc 16.
The parking cable 19 is pulled through the parking cable 17 and the equalizer 18 to apply braking force F to the left and right rear axles 4°5.

As shown in FIG. 6, the steering device 34 of the fifth embodiment applies the rear main brake 14 only to the rear wheel on the inner wheel side of the turn. Therefore, the steering angle detection section 21 is designed to be able to detect left and right, and the booster 9 has a control valve 2.
Control valves 35 and 3 are provided in the middle of the hydraulic line 11 and the rear main brake 14 line.
6 are respectively provided, and the downstream line of the control valve 36 of the rear main brake 14 and the control valve 35 are connected by a bypass line 37. If the brake pedal 8 is not depressed, the steering angle detection unit 2
1. Upon receiving the signals from the vehicle speed detector 22 and the brake pedal detector 29, the controller 23 controls the control valve 25 to operate the booster 9, causing the master cylinder 10 to generate hydraulic pressure and sending it to the hydraulic line 11.

The controller 23 controls the control valve 35 to change the hydraulic pressure of the hydraulic line 11 to the corresponding bypass line 37.
is sent to the line of the rear main brake 14 through the brake line, and applies braking force F to the rear wheel 4 or 5 on the inner wheel side of the turn. At this time,
Controller 23 controls control valve 36 to prevent hydraulic pressure from flowing back toward proportioning valve 12 . Note that when the brake pedal 8 is depressed, the controller 23 receives a signal from the brake pedal detection section 29.

The control valves 35 and 36 are controlled so that the main brake 6 is operated.

As shown in FIG. 7, the steering device 38 of the sixth embodiment utilizes the movement of a rack 40 driven by a steering wheel 39 in so-called rack-and-pinion steering. It gives braking force F to.

Therefore, the control rod 4 is placed in the middle of the rack 40.
1 is provided protrudingly, and the two control wires 26 are tightly attached to the control rod 41 with a certain dead zone X.
Each control wire 26 is positioned by a guide 43 attached to the rack housing 42. A steering tie rod 44 is connected to both ends of the rack 40. For example, when the steering wheel 39 is turned to the left, the rack 40 moves to the right (in the direction of the arrow in the figure), but with a normal steering angle, is this not noticeable? Due to the presence of FX, the control wire 26 is not pulled, so no braking force F is applied to the rear axles 4, 5. However, when the steering angle is large, the amount of movement of the rack 40 exceeds the dead zone X, so the control rod 41 is connected to the corresponding control wire 26 (
(lower wire in the diagram) and pull the left rear wheel 4 on the inner turning axis side.
Gives braking force F to .

As shown in FIG. 8, the steering device 45 of the seventh embodiment uses so-called power steering hydraulic pressure to apply a braking force F to the rear wheel 4 or 5 on the inner wheel side of the turn. Therefore, a piston 47 is slidably inserted into a hydraulic cylinder 46 connected to the steering wheel 39, and steering tie rods are connected to both ends of the piston rod of the piston 47 (not shown). , both sides of the piston 47 are connected to a control valve 49 through two hydraulic lines 48 , a power steering hydraulic power source 50 is connected to the control valve 49 , and two hydraulic cylinders 5 are connected through two hydraulic lines 51 .
Each hydraulic cylinder 52 has a piston 53 slidably inserted therein, and is connected to the downstream line of the control valve 36 of the rear main brake 14 by two hydraulic lines 54. The steering angle detection section 21 is capable of detecting left and right. When the brake pedal 8 is not depressed, for example, when the steering wheel 39 is turned all the way to the left at an extremely low speed, the steering angle detection section 21 and the vehicle speed detection section 22
The controller 23 receives the signal from the brake pedal detector 29 and controls the control valve 49,
Hydraulic pressure from the hydraulic source 50 is supplied into the hydraulic cylinder 46 via one side of the hydraulic line 48 (lower side in the figure), and the piston 47
Move to the right (in the direction of the arrow in the figure). piston 47
The hydraulic pressure on the right side of is supplied to the corresponding hydraulic cylinder 52 (lower side in the figure) via the other side of the hydraulic line 48 and the control valve 49, and pushes the piston 53.
The main brake hydraulic pressure on the opposite side is sent to one line of the rear main brake 14 via the hydraulic line 54, and applies braking force F to the left rear wheel 4 on the inner wheel side of the turn. At this time, the controller 23 controls the hydraulic pressure to the proportioning valve 1.
The control valve 36 is controlled so that the flow does not flow back toward the second direction. Note that when the brake pedal 8 is depressed, the controller 23 receives a signal from the brake pedal detection section 29 and controls the control valves 36 and 49 so that the main brake 6 is operated.

Although the automobile 1 in each of the above embodiments is a front-wheel drive vehicle, it is not necessarily limited to a front-wheel drive vehicle.
The vehicle may be a so-called four-wheel drive vehicle as long as at least the front wheels are driven.

(Effects of the Invention) Since the present invention is configured as described above, when an automobile in which at least the front axle is driven turns at a large steering angle, braking force is applied to the rear axle to reduce the minimum turning radius. Can be done. Therefore, it becomes extremely easy for the automobile to turn around in a small radius.

[Brief explanation of drawings]

FIG. 1 is a system diagram of the first embodiment of the present invention, FIG. 2 is an explanatory diagram showing the operating state of the present invention, and FIGS. 3 to 8 are diagrams of the second to seventh embodiments of the present invention. It is a system diagram. 1...Car, 2...Left front wheel, 3...
...Right front axle, 4...Left rear wheel, 5...
・Right rear wheel, 20... Steering device (first embodiment),
21... Rudder angle detection section, 27... Steering device! (Second embodiment), 30... Steering device (Third embodiment)
Example), 31...Steering device! (Fourth example)
, 34... Steering device (fifth embodiment), 38...
... Steering device (sixth embodiment), 45... Steering device (seventh embodiment), F... Braking force, R1.
...Minimum turning radius, θ ...Maximum steering angle (
left front wheel), θr... Maximum steering angle (right front axis).

Claims (2)

[Claims] (1) In a steering system for an automobile in which at least the front wheels are driven, there is a steering angle detection section that detects the steering angle of the front wheels, and when this steering angle detection section detects a large steering angle of the front wheels, it applies braking force to the rear wheels. A steering device for an automobile, characterized in that it is equipped with a braking means that provides braking. (2) The braking means is a means for applying a braking force only to the inner rear wheels when the steering angle detection section detects a large steering angle of the front wheels. Automobile steering system.