JPS6237280A - Four-wheel steering device for vehicle - Google Patents

Abstract

PURPOSE:To compact structure, by a method wherein a power cylinder is formed integrally with the containing casing of a control device adapted to control a rear wheel steering rod through a power steering device. CONSTITUTION:A hydraulic control mechanism D, adapted to control a power cylinder 12, is contained in a containing casing 8b, formed integrally with a cylindrical casing 8a for containing a rear wheel steering rod 9, together with a control mechanism C, and the hydraulic control mechanism D includes a spool valve 25 adapted to switch an oil passage. The spool valve 25 is slidably placed in a valve housing 27 secured to the rear wheel steering rod 9 through a coupling part 26. The spool valve 25 is situated on the extension of a control rod 15 extended from the control mechanism C.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a four-wheel steering device for a vehicle such as an automobile, which is configured to steer both front wheels and rear wheels by operating a steering wheel.

(Prior art) Conventionally, steering devices for four-wheeled vehicles such as automobiles have been used to steer only the front wheels, but recently, from the perspective of improving the maneuverability and running stability of the vehicle, steering devices have been designed to steer not only the front wheels but also the front wheels. A four-wheel steering device that also steers the rear wheels has been proposed.

In the case of such a four-wheel steering device, the steering torque of the steering wheel is larger than that of a vehicle that steers only the front wheels. It is necessary to install a power steering device at the rear of the vehicle body to assist in steering.

However, in such conventional devices, the rear wheel steering rod, the power cylinder of the power steering device, the oil path switching pulp, etc. are usually housed in separate casings, so the entire rear wheel steering mechanism is The structure of the vehicle is complicated, and there are problems in that it is difficult to mount these components at the rear of the vehicle body.

(Objective of the Invention) The present invention has been made in view of the above circumstances, and an object thereof is to provide a four-wheel steering device for a vehicle that is small and has a simple structure and can be easily mounted on a vehicle body. That is.

(Structure of the Invention) A four-wheel steering device for a vehicle according to the present invention includes a rear wheel steering rod that is assisted by a power steering device and is provided so as to penetrate through a power cylinder of the power steering device, and the rear wheel steering rod is provided with a rear wheel steering rod that is assisted by a power steering device. A control mechanism is provided for controlling the operation of the power cylinder in response to rear wheel steering input related to steering wheel operation, and a housing casing for the control mechanism is integrally provided with the power cylinder section. That is.

(Effects of the Invention) According to the present invention, the power cylinder of the power steering device for assisting the operation of the rear wheel steering rod and the control device for controlling the rear wheel steering rod via the power steering device are housed. Since it is integrated with the casing, the overall structure is simple and compact, and it is easier to mount it on a vehicle.

(Example) Examples of the present invention will be described in detail below.
Let us briefly explain this with reference to the figure.

In FIG. 1, a front wheel steering device A for steering left and right front wheels IL and IR includes a steering wheel 2, a rack and pinion mechanism 3 that converts the rotational motion of the wheel 2 into linear reciprocating motion, and A front wheel steering rod 4 is provided with a mechanism 3, and tie rods 5L are provided at both left and right ends of this mouth and door 4, respectively.

Left and right knuckle arms 6L connected via 5R.

It is composed of 6R.

On the other hand, a rear wheel steering device B for steering the left and right rear wheels 7L and 7R is held in a cylindrical casing 8a that constitutes a part of the housing 8 so as to be slidable in the left-right direction (vehicle width direction). A rear wheel steering rod 9 and tie rods 10 L are provided at both left and right ends of this rod 9, respectively.

Left and right knuckle arms 11L connected via 10R
, IIR, and the rear wheels 7L and 7R are steered by the movement of the rear wheel Jffi steering rod 9 in the axial direction. Further, a power steering device for assisting the movement of the rod 9 is integrally attached to the rear wheel steering rod 9, so that the port 9 is connected to a power cylinder 12 formed integrally with the casing 8a. A piston 13 that penetrates through the cylinder 12 and partitions the inside of the cylinder 12 into left and right hydraulic chambers 12a and 12b is fixed to the pressure throat 9. C is a control mechanism for controlling the rear wheel steering rod 9, and is equipped with an input shaft 14 and a control rod 15 as an output shaft, and an example of its configuration will be described later; The second rack and pinion mechanism 16 converts the linear reciprocating motion of the rod 4 in response to the raking of the steering wheel 2 into a rotational motion, and this rotational motion is controlled via the universal joint 17, 18 and the connecting rod 19. The signal is transmitted to the input shaft 14 of the mechanism C. On the other hand, a control rod 15 serving as an output shaft is provided so as to move in parallel to the rear wheel steering rod 9. In addition, this control mechanism C has a steering ratio (rear wheel steering angle θa/front wheel steering angle θa) depending on the vehicle speed.
A pulse motor 21 is connected to the pulse motor 21 for changing the rotation direction and amount of rotation of the motor 21, which is controlled by a control circuit 23 which is given an output corresponding to the vehicle speed detected by the vehicle speed sensor 22. controlled accordingly. Reference numeral 24 denotes a steering sensor mounted above the housing 8, and the output of this sensor 24 is given to a control circuit 23 to feedback control the motor 21.

A hydraulic control mechanism for controlling the power cylinder 12 is housed together with a control mechanism C in a housing casing 8b that is integrally formed with a cylindrical casing 8a that houses the rear wheel steering rod 9. , has a spool valve 25 for switching the oil path. This spool valve 25 is slidably provided within a valve housing 27 fixed to the rear wheel steering rod 9 via a connecting portion 26 . Further, this spool valve 25 is provided on an extension of the control rod 15 led out from the control mechanism C,
It is provided so as to be movable parallel to the rear wheel steering rod 9, that is, in the vehicle width direction. and the valve housing 27
In order to supply oil to the oil pressure chambers 12a and 12b of the power cylinder 12, a plurality of oil passages are provided inside each of the housing 8a, the one-wheel steering rod 9, and the connecting portion 26, and communicate with each other as described below. It is formed through relationships. That is, the oil in the oil tank 31 that is pumped by the oil pump 30 enters the oil path 33 in the housing 8a from the oil path 32, and further flows into the cylindrical casing 8a.
An oil passage 3 within the rear wheel steering rod 9 slidably supported within the rear wheel steering rod 9.
4 and an oil passage 35 in the connecting portion 26 to an oil chamber 36 in the valve housing 27 . Further, the hydraulic chambers 12a and 12b of the power cylinder 12 are connected to oil passages 37a and 37b in the rear wheel steering rod 9 and an oil passage 38a in the connecting portion 26.
, 38b to the oil chamber 36, and the oil in the oil chamber 36 is connected to the oil passage 39 in the connecting portion 26, the oil passage 40 in the rear rudder rod 9, and the oil passage in the casing 8a. 41 and returns into the oil tank 31 from an oil path 42. With this configuration, the rear wheel steering port 9 is connected to the control rod 15 which is the output shaft of the control opening groove C.
It moves from side to side within the casing 8a in response to the movement in the left and right direction. In addition, 42 is the rear wheel steering port 7 and 9.
This is a return spring mounted between the casing 8a and the casing 8a in order to return the casing 8a to the neutral position. Further, an oil pan 43 is attached below the storage casing 8b that houses the control mechanism C and the hydraulic side '4Hil', and this oil pan 43 is filled with oil to lubricate each mechanism part. It is configured.

Next, the configuration of each part in the embodiment of the present invention will be explained in more detail. FIG. 2 shows a rear wheel steering rod 9, a power cylinder 12, and
This is a diagram showing the control mechanism C and the hydraulic control mechanism, with the right half shown in FIG. 2A and the left half shown in FIG. 2B. Further, FIGS. 3 and 4 are cross-sectional views taken along the line ■-■ and the line ■-IV in FIG. 2B, respectively.

First, in FIG. 2A, the power cylinder 12, spool valve 25, and
Details of the valve housing 27 and each oil passage are shown, and the rear wheel steering rod 9 is divided into two parts 9a and 9b, left and right, in order to facilitate the formation of oil passages inside the rod.
These two rod portions 9a and 9b are integrally connected by being screwed into the cylindrical body 20 from the left and right sides. This cylindrical body 20 is controlled by the above-mentioned hydraulic control a.
It is constructed integrally with the +KD valve housing 27 and connecting portion 26. The end surfaces of the rod portions 9a and 9b do not come into contact with each other in the cylindrical body 20 (they face each other with a predetermined gap apart, and the rod portions 9a and 9b
A chamber 28 is formed between the O-ring and the inner circumferential surface of the cylindrical body 20 by attaching O-rings to the outer circumferential surfaces near the end faces of a and 9b.

The left rod portion 9a has an oil passage 37a in FIG.
, 37b, two passages 46, 47 are provided extending along the axis from the end face facing the chamber 28 to the hydraulic chambers 12a, 12b of the power cylinder 12. The passages 46, 47 communicate with the hydraulic chambers 12a, 12b through holes 48, 49 that are perpendicular to the axis. Also, only the passage 46 communicates with the chamber 28, but the passage 47 that communicates with the hydraulic chamber 12b has
In order to isolate this passage 47 from the chamber 28, a spherical stopper 29 is fitted from the end face side of the opening/7 door portion 9a. Similarly, the right rod portion b is also provided with passages 51 and 52 extending to the right from the end surface leading into the chamber 28, respectively, to form part of the oil passages 34 and 40 in FIG. However, both passages 51, 52 are closed at their ends by plugs 29 to isolate them from the chamber 28.

On the other hand, a cylindrical body 20 connecting the rod portions 9a and 9b
The valve housing 2 is inserted into the inner peripheral surface of the valve housing 2 through the connecting portion 26.
4 oil passages 38b, 38a, which communicate with the oil chamber 36 in 7.
35 and 39 are opened in this order (see Fig. 1), and among them, the oil passage 38a is opened so as to communicate with the chamber 28, so that the oil pressure chamber 12a is connected to the hole 48, the passage 46, and the chamber 28. It communicates with the oil chamber 36 in the valve housing 27 through an oil passage 37a constituted by 21H and an oil passage 38a. Further, an annular chamber 52 is formed by a groove and an O-ring on the outer peripheral surface of the left rod portion 9a at a position facing the oil passage 38b, and a hole is formed in the rod portion 9a to communicate this chamber 53 and the passage 47. As a result, the hydraulic chamber 12b communicates with the oil chamber 36 in the valve housing 27 through the oil passage 37b and the oil passage 38b, which are constituted by the hole 49, the passage 47, and the annular chamber 52. Aisle 51.5
There is also an oil passage 35 in the right rod portion 9b where 2 is provided.
．． Two annular chambers 53 and 54 are formed at a position opposite to the chamber 53 and the passage 51, and the chamber 54 and the passage 52.
are in communication with each other through holes drilled in the rod portion 9b. The passages 51.52 are connected to these passages 51.52.
A hole 55.5 drilled in the rod part b at the right end of the
6 communicate with the outer circumferential surface of the rod portion 9b, while oil passages 33 provided in the cylindrical casing 8a
．． The openings 57 and 58 on the inner circumferential surface of the casing 8a of 41 extend in the axial direction of the rod portion 9b, so that the openings 57 and 58 of the casing 8a extend in the axial direction of the rod portion 9b.
It is considered that the oil passage 33 inside the casing 8a always communicates with the passage 51, and the oil passage 41 inside the casing 8a always communicates with the passage 52. With such a configuration, the oil pump 30
The oil passage 32 extending from the oil passage 33, the hole 55, and the passage 5
1. The oil passage 34 formed by the annular chamber 53 and the oil passage 35 communicate with the oil chamber 36 in the valve housing 27, and the oil chamber 36 communicates with the oil passage 39, the annular chamber 54, and the passage 52. , and the passage 40 formed by the holes 56 and the oil passages 41 and 42 communicate with the oil tank 31.

Note that the valve housing 27 that constitutes the hydraulic control mechanism
The structure and function of the oil chamber 36 and spool valve 25 are the same as those of a hydraulic control mechanism used in a normal power steering device, so further detailed explanation will be omitted, but in the case of this embodiment, The spool valve 25 is formed into a cylindrical shape, and a return spring 61 is provided inside the spool valve 25 between the control ear opening, the door 15, and the valve housing 27.
Even if it moves together with the Q steering rod 9, the spool valve 25 is configured to be able to return to the neutral position with respect to the valve housing 27 following the movement.

Next, referring to FIG. 2B, which shows the left half of the apparatus according to the embodiment of the present invention, an example of the configuration of the control mechanism C is shown there. The configuration of this control mechanism C was previously proposed by the applicant in Japanese Patent Application No. 59-48054, but as is clear from FIG. 2A, the spool valve 25 of the hydraulic control mechanism and The connected control rod 15 is held slidably in the vehicle width direction, and its movement axis is shown as ρ. This control mechanism C is equipped with a swing arm 71, and the base end of the swing arm 71 is pivotally connected to a holder 73 attached to one end of a rotation shaft 72 by a pin 74. There is. Holder 73
The pivot shaft 72 to which the swing arm 71 is attached is supported by the housing 8 so as to be rotatable about an axis "ri ri z" orthogonal to the movement axis 11 of the control rod 15, and pivots the swing arm 71. The pin 74 is double-ringed!, ,1.
, and is supported by the holder 73 so as to be perpendicular to the axis 12 . therefore,
As the shaft 72 rotates, the angle of inclination between the axis of the pin 74 and the axis 11 changes. In other words, the surface (centered on the pin 74) of the sliding raceway surface perpendicular to the axis 11 (this surface is referred to as "
The angle of inclination with respect to the base 4 (referred to as "plane") will change.

On the other hand, the tip of the swing arm 71 and the control rod 15 are
They are connected via ball joints 75 and 76 and a connecting member 77. Although the connection length of the connection member 77 is adjustable, it is assumed that sufficient rigidity in the axial direction is ensured.

Due to such a connecting member 77, the distance between the ball joint 75 at the tip of the swing arm 71 and the ball joint 76 at the base end of the control rod 15 is always maintained constant. Therefore, if the ball joint 75 is displaced in the left-right direction in FIG. 2B, the control blade 5 will be moved in the left-right direction along the axis l in accordance with this displacement.

The connecting member 77 is supported by a rotation imparting arm 80 at a portion near the ball joint 75, and this arm 80 is a large diameter umbrella rotatably supported by a pin 81 fixed on the axis 11. It is provided integrally with the gear 82. The connecting member 77 is supported by a ball joint 83 that is slidably provided in a direction orthogonal to the axes, and the shaft 14 shown in imaginary lines in FIG. 2B is connected to the control mechanism C. is an input shaft 14, and this input shaft 14
As is clear from FIG. 1, the steering wheel 2 is rotated in accordance with the rotation angle of the steering wheel 2. A bevel gear 84 that engages with the bevel gear 82 is attached to the tip of the input shaft 14, and rotation of the steering wheel 2 is transmitted to the rotation imparting arm 80. Therefore, the swinging arm 71 is swung about the pin 74 by an amount corresponding to the rotation angle of the steering wheel 2, but the input shaft 14
When the rotation imparting arm 80 is rotated by the rotation of , and the swinging arm 7I is rotated about the pin 74 in response, when the axis of the pin 74 coincides with the axis 11, Since the ball joint 75 at the tip of the movable arm 71 only rotates on the reference plane, the control rod 1
5 remains stationary. However, if the axis of the pin 74 is inclined with respect to the axis I11, this pin 74
As the swing arm 71 swings around the center, the ball joint 75 is displaced in the left-right direction in FIG. 2B, and this displacement is transmitted to the control rod 15 via the connecting member 77.
The control rod 15 moves along the axis 11 and actuates the spool valve 25 of the hydraulic control mechanism. Even if the swinging angle of the swinging arm 71 about the axis of the pin 74 is the same, the displacement of the ball joint 75 in the left-right direction in FIG. It will change as the rotation angle changes.

In order to change the inclination angle of the pin 74 with respect to the axis P, that is, the inclination angle of the holder 73 with respect to the reference plane, a sector gear 90 as a worm wheel is attached to the rotation shaft 72 of the holder 73, as is clear from FIG. is attached, and a worm gear 91 that engages with this sector gear 90 is provided on a rotation shaft 92. A bevel gear 93 is attached to this rotary shaft 92, and a rotating shaft 9 of a pulse motor 21 is attached to this bevel gear 93 in order to change the aforementioned steering ratio θ/θ.
By engaging the bevel gear 95 on 4, the angle of inclination of the holder 73 with respect to the reference plane is changed. The motor 21 is attached to the left end of the housing 8 in a corner space between the cylindrical casing 8a and the storage casing 8b, and the rotation shaft 94 of the motor, which is the second input shaft to the control mechanism C, is aligned with the axis 11. arranged in parallel. A cover 97 is attached to the motor 21. Further, the shaft 72 of the holder 73 is extended into a cylindrical body 62 that extends upward integrally with the housing 8, and a steering ratio sensor 2 including a potentiometer or the like is attached to the upper end.
4 is installed. The tilt angle of the holder 73, that is, the rotation angle of the shaft 72 is detected by the steering ratio sensor 24.

Figure 6 shows the vehicle speed and steering ratio θ when controlling the motor 21,
/θF (here, θ is the front wheel steering angle, and θ8 is the rear wheel steering angle)
It is a graph showing the relationship between When the vehicle speed is low, in order to improve the turning performance of the vehicle, the rear wheels need to be steered in the opposite direction to the front wheels, that is, with the opposite phase, and therefore the steering ratio is negative. When approximately 40 kn+/hr is reached, the steering ratio becomes zero and the rear wheels are not steered regardless of the steering angle of the front wheels. When driving at high speeds, the rear wheels are steered in the same direction as the front wheels, that is, in the same phase, in order to improve the grip of the rear wheels during cornering and enhance stability. In order to change the steering ratio according to the vehicle speed in this way, a control mechanism C is provided, and the steering ratio sensor 24 used therein controls the motor 21 to obtain a desired steering ratio. Because tires play such an important role, it is necessary to protect them from being damaged by stones and other objects thrown up by the tires while the vehicle is running. Therefore, as is clear from FIG. 3, the steering ratio sensor 24 is provided above the rear wheel steering rod 9.

FIG. 7 shows an example of a control circuit 23 for controlling the motor 21 to change the steering ratio according to the vehicle speed detected by the vehicle speed sensor 22. 101, a comparison circuit 102 and a drive circuit 103, the discrimination circuit 101 receives a vehicle speed signal from the vehicle speed sensor 22, the comparison circuit 102 receives a discrimination signal from the discrimination circuit 101, and Ratio sensor 24
A steering ratio signal is manually inputted from the steering ratio signal, and the drive circuit 103 drives the motor 21 based on the result of comparing this discrimination signal with the steering ratio signal.

Referring now to FIGS. 8 and 9, a configuration for mounting the apparatus of the present invention on a vehicle is shown. In the figure, 10
Reference numeral 5 denotes a subframe extending in the vehicle width direction that is attached to the main frame (not shown), and one rear wheel 7L is connected to a suspension arm 106 whose one end is pivotally supported by this subframe 105, and a strut (Fig. (not shown) and links 107. subframe 10
Brackets 108 as shown in the figure are fixed by welding at two locations spaced apart from each other by a predetermined distance in the left-right direction on the front side of the bracket 5 . This bracket 108 has a flat front wall 109 that forms a mounting surface that extends forward and upward on the front side of the subframe 105, and a flat front wall 109 that is bent rearward from both sides of this front wall 109'. In frame 105? 8
It consists of left and right side walls 110 that are in contact with each other.

On the other hand, as shown in FIGS. 2A, 2B, 3, and 4, the cylindrical casing 8a housing the rear wheel steering loft 9 has a A pair of mounting flanges 63 are integrally formed at the predetermined interval in the axial direction of the cylindrical casing 8a. This mounting flange 63 has two mounting bolt holes 64 arranged vertically, and bolts 65 and nuts 6.
6 is tightly fixed to the front surface of the flat front wall 109 of the bracket 108, thereby firmly attaching the device of the present invention to the subframe 105.

As is clear from the above description, in the present invention, the power cylinder 12 of the power steering device that assists the movement of the rear wheel steering rod 9 in the vehicle width direction has a cylindrical shape that slidably supports the rear wheel steering rod 9. Since the housing 8 is formed integrally with the casing 8a, and the housing 8b is formed integrally with the cylindrical casing 8a and the storage casing 8b which houses the control mechanism C and the hydraulic control mechanism, the rear wheel steering mechanism is The configuration is simple and compact, making it easier to mount on a vehicle.

Furthermore, as in the embodiment, by attaching the oil pan 43 to the lower part of the storage casing 8b and filling the oil pan 43 with lubricating oil, the lubricity for the control mechanism C is improved.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram schematically showing the overall configuration of a four-wheel steering system for a vehicle according to the present invention, and FIG. 2 shows the right half and left half of the embodiment of the present invention as FIGS. 2A and 2B, respectively. The overall view shown in FIG. 3 is a cross-sectional view along the mm line of the second B circle,
Figure 4 is a sectional view taken along line IV-IV in Figure 2B, Figure 5 is a partially sectional bottom view showing the motor drive part in Figure 2B, and Figure 6 shows the relationship between vehicle speed and steering ratio. Graph, Fig. 7 is a block circuit diagram showing an example of control for changing the steering ratio, Fig. 8 is a plan view showing the rear part of the vehicle body to which the rear wheel steering mechanism is installed, and Fig. 9 is the IX of Fig. 8. It is a sectional view along -■. IL, IR-Front wheel 2--Steering wheel 7
L, 7R - Rear wheel 8a - Cylindrical casing 8b - Storage casing 9 - Rear wheel steering rod 12 - Power cylinder 12a, 12b - Hydraulic chamber 13 - Piston
14.--Human power shaft 15-Control rod 20-Cylindrical body 2I...Pulse motor 22.--IR speed control 4j
24 - Rotary fG ratio sensor 25 - Spool pulp 26 series connection part 27 - Pulp housing 43 - Oil pan 63... Mounting flange 71 - Swing arm
72 Rotating wheel 73 - Holder 77... Connecting member 94 - Rotating shaft of motor 105 - Sub frame 108 - Mounting Brakent Patent applicant Mazda Motor Corporation NSK Ltd. agent Patent attorney Hitoshi Yamamoto Hitoshi 4 Figure 6 Figure 7 Procedural Amendment (Method) November 12, 1985 Mr. Michibu Uga, Commissioner of the Patent Office ■, Indication of the case: Japanese Patent Application No. 176959/1982 2, Title of the invention: Four-wheel steering device for vehicles 3 , Relationship with the person making the amendment Patent applicant name (313) Mazda Motor Corporation 4, agent address 105 Address 1-20-6-5 Toranomon, Minato-ku, Tokyo Date of amendment order October 29, 1985 Day 6, Column 7 for a brief explanation of the drawings in the specification subject to amendment, Contents of the amendment (1) In the specification, page 22, lines 9 to 11, "Figure 2 is one... "Overall Diagram," shall be amended as follows. 2A is a front view showing the right half of an embodiment of the present invention as a partial cross section, and FIG. 2B is a front view showing the left half of the same as a partial cross section.

Claims (1)

[Scope of Claims] 1. In a four-wheel steering system for a vehicle configured to steer both the front wheels and the rear wheels by operating a steering wheel, the rear wheel steering rod whose operation is assisted by the power steering system is configured to steer the rear wheels along with the front wheels by operating a steering wheel. A storage casing for a control mechanism that is provided to penetrate through the power cylinder of the steering device and that controls the operation of the rear wheel steering rod in response to a rear wheel steering input related to operation of the steering wheel; A four-wheel steering device for a vehicle, characterized in that it is formed integrally with a power cylinder section. 2. The control mechanism includes a control rod that can be displaced in the vehicle width direction in response to the rear wheel steering input, and the control rod is arranged in parallel with the rear wheel steering rod via a connecting portion, and 2. The device according to claim 1, wherein the rear wheel steering rod is moved in the vehicle width direction through the power steering device in response to displacement of a control rod. 3. A lower part of the storage casing of the control mechanism is covered by an oil pan, and the oil pan is filled with lubricating oil for lubricating the control mechanism. Apparatus described in section.