JPS6134209Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a power steering device for reducing the operating force of a steering wheel in an automobile.

In order to prevent the link mechanism of the steering device from being damaged due to unrestricted rotation of the steering wheel, a knuckle stopper, a pittman stopper, or the like is provided to limit rotation of the steering wheel within a predetermined range. However, in a steering device including a power steering device, the nutcle or pitman arm exerts a large load on the stopper, which may cause damage to the stopper.

An object of the present invention is to provide a power steering device that can prevent damage to a stopper while ensuring power steering operation in the return direction.

Next, embodiments of the present invention will be described with reference to the drawings.

The steering wheel 1 is connected to the upper end of a steering shaft 2, which extends at its lower end into a gear housing 3. Inside the gear housing 3, there is a power cylinder 4,
A control valve 5 and a sector 6 are housed. The piston 9 of the power cylinder 4 engages with the worm 10 of the steering shaft 2 on its inner circumferential surface, and engages with the sector 6 on its outer circumferential surface. Sector 6 is connected to Pittman arm 11. At both ends of the piston 9 are oil chambers 13,
14 are provided facing each other.

Plates 21 and 22 are supported at the lower end of the steering shaft 2 via bearings 19 and 20, respectively, and a spool 23 of the control valve 5 is disposed between the plates 21 and 22. Both ends of the spool 23 are in contact with the plates 21 and 22. A plunger 2 is further provided between the plates 21 and 22.
A spring 24 is arranged which abuts 5, 26 at both ends. An annular groove is formed in the inner peripheral surface portion of the gear housing 3 surrounding the spool 23.

The control valve 5 has an inlet 31 connected to the oil pump 30, an outlet 33 connected to the oil reservoir 32, and in relation to the axial position of the spool 23:
It has ports 34 and 35 that selectively generate hydraulic pressure for operating the piston 9.

The operation of the control valve 5 will be schematically explained. When traveling straight, the spring 24 maintains the steering shaft 2 and therefore the spool 23 in a neutral position with respect to the gear housing 3. As a result, the hydraulic pressure from the inlet 31 is returned to the oil reservoir 32 through the outlet 33 without being sent to the power cylinder 4. When the steering wheel 1 is rotated to the right for a right turn, the worm 10 tries to move toward the piston 9 oil chamber 14, but due to the large ground resistance transmitted through the sector 6, the piston 9 movement is initially blocked. Therefore, the steering shaft 2 is moved against the spring 24 to the first position.
In the figure, it moves to the left with respect to the gear housing 3, and the spool 23 also moves to the left. In this way, the annular groove on the inner peripheral surface of the gear housing 3 and the spool 23
The gap between the port 35 and the land changes, and a large hydraulic pressure is generated at the port 35. When the steering wheel 1 is rotated to the left for a left turn, the spool 23 moves to the right in the figure, and a large hydraulic pressure is generated in the port 34.

The electromagnetic switching valve 41 as a two-position switching valve has a coil 42, and when the coil 42 is energized, it is maintained at the A position to cut off the connection between the ports 34, 35 and the oil chambers 13, 14, and the coil 42 is energized. 42 is maintained at the B position to connect the port 35 to the oil chamber 13 and the port 34 to the oil chamber 14. The electromagnetic switching valves 45a, 45b as 3-position switching valves have coils 46a,
46b and 47a, 47b, and when only one solenoid 46a, 46b is energized, it is maintained at the C position, and both solenoids 46a, 46b are energized.
When solenoid a, 47a and 46b, 47b are both deenergized, the solenoid is maintained at the D position, and when only the other solenoid 47a, 47b is energized, it is maintained at the E position.

An oil passage 48 is provided between the electromagnetic switching valves 45a and 45b.
49 is provided, and check valves 50 and 51 are provided in the oil passages 48 and 49, respectively. The check valve 50 prevents the flow of hydraulic pressure from the electromagnetic switching valves 45a to 45b, and the check valve 51 prevents the flow of hydraulic pressure from the electromagnetic switching valves 45b to 45a.
prevent the flow of hydraulic pressure to. As a result, either one of the solenoids 46a, 46b or 4
7a, 47b are energized, the port 35 is connected to the oil chamber 13, and the port 34 is connected to the oil chamber 1, similar to the connection when the electromagnetic switching valve 41 is in the B position.
Connected to 4.

Limit switches 55 and 56 are arranged on both sides of the swinging pitman arm 11, respectively.
The limit switches 55 and 56 are provided at positions where they abut the pitman arm 11 before the pitman arm 11 abuts a pitman stopper (not shown). As shown in FIG. 4, the limit switches 55, 56 are connected at one end to a DC power source 57,
When the limit switch 55 is closed, the coils 42, 46a, 46b are energized, and when the limit switch 55 is closed, the coil 4 is energized.
2, 47a, 47b are energized.

A case in which the steering wheel 1 is rotated to the right for a right turn will be described.

When the amount of clockwise rotation of the steering wheel 1 is below a predetermined value, the pitman arm 11 is away from the limit switches 55, 56, both limit switches 55, 56 are maintained open, and the coils 42, 46a, 46b, 47a, 47b are turned off. Forced. Therefore, the electromagnetic switching valve 41 is maintained at the B position, and the electromagnetic switching valves 45a and 45b are maintained at the D position. When the steering wheel 1 rotates clockwise, a predetermined oil pressure is generated at the port 35 in the control valve 5, and this predetermined oil pressure is applied to the electromagnetic switching valve 4.
1 to the oil chamber 13 to move the piston 9 toward the oil chamber 14, and the oil pressure in the oil chamber 14 is sent to the port 3.
It is discharged from 4. The movement of the piston 9 by hydraulic pressure applies a force to the sector 6 that is added to the operating force of the steering wheel 1, so the operating force is reduced. When the amount of clockwise rotation of the steering wheel 1 reaches a predetermined value, the pitman arm 11 comes into contact with the limit switch 55, and the limit switch 55
becomes closed. As a result, the coils 42, 47a,
47b is energized, the electromagnetic switching valve 41 is maintained at the A position, and the electromagnetic switching valves 45a and 45b are maintained at the E position. Due to the clockwise rotation of the steering wheel 1, a predetermined hydraulic pressure is still generated in the port 35, but the hydraulic pressure from the port 35 to the oil chamber 14 is reduced by the check valves 51 and 50 between the electromagnetic switching valves 45a and 45b. Since the supply of oil pressure and the discharge of hydraulic pressure from the oil chamber 13 to the port 34 are prevented, movement of the piston 9 toward the oil chamber 14 is prevented. In this way, since the operating force is not reduced by hydraulic pressure, the pitman arm 11 lightly contacts the pitman stopper and stops its movement. When the driver returns the steering wheel 1 from this state, the steering wheel 1 is rotated to the left, and a predetermined hydraulic pressure is generated in the port 34 at this time. The limit switch 55 remains closed until the rotation of the steering wheel 1 returns to a predetermined range, and the ports 34 and 35 are closed to the oil chambers 14 and 13 by the electromagnetic switching valves 45a and 45b, respectively.
However, the check valves 50 and 51 allow the supply of hydraulic pressure from the port 34 to the oil chamber 14 and the discharge of hydraulic pressure from the oil chamber 13 to the port 35.
The operating force when returning the steering wheel 1 is reduced.

When the steering wheel 1 is rotated to the left for a left turn, oil pressure is generated in the port 34, and when the amount of left rotation of the steering wheel 1 is within a predetermined range, the limit switch 56 is open and the predetermined oil pressure is output from the port 34. is supplied to the oil chamber 14 via the electromagnetic switching valve 41 to move the piston 9 into the oil chamber 13.
Move it toward to reduce the operating force. When the amount of left rotation of the steering wheel 1 exceeds a predetermined range,
The limit switch 56 is closed, and the solenoid switching valve 4
5a, 45b are maintained at the C position, and the check valves 51,
50 prevents the supply of hydraulic pressure from the port 34 to the oil chamber 14 and the discharge of hydraulic pressure from the oil chamber 13 to the port 35, thereby preventing the pitman arm 11 from abutting against the pitman stopper with a large force. When the steering wheel 1 that has rotated counterclockwise is returned to a predetermined range, the oil is supplied from the port 35 to the oil chamber 13 via the check valve 50 and from the oil chamber 13 via the check valve 51 despite the limit switch 56 being closed. Since hydraulic pressure is allowed to be discharged from the oil chamber 14 to the port 34, the operating force can be reduced.

As described above, according to the present invention, when the amount of rotation of the steering wheel 1 is within a predetermined range, normal power steering operation is performed, and when the amount of rotation of the steering wheel 1 exceeds a predetermined range, the power steering is rotated in the direction of increasing steering. In contrast, the power steering operation is stopped, and the power steering operation is performed only for rotation in the reverse direction. Therefore, a large load is prevented from acting on the stopper provided to limit the amount of rotation of the steering wheel 1, and a good power steering operation in the return direction is ensured. According to the present invention, when the amount of rotation of the steering wheel exceeds a predetermined range, the oil is prevented from flowing against rotation in the increasing direction, so it is possible to omit the stopper.

Note that the electromagnetic switching valves 41, 45a, and 45b may be provided outside or inside the gear housing 3.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the entire power steering device of the embodiment, FIG. 2 is a diagram showing the control valve in detail, and FIG. 3 is a diagram showing the control valve in detail.
The figure is a hydraulic circuit diagram showing the connection between the port of the control valve and the oil chamber of the power cylinder, and FIG. 4 is a control circuit diagram of the electromagnetic switching valve. 1... Steering wheel, 5... Control valve,
9... Piston, 13, 14... Oil chamber, 34, 3
5...Port, 41...Solenoid switching valve (first connection means), 45a, 45b...Solenoid switching valve, 46
a, 46b...Coil (second connection means), 47
a, 47b...Coil (third connection means), 5
0,51...Check valve, 55,56...Limit switch.

Claims (1)

[Scope of utility model registration request] a control valve having first and second ports and controlling hydraulic pressure generated in the first and second ports in relation to rotation of the steering wheel; A piston that moves by hydraulic pressure to apply a force that is added to the operating force of the steering wheel, and connects the first port to the first oil chamber and the second port only when the amount of rotation of the steering wheel is within a predetermined range. a first connecting means respectively connected to the second oil chamber; a first check valve for blocking the flow of hydraulic medium from the first or second port to the first or second oil chamber; a second check valve that blocks the flow of hydraulic medium from the second oil chamber to the first or second port;
second connecting means for connecting the first and second ports to the first and second oil chambers via the first and second check valves, respectively;
and when the amount of rotation of the steering wheel exceeds the predetermined range in the second direction, the first and second ports are connected to the first and second oil chambers via second and first check valves, respectively. A power steering device characterized by comprising a third connection means for connecting to.