JPS6220949B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power steering system for an automobile or other vehicle, and particularly to a steering wheel having a pinion shaft connected to a steering wheel and a pinion of the pinion shaft in a gear box. The present invention relates to a power steering system comprising a series of rack rods and a switching valve that can selectively connect left and right oil chambers of a power cylinder that hydraulically drives the rack rods to a hydraulic power source and an oil reservoir.

The present applicant has developed a power steering system of this kind in which a pinion shaft is supported on a rocking cage that is rotatably supported by a gear box with a certain amount of eccentricity with respect to the axis of the pinion shaft, and a steering torque is applied to the pinion shaft. A device has already been proposed in which the swinging basket rotates about its axis when the oscillating cage is applied, and the pivoting motion causes the switching operation to occur in the switching valve. The structure is simple, and the switching valve can be of any type, such as a spool type or a rotary type, independently of the pinion shaft, so it is easy to obtain a small size and fewer sealing members. As a result, the switching valve can be made to respond accurately to the steering torque, and the installation position of the switching valve can also be freely selected around the swing cage, resulting in a smaller overall size and no space constraints when installed on an actual vehicle. It has the following effects.

The present invention improves the above-mentioned device, and when steering is performed in a state where the hydraulic system is malfunctioning, the rotation of the rocking cage is limited to a certain angle, and the steering torque applied to the pinion shaft directly controls the rack rod. To provide the device which enables so-called manual steering of the oscillating cage, improves the manufacturability of the rotating stopper surface and the switching pin provided respectively on the oscillating cage, and always ensures stable quality. The purpose is to

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. Reference numeral 1 denotes a gear box fixed to the vehicle body, and the inside thereof is connected to the knuckle arm of the steering wheel via a tie rod (none of which is shown). 2 is slidably penetrated therethrough, and a pinion 3a of a pinion shaft 3 connected to a steering handle (not shown) meshes with the rack 2a of the rack rod 2.

The pinion shaft 3 is rotatably supported by a rocking cage 4 enclosing the pinion 3a via a pair of upper and lower bearings 5, 5'. , 6'. The pinion shaft 3 and the swing cage 4 have different axes from each other, and in the illustrated example, the pinion shaft 3
The axis O ₄ of the swing cage 4 is offset by ε toward the rack rod 2 with respect to the axis O ₃ of the swing cage 4 .

A first window 7 for avoiding interference with the rack 2a and a second window 7' for reducing weight are provided on the intermediate peripheral wall of the swinging cage 4, facing each other. Rack 2a and pinion 3a mesh through window 7. A pair of flat stopper surfaces 4a and 4b are provided on both side edges of the second window 7' parallel to the axis _O4 of the swinging cage 4.
are formed as bulges, and normally these stopper surfaces 4a,
A pair of catch seats 1 facing each other with a certain gap at 4b
a and 1b are formed as protuberances on the inner wall of the gear box 1, and the rotation around the axis O4 of the swinging cage 4 is kept constant by contact between the stopper surface 4a and the catch 1a, or between the stopper surface 4b and the catch _1b . It is now limited to angles.

An operating pin 8 for a switching valve 9 is provided protruding from the lower end surface of the swinging cage 4 at a distance l that exceeds the eccentricity ε from its axis O ₄ .

The switching valve 9 can be of any type as long as it is a four-way switching valve, but in the example shown, it is a valve box 10 fixed to the gear box 1 and a spool valve 12 that slides into the valve hole 11 of the valve box 10.
The spool valve 1 is configured in a spool type.
The tip of the operating pin 8 is engaged with a cutout groove 13 extending in the radial direction of the swinging cage 4 provided at one end of the swinging cage 2, so that the swinging cage 4 rotates around its axis _O4 . The spool valve 12 can be operated left and right via the operating pin 8.

The spool valve 12 has three annular grooves 14, 15, and 16 on its outer circumferential surface, and the central groove 15 is connected to a hydraulic source 18 such as a hydraulic pump through a supply oil passage 17 that opens to the valve hole 11. Also, groove 1 on both sides
4 and 16 are in communication with the oil reservoir 20 via return oil passages 19 connected to the hollow portion 12a of the spool valve 12, respectively. On the other hand, the valve case 10 is provided with two annular grooves 21 and 22 arranged on the inner peripheral surface of the valve hole 11 so as to sandwich the open end of the supply oil passage 17, and these grooves are formed on the rack rod 2. Power cylinder 2
It communicates with the left and right oil chambers A and B in 3 through output oil passages 24 and 25.

Therefore, if the spool valve 12 is displaced from the illustrated neutral position to the right or left, one of the left and right oil chambers A and B of the power cylinder 23 is connected to the supply oil passage 17.
The other end is selectively connected to the return oil passage 19, and as a result, pressure oil from the hydraulic source 18 is supplied to the oil chamber connected to the supply oil passage 17, and the rack rod 2 is moved by the hydraulic pressure. It can be driven to the right or left to turn the steering wheels.

A reaction mechanism 26 is attached to the switching valve 9 in order to normally maintain the spool valve 12 in the neutral position shown. The mechanism 26 includes a cylinder hole 27 provided in the valve case 10 parallel to the valve hole 11, a pair of pressure receiving pistons 29 and 29' that slide into the cylinder hole 27 and define a reaction chamber 28 therein, and both pressure receiving pistons 29. , 29' outwardly, and a pair of abutment pins 31, 3 that protrude from one side of the spool valve 12 and clamp the pressure receiving pistons 29, 29'.
1', both pressure receiving pistons 2
9 and 29' are regulated in their outward movement by the inner surfaces of the left and right lids 10a and 10b of the valve case 10, and the reaction chamber 28 is connected to the annular groove 15 in the center of the spool valve 12, and thus to the supply oil path. It communicates with 17. Further, relief grooves 32, 32' are provided in the portions of the valve case 10 facing the abutment pins 31, 31' to avoid interference with the pins 31, 31' when the spool valve 12 is operated.

The gear box 1 includes a guide piston 3 that slidably supports one side of the rack rod 2 on the opposite side from the pinion 3a.
4 is fitted, and a cap 36 is screwed on with the spring 35 in between, and the resilient force of the spring 35 presses the rack rod 2 toward the pinion shaft 3 via the guide piston 34, thereby tightening the rack 2a and the pinion 3a. It is designed to eliminate the crushing of the meshing part.

Next, to explain the operation of this embodiment, when no steering torque is applied to the pinion shaft 3, the neutral return spring 30 is activated by the pressure receiving piston 29,
29' are held in contact with the lids 10a and 10b, the spool valve 12 is held in the neutral position by these pistons via the pair of abutment pins 31 and 31', and the two grooves of the valve hole 11 are held in the neutral position. annular groove 21, 2
2 are connected to the supply oil passage 17 and the return oil passage 19 at the same time, so that the power cylinder 2
3 remains inactive. When the spool valve 12 is in the neutral state, the axis O3 of the pinion shaft ₃ is located on the extension line L of the straight line connecting the axis _O4 of the swing cage 4 and the meshing point of the rack 2a and pinion 3a.

Therefore, if you try to drive the rack 2a in the axial direction from the pinion 3a by applying steering torque to the pinion shaft 3 via the steering handle, a reaction force will be generated from the rack 2a to the pinion 3a depending on the magnitude and direction of the driving force. This reaction force causes the pinion shaft 3 to rotate together with the swing cage 4 around the axis O ₄ of the swing cage. When this turning moment exceeds the opposing moment due to the set load of the neutral return spring 30, the above-mentioned turning starts, and the angular displacement of the pinion shaft 3 around the axis _O4 is expanded by the lever ratio l/ε. As a result, the actuating pin 8 gives sufficient axial displacement to the spool valve 12 to reliably cause the switching operation, so that the power cylinder 23 operates to assist the pinion shaft 3 in driving the rack rod 2.

On the other hand, due to the switching operation of the switching valve 9, the reaction mechanism 26
The working pressure of pressure oil supplied from the supply oil path 17 to the power cylinder 23 is introduced into the reaction chamber 28,
This pushes the pressure receiving pistons 29, 29' outward and applies a reaction force to the spool valve 12 via the contact pins 31, 31' to return it to the neutral position. Excessive switching operation is suppressed.

According to steering in an emergency when pressure oil cannot be supplied to the supply oil passage 17 due to damage to the transmission member that drives the hydraulic power source 18 or failure of the engine, the rotation of the swing cage 4 causes the rotation of the hydraulic oil from the operating pin 8. Spool valve 12
Even if you move the power cylinder 23, the power cylinder 23 cannot be operated, but when the rotation of the swing cage 4 reaches the set angle,
The stopper surface 4a or 4b is the catch 1a or 1b.
Since the swing cage 4 is stopped by colliding with the pinion shaft 3, the steering torque applied to the pinion shaft 3 directly drives the rack rod 2 to enable manual steering, and the course of the vehicle can be changed safely. In this case, since a large load due to the steering torque does not act on the operating pin 8 and the spool valve 12.
etc. can be set low.

As described above, according to the present invention, the peripheral wall of the oscillating cage that responds to the steering torque of the pinion shaft cooperates with the catch provided protruding from the inner wall of the gear box to limit the rotation of the oscillating cage to a certain angle. A stopper surface is formed to stop the swing cage, and an operating pin that operates the control valve is provided protruding from the end face of the swing cage, so the rotation of the swing cage is quickly restrained when steering is performed when the hydraulic system is malfunctioning. This enables manual steering by directly driving the rack rod from the pinion shaft, ensuring fail-safety.

Particularly in this case, since the peripheral wall of the swinging cage has sufficient rigidity, the stopper surface on the surrounding wall reliably supports the rotational torque of the swinging cage based on the steering torque, and the operating pin and control valve are It can protect against loads and prevent changes in characteristics due to deformation. In addition, since the stopper surface and the actuating pin are formed at different locations on the swing cage, there is no problem of accumulation of manufacturing errors, and it is easy to form the actuating pin, which requires particularly high precision, resulting in stable quality. It is something that contributes.

[Brief explanation of the drawing]

The drawings show one embodiment of the device of the present invention, and FIG. 1 is a vertical side view of the entire device, and FIGS.
The figure is a sectional view taken along lines - and - of Figure 1, and Figure 4.
and FIG. 5 are a front view and a side view of the swinging basket. A, B...Oil chamber, _O3 ...Pinion shaft center,
O ₄ ...Axis of rocking cage, ε ... Eccentricity, 1 ... Gear box, 1a, 1b ... Seat, 2 ... Rack rod, 2
a... Rack, 3... Pinion shaft, 3a... Pinion, 4... Rocking basket, 4a, 4b... Stopper surface, 8... Operating pin, 9... Switching valve, 18... Hydraulic source, 20 ...Oil sump, 23...Power cylinder.

Claims (1)

[Claims] 1. A pinion shaft connected to a steering handle, a rack rod connected to a steering wheel whose rack is meshed with a pinion of the pinion shaft in a gear box, a power cylinder capable of hydraulically driving the rack rod, and a power cylinder that can hydraulically drive the rack rod; In a power steering device comprising a switching valve capable of selectively connecting left and right oil chambers to a hydraulic power source and an oil reservoir, respectively, the pinion shaft is eccentrically centered by a certain amount with respect to its axis, and the pinion shaft is attached to the gear box. It is supported on a swinging cage that is rotatably supported, so that when a steering torque is applied to the pinion shaft, the swinging cage rotates around its axis, and the swinging cage is supported on a peripheral wall of the swinging cage. A stopper surface is formed that cooperates with a catch protruding from the inner wall of the gear box to limit the rotation of the swinging cage to a certain angle, and an operating pin for operating the control valve is provided on the end surface of the swinging cage. A protruding power steering device for a vehicle.