JPS6149146B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to power steering systems for motor vehicles.

A power piston comprising a rotor (valve inner) that rotates integrally with the steering handle, a worm end that cooperates with the rotor to form a throttle valve mechanism, and engages with the worm, and a rack possessed by the power piston. A power steering system has already been provided which includes a sector gear that engages with a rack, a sector shaft that supports and fixes the sector gear and that is in turn interlocked with a steering wheel. A power steering system has already been provided in which a reaction piston mechanism is further attached to the power steering system and the reaction piston mechanism receives power assist hydraulic pressure to obtain a resistance force, that is, a reaction force to the steering wheel operation.

In the power steering system of the present invention, the hollow lumen of the worm is communicated with one pressurizing chamber, and the hydraulic pressure is guided to the pressure receiving chamber of the reaction piston through this lumen. Eliminates the need to provide hydraulic passages in the wall,
Furthermore, the reaction piston and the rotor are connected by a pin connection to achieve smooth and reliable operation and a simple structure. The apparatus of the present invention will be explained in the following figures.

In FIG. 1, the right input shaft 3 is connected to a steering shaft (not shown) through a spline 3c carved on the outer circumferential surface of its right end so as to be capable of transmitting torque. The input shaft 3 has a hollow tubular shape, and a torsion bar 10 passes through the hollow space leaving a suitable gap between the input shaft 3 and the inner circumferential surface of the hollow. The right end of the torsion bar 10 is fixed to the input shaft 3 by a pin 11, and the left end is connected to the worm 4 by a pin 12 in a hollow part of the worm 4 so as to be rotatable together. The worm 4 has a worm spiral formed on the outer peripheral surface of the left half, and this is passed through the ball 5,
It engages with an internal thread on the inner peripheral surface of the piston power 6 (abbreviated as piston).

The piston 6 engages a rack 6' on its lower surface with a sector gear 7'. The sector gear 7' is fixed on the sector shaft 7, and the other end of the sector shaft 7 is provided with a well-known pitman arm (not shown), which is connected to the steering wheel via a drag link, a knuckle arm, etc. in this order. is connected to constitute a steering mechanism. The right end of the worm 4 becomes a huge hollow part,
It is rotatably supported by the cover 2. The left end of the worm 4 is pivotally supported on the inner end surface of the housing 1. The piston 6 divides the internal space of the sealed housing 1 into left and right pressurized chambers 8a and 8b.

The cover 2 at the right end of the housing has a port 8 at the top for receiving the discharge flow from the pump, and a port 9 at the bottom for discharging the pump flow. M indicates a motor for driving the pump, and R indicates a reservoir. When the steering gear is in neutral, the liquid flow from the upper port 8 is
It passes through the steering system without resistance and is discharged into the reservoir R from the lower port 9. When an attempt is made to rotate the steering wheel from its neutral position to either the left or right direction, the above-mentioned liquid flow is throttled by the throttle valve device, which will be described in detail below, and the pressure upstream thereof increases, and under this influence, the pressure chamber 8a , 8b is pressurized, and the other pressurized chamber is maintained in communication with the atmosphere. Therefore, piston 6
is pressurized to either side. As a result, the sector gear 7' is driven via the rack 6'. Steering is performed by changing the direction of the steering wheels through the mechanisms below the sector shaft 7.

Next, a throttle valve device for generating a throttle-based resistance in the pump flow and thus generating hydraulic pressure will be described below. A valve sleeve 4a is tightly fitted into the large hollow portion 4' at the right end of the worm 4, and as shown in FIG. 2, the valve sleeve 4a is connected by a pin 13 so that they can rotate together. The input shaft 3 is further fitted in the hollow interior of the sleeve 4a so as to be able to slide and rotate. The valve sleeve 4a is provided with axial grooves 18 and 19 on its inner circumferential surface, every other groove being spaced at equal intervals. Among these grooves, the groove 18 communicates with the outer circumferential groove 16 of the sleeve 4a through a radial through hole 17.

As shown in FIG. 1, the input shaft 3 has an intermediate portion that serves as a rotor, that is, a valve inner 3a, and constitutes a throttle valve device to be described below. The rotor 3a is the second
As shown in the figure, axial grooves 2 are placed at equal intervals on the outer circumference.
It has 0 and 21 on every other side for a total of 6 sides. These grooves and the grooves 18 and 19 on the inner circumferential surface of the sleeve 4a interfere with each other to perform two types of throttle valve operations.

The enlarged longitudinal cross-sectional view of FIG. 3 shows the pump flow path in the neutral state of the device. The liquid flow from the supply boat 8 on the upper right side flows from the circumferential groove 14 on the outer periphery of the worm end 4', through the radial through hole 15, and into the circumferential groove 16 of the sleeve 4a, the radial through hole 17, and the radial through hole 17 of the sleeve 4a. Groove 1
It reaches 8. Next, in FIG. 2, the liquid flow that has reached each groove 18 collides with the rotor 3a, is divided into two halves, and enters grooves 20 and 21 on both sides. One of the grooves 20 passes through a radial through hole 22 (indicated by dotted lines in FIGS. 1 and 3) and then communicates with the inner cavity 23 of the rotor 3a, leading to the left side of the worm 4 in FIG. Lumen 2
4. Through the radial passage hole 25, the left pressurization chamber 8
Leads to b. As shown in FIG. 3, the other groove 21 communicates with the right pressurizing chamber 8a through a notch 26 and through a radial through hole 27 in the worm end 4'.

Returning to FIG. 2, in short, the groove 20 communicates with the pressurizing chamber 8b, and the other groove 21 communicates with another pressurizing chamber 8a.

Both of the above-mentioned pressurizing chambers are chambers for pressurization, and are so-called dead-end chambers, and therefore are not chambers through which pressurized liquid flows. Therefore, from each through hole 17 to each groove 18 in FIG. 2, left and right grooves 20,
The so-called destination of the liquid flow divided into 21 is another groove 19
There is nothing else. Each groove 19, shown in phantom in FIG. 3, communicates at its right end with the exhaust or return port 9. The pump flow therefore enters through the supply port 8 and eventually passes through the circuit described above with little resistance and returns to the reservoir R through the return port 9.

Next, the characteristic structure of the device of the present invention will be explained.
As shown in the middle of FIG. 3, the left end of the rotor 3a is connected by two pins 29 to two plunger-shaped reaction pistons 30 through an elongated hole 30a as shown in FIG. . As can be seen in FIG. 4, the protrusion 3b on the left end of the rotor is connected to the stepped hole 2 of the worm 4.
Occupies a position within 8. The protrusion 3b is concentric with the torsion bar 10 by the operator's handle operation,
The worm 4 rotates within the stepped hole 28, and at the same time, the worm 4 also rotates in the rotating direction. Therefore, even if the stepped hole 28 has a long cross-sectional shape as shown in FIG. 4, there is no problem in operation. Each reaction piston 30 is slidably fitted into two holes 31 bored in the peripheral wall of the worm 4 . Each hole 31 is provided along the torque direction of the protrusion 3b of the rotor, and the reaction piston therein receives the hydraulic pressure of the pressurizing chamber 8b on the inner surface, and receives the hydraulic pressure of the other pressurizing chamber 8a on the outer surface. Receive pressure. O-ring 32
The two hydraulic pressures in the spaces where the two pressure-receiving surfaces are exposed are mutually isolated and sealed.

Next, the operation will be explained. In FIG. 2, when the operator turns the steering wheel to the right, the rotor 3a also turns to the right.
At the beginning of this rotation, the end 4' of the worm is still stationary, so that instantaneous relative rotation or differential movement occurs between the rotor 3a and the end 4'. As a result, referring to FIG. 2, each groove 18 corresponds to each groove 2.
1 is narrowed, and conversely, communication with each groove 20 is further relaxed. At the same time, the communication between the grooves 20 and 19 is narrowed. Groove 19 is discharge port 9
Since the groove communicates with the groove 20, the pump flow ultimately flows through the groove 20.
The aperture resistance will be experienced between and 19. As a result, the pressure of the pump flow upstream of this throttle point increases. Naturally, the pressure inside the groove 20 also increases, and this increase in pressure is further spread to the radial through hole 22 (the third
Proceed to the left through the lumen 23 through the worm stepped hole 28, the lumen 24, and the radial through hole 2.
5, the pressure inside the left pressurizing chamber 8b is increased. The other pressurizing chamber 8a communicates with the groove 21 through the notch 26 from the radial through hole 27 in the end 4' of the worm, but the groove 21 does not communicate with the upstream groove 18. , as mentioned above, is throttled or shut off by operating the handle. Therefore, the pressurized chamber 8
a does not increase pressure. In short, only the pressurizing chamber 8b is pressurized. As a result, the piston 6 moves to the right in FIG. 1, which is transmitted via the rack 6' and then via the sector gear 7' to steer the steering wheel.

The operation when the steering wheel is turned to the left can be inferred from the above, so the explanation thereof will be omitted.

Next, the reaction force felt by the driver's hand when operating the steering wheel will be explained. Resistance transmitted from the steering wheel to the steering wheel during steering operation is transmitted from the sector shaft 7 (Fig. 1) to the sector gear 7', rack 6', piston 6, worm 4, torsion bar 10, and input shaft 3.
is transmitted to the handle via the At this time, the torsion bar 10 receives a torsional load due to torque between both ends thereof, and is subjected to torsional distortion. However, the worm 4 rotates following the rotor 3a so as to eliminate the twist. That is, when operating the handle, the rotation angle of the sleeve 4a is slightly delayed compared to the rotor 3a of FIG. 2, corresponding to this torsional distortion. As described above, this delay acts as a throttle valve operation for the pump flow, and a pressure difference is generated between the pressurizing chambers 8a and 8b, in other words, between the pressure receiving surfaces of the piston 6. This differential pressure drives the piston 6 in either direction. This driving force is converted into torque and transmitted to the worm 4 via the ball 5. The direction of this torque coincides with the preceding rotation direction of the rotor 3a described above. Therefore, the worm 4 rotates so as to cancel the differential between the rotor 3a and the sleeve 4a. The worm is allowed to rotate and the piston 6 moves, which is then transmitted to steer the wheels.

The differential between the rotor 3a and sleeve 4a is as follows:
It continues while turning the steering wheel. Also, this differential is
The torsional distortion of the torsion bar 10 is continued. This torsional reaction force is felt by the driver as a steering reaction force of the steering wheel through the steering wheel, and is useful for steering control.

However, the torsional characteristics of the torsion bar do not represent accurate steering reaction forces. The reaction piston operates to compensate for this inaccuracy. As shown in FIG. 4-A, when the handle is turned to the right, the protrusion 3b of the rotor is angularly protruded with respect to the rotor 4 as shown in the figure, so that each reaction piston 30 is attached thereto. and slide it into each hole 31. When the handle is turned to the right, the pressure inside the stepped hole 28 is high and the pressure around the outer circumference of the rotor 4 is relatively low, so the differential pressure acts between the pressure receiving surfaces on both sides of each reaction piston 30. At that stage, this differential pressure is applied to the pressure receiving surface of the power piston 6.
It is the differential pressure that is working, and it is the differential pressure that is working as a power assist. Therefore, this differential pressure acts on each reaction piston in FIG. 4-A to resist the counterclockwise rotation of the rotor projection 3b. However, since this differential pressure is an accurate power assist pressure, it is transmitted to the steering wheel as an accurate reaction force via the rotor 3a and is useful for steering control. The case where the steering wheel is turned to the right has been described above, but when the steering wheel is turned to the left, the exact opposite operation is performed as shown in Figure 4-B. In addition, in Fig. 4-A, the pressure inside the stepped hole 28 (pressurizing chamber 8b) was higher, but in Fig. 4-B.
In the figure, on the contrary, the pressure is higher at the outer periphery of the rotor 4 (pressurizing chamber 8a).

Since the device of the present invention uses the hollow lumen of the worm as a passage to one pressurizing chamber 8b,
It is not necessary to provide a reaction chamber, that is, a communication path between the hole 31 and the pressurizing chamber in the wall of the housing 1. Also, since the worm 4 is provided with a reaction force chamber, that is, a hole 31,
Due to the design of the reaction force chamber, it is possible to provide a relatively large pressure receiving area of the reaction force chamber, and a large reaction force torque can be obtained. Further, since the reaction torque is transmitted from the reaction piston 30 to the protrusion 3b by a link mechanism using the pin and the elongated hole 30a, the structure is simple and the operation is smooth and reliable.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of the power steering device of the present invention, Fig. 2 is a sectional view taken along the line - - of Figs.
The figure is a partially enlarged longitudinal cross-sectional view, and Figure 4 is the same as Figures 1 and 3.
The cross section taken along the line ``--'', Figure 4-A, and Figure 4-B are views similar to Figure 4 for illustrating the operation. 1...housing, 2...cover, 3...input shaft, 3
a... Rotor, 4... Worm, 4a... Worm end, 6... Power piston, 6'... Rack, 7'... Sector gear, 7... Sector shaft.

Claims (1)

[Claims] 1 Supports a rotor that rotates integrally with the steering handle, an end of a worm that cooperates with the worm to constitute a rotary throttle valve mechanism, a power piston that engages with the worm, and a sector gear that engages with the power piston via a rack. In a power steering device comprising a sector shaft that is fixedly fixed and interlocked with a steering wheel, the worm is formed hollow, and the inside of this hollow portion is connected to one of the pressurizing chambers on both sides of the power piston. A reaction force device consisting of a cylinder and a reaction piston that operates perpendicularly to the direction of the rotational axis of the worm is installed on the wall of this hollow space, and one side of the reaction piston receives pressure. The inside of the worm hollow part is exposed to the liquid pressure of the one pressurizing chamber, the opposite pressure receiving surface is exposed to the outer circumferential space of the hollow part, and this outer circumferential space is communicated with the pressurizing chamber opposite to the pressurizing chamber. , the reaction piston is operatively connected to the rotor by a connection consisting of a pin and an elongated hole in which the pin engages, and the pressure receiving operation of the reaction piston acts to resist rotation of the rotor. ,
A power steering device for an automobile, characterized in that the throttle valve mechanism is disposed on a hydraulic circuit that communicates an inlet of a discharge flow from a hydraulic pressure source pump with both pressurizing chambers.