JPS6221660B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power steering device for a vehicle such as an automobile.

As this type of power steering device, a rack rod that is linked to the steering wheels is supported in a steering gear box.
A power cylinder capable of hydraulically driving the rack rod and a control valve for controlling the operation of the power cylinder connected to the steering gear box are already known for use in automobiles.

However, in this device, since the pair of output ports of the control valve and the left and right oil chambers of the power cylinder are connected by two conduits, these conduits and their attachment parts are necessary. It has the disadvantages of a large number of parts and a large number of assembly steps.

The present invention has been proposed in view of the above, and it forms an oil passage inside the device that connects the oil chamber of the power cylinder and the output port of the control valve, thereby omitting the conduit, thereby creating a compact design with fewer parts and fewer assembly steps. The purpose of the present invention is to provide a power steering device.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. Reference numeral 1 denotes a steering gear box fixed to a vehicle body (not shown), and a pinion extending upwardly. The shaft 4 is rotatably supported via ball bearings 5, 5', and the rack 6 of the rack rod 3 and the pinion 7 of the pinion shaft 4 are meshed inside the shaft 4. The pinion shaft 4 is rotated by a steering handle (not shown), and the rack rod 3 is driven by the pinion shaft 4 to move left and right, thereby turning a steering wheel (not shown).

A power cylinder 16 capable of hydraulically driving the rack rod 3 is connected to the left end of the steering gear box 1, and a control valve 9 for controlling the operation of the power cylinder 16 is installed on the lower surface thereof. The control valve 9 has a high pressure port 11 connected to a hydraulic power source 10 such as a hydraulic pump in its valve case;
It has a low pressure port 13 connected to the oil reservoir 12 and a pair of output ports 14 and 15, and when the rack rod 3 is driven from the pinion shaft 4, it senses the driving force and outputs both depending on the magnitude of the driving force. Output port 1
One of the ports 4 and 15 is connected to the high pressure port 11, and the other is connected to the low pressure port 13.

The power cylinder 16 has an outer cylinder 17, an inner cylinder 18 disposed inside the outer cylinder 17, and an operating piston 19 that is fixed to the rack rod 6 and slides into the inner cylinder 18. The inside of the inner cylinder 18 is divided into a first oil chamber 18a that is close to the steering gear box 1 and a second oil chamber 18b that is remote from the first oil chamber 18a.

A mounting flange 21 is provided on the outer periphery of the inner end, that is, the right end, of the outer cylinder 17;
A support tube 26 is fixedly installed at the inner end of each.
This support cylinder 26 has an annular projecting wall 26a having a larger diameter than the inner cylinder 18 on the outer periphery of the intermediate portion. Furthermore, a bearing cap 23 is provided at the outer end of the outer cylinder 17, that is, at the left end.
is fixedly installed, and a flat bearing 24 and a sealing member 25 that slidably support the left end of the rack rod 3 are attached to this.
is installed.

A stepped mounting hole 20 concentric with the rack rod 3 is opened on the left end surface of the steering gear box 1, and a large diameter hole 20a, a medium diameter hole 20b, a small diameter hole 20c and a minimum diameter hole 20d are sequentially formed from the open end side. The inner end of the outer cylinder 17 is fitted into the large diameter hole 20a, and the mounting flange 21 is fixed to the gear box 1 with bolts 22. Further, the projecting wall 26a of the support tube 26 is fitted into the medium diameter hole 20b, and the tip end of the support tube 26 is fitted into the small diameter hole 20c. Further, a support tube 33 fixed to the inner end of the flexible partition tube 34 is fitted into the minimum diameter hole 20d. This partition pipe 34 projects into the inner cylinder 18, and a seal member 36 that closely contacts the outer circumferential surface of the rack rod 3 is installed in a seal housing 35 formed at its outer end.

A cylindrical oil passage _S1 is formed between the inner and outer end cylinders 17 and 18, and the outer end of the inner cylinder 18 communicates with the second oil chamber _18b . A shaped oil passage _S2 is formed between the inner surface of the medium diameter hole 20b and the inner cylinder 18. Medium diameter hole 20b
An annular oil passage 27 is formed between the inner end wall and the projecting wall 26a, and this oil passage 27 connects to the cylindrical oil passage S ₂ through a communication groove 28 on the inner surface of the medium diameter hole 20b at the upper part thereof.
It also communicates with the output port 14 through an oil hole 29 at its lower part.

The first oil chamber 18 is located between the partition pipe 34 and the support tube 33.
A cylindrical oil passage S ₃ continuous to the right end of a is formed, and an annular oil passage S ₄ continuous to the oil passage S ₃ is formed between the inner end wall of the small diameter hole 20 c and the support tube 26 . Also, the small diameter hole 20
A semi-annular oil passage 31 is formed on the inner circumferential surface of the support tube 26 at least half the circumference from the upper part to the lower part. The annular oil passage S ₄
The communication hole 32 is connected to the lower part of the communication hole 32.
It communicates with the output port 15 via.

As mentioned above, in order to secure the annular oil passage _S4 communicating with the first oil chamber 18a between the inner end wall of the small diameter hole 20c and the support tube 26 of the inner cylinder 18, the following steps are performed for the inner cylinder 18. Such an axial positioning means is provided.

That is, an annular recess 38 and a plurality of annularly arranged notches 40, 40, . On the other hand, an annular locking groove 37 is provided on the outer circumferential surface of the support tube 33 of the partition pipe 34 so as to correspond to the annular recess 38 . By engaging with the support tube 33, the axial position of the support tube 33 is regulated. As clearly shown in FIG. 2, the stop ring 39 is formed by bending an annular elastic wire so as to wave in the radial direction, so as not to obstruct the communication between the oil passages S ₃ and S ₄ . , the communication state is further ensured by the notches 40, 40, . . . . Further, this elastic retaining ring 39 allows slight movement of the support tube 33 in the radial direction.

A coil spring 41 that supports the inner cylinder 18 in a floating manner is compressed between the bearing cap 23 of the outer cylinder 17 and the outer end of the inner cylinder 18, and the elastic force of this spring 41 causes the stop ring 39 and the support tube to 26 is maintained, and the end surface of the support tube 33 of the partition pipe 34 is pressed and held against the gear box 1. It is desirable to insert a seat plate 33a into the pressing portion. A gap S ₀ sufficient to establish communication between the second oil chamber 18b of the inner cylinder 18 and the cylindrical oil passage S ₁ in the outer cylinder 17 is provided between adjacent wires of the coil spring 41.

Next, the operation of this embodiment will be explained.

Now, when the operator rotates the pinion shaft 4 clockwise using a steering handle (not shown), the control valve 9 operates to connect one output port 15 to the high pressure port 11.
In addition, the other output port 14 is connected to the low pressure port 13.
Since the pressure oil of the hydraulic source 10 is connected to the output port 15, the oil hole 32, the semi-annular oil passage 31, the communication groove 30, the annular oil passage _S4 , the notches 40, 40..., the cylindrical oil passage _S3 The oil flows sequentially into the first oil chamber 18a of the inner cylinder 18 and presses the operating piston 19 to the left, and the pressing force assists the operator's operating force applied to the rack rod 3 via the pinion shaft 4. The rack rod 3 can be easily moved to the left. in this case,
The oil in the second oil chamber 18b flows through the gap between the coil springs 41.
S ₀ , cylindrical oil passages S ₁ , S ₂ , communication groove 28 , annular oil passage 2
7. The oil passes sequentially through the oil holes 29, flows into the control valve 9 from the output port 14, and then returns to the oil sump 12 via the low pressure port 13. Further, when the pinion shaft 4 is rotated counterclockwise, the operating direction of the control valve 9 is reversed to that described above, and the oil flows in the opposite direction through the respective flow paths, that is, the pressure oil of the hydraulic source 10 is transferred to the second oil chamber 18b. At the same time, the oil in the first oil chamber 18a flows back into the oil sump 12, and the rack rod 3 can be easily moved to the right.

By the way, the first oil chamber 18a or the second oil chamber 18
When oil flows back from b to the oil sump 12, it reaches the annular oil passage 27 or the semi-annular oil passage 31 from the top of each oil chamber through the communication groove 28 or 30 and flows down, so that each oil chamber Air or bubbles remaining or generated in 18a, 18b are removed from each oil chamber 18a, 18b.
The air does not remain in the upper part of the oil, but is quickly discharged to the oil sump 12 along with the refluxing oil, and then floats up from the oil and is discharged to the outside.

If the steering wheel 3 is deflected due to the steering resistance that the steering wheel receives from the road surface while the power cylinder 16 is in operation, and the operating piston 19 is displaced laterally, the inner cylinder 18 will have its outer end bent as described above. Being floatingly supported by the spring 41, it is possible to swing together with the working piston 19, so that the normal concentric relationship between the working piston 19 and the inner cylinder 18 is still maintained, and the working piston 19
can slide smoothly inside the inner cylinder 18. Further, the partition pipe 34 also follows the bending of the rack rod 3 due to its flexibility, so that the sealing member 36 exerts a sufficient sealing effect on the rack rod 3, thereby preventing oil leakage from the first oil chamber 18a. be able to.

As described above, according to the present invention, the power cylinder includes an outer cylinder whose inner end is fixed to the steering gear box, and an outer cylinder which is disposed inside the outer cylinder and whose inner end is fitted and supported by the steering gear box. The working piston is fixed to a rack rod and divides the interior of the inner cylinder into a first oil chamber close to the steering gear box and a second oil chamber spaced apart from the steering gear box. The outer end is floatingly supported in the outer cylinder via a coil spring, and the second oil chamber and the inner side of the outer cylinder are communicated through the gap between the wires of the coil spring, and the pair of output ports of the control valve and the second oil chamber are connected to each other through a gap between the wires of the coil spring. 1 oil chamber and the inside of the outer cylinder are formed in the steering gear box. All of the connecting oil passages are formed inside the device, and there is no need for any conduits as in the past, so the number of parts and assembly steps can be reduced, and a compact power steering device can be obtained. Further, since the second oil chamber and the inner side of the outer cylinder are communicated using a coil spring that supports the inner cylinder in a floating manner, the communication means is simple and assembly is easy. Furthermore, when the long rack rod is deflected due to steering resistance, the floatingly supported inner cylinder is free to move laterally within the outer cylinder while maintaining a proper concentric relationship with the working piston. Therefore, the hydraulic operation of the working piston is always smooth and
It is possible to perform power steering reliably.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional rear view of an embodiment of the device of the present invention;
FIG. 1A is an enlarged sectional view of the area around the inner end support portion of the inner cylinder, and FIGS. 2 and 3 are enlarged sectional views along the line and - of FIG. 1. 1... Steering gear box, 3... Rack rod, 9... Control valve, 14, 15... Output port, 16... Power cylinder, 17... Outer cylinder, 18... Inner cylinder, 18a... No. 1 oil chamber, 18b...2nd oil chamber, 19...operating piston, 29, 27, 2
8, S ₂ ... Output port 14 to outer cylinder 17
32, 31, 30, S ₄ , S _{3 .} . . Oil passages leading from the output port 15 to the first oil chamber 18a.

Claims (1)

[Claims] 1. A rack rod interlocked with a steering wheel is supported on a steering gear box, and a power cylinder capable of hydraulically driving the rack rod and a control valve for controlling the operation of the power cylinder are connected to the steering gear box. In the power cylinder, the power cylinder includes an outer cylinder whose inner end is fixed to the steering gear box, and an inner cylinder which is disposed inside the outer cylinder and whose inner end is fitted and supported by the steering gear box. , an operating piston fixedly attached to the rack rod and dividing the inside of the inner cylinder into a first oil chamber close to the steering gear box and a second oil chamber spaced apart therefrom; The end thereof is floatingly supported in the outer cylinder via a coil spring, and communicates between the second oil chamber and the inner side of the outer cylinder through a gap between the strands of the coil spring, and connects the pair of output ports of the control valve with the inner part of the outer cylinder. A power steering device for a vehicle, characterized in that an oil passage communicating between the first oil chamber and the inside of the outer cylinder is formed in the steering gear box.