JPS6143655Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a booster type power steering cylinder.

Conventionally, the valve spool installed in such a cylinder has a spring mechanism for returning to neutrality attached to the sliding spool, and a sleeve fixed to the valve casing, as described in Japanese Patent Publication No. 46-28609. A shifter sleeve that is slidably fitted inside is interlocked with the sliding spool, and one end of the operating member connected to the pitman arm is held, ball-supported, and held by a two-part member inside the shifter sleeve. The cylinder was configured to expand and contract as the Pitman arm was operated, and when the cylinder expanded and contracted by a predetermined amount, the sliding spool returned to the neutral position. Not only does it take time to assemble the spring mechanism because both the spring mechanism for returning to neutral must be installed at the same time, but when replacing or adjusting the spring, it is necessary to disassemble the spool operating part, which consists of the shifter sleeve, etc. It was necessary to remove it. Furthermore, the spherical end of the operating member connected to the pitman arm must be held and ball-supported by a two-part member inside the shifter sleeve, which complicates the structure of the spool operating part, and also prevents the spherical end from wobbling. In order to clamp the spool, a spring member for biasing one of the two halves in the clamping direction is also required, making the structure of the spool operation part even more complicated.

In view of the above-mentioned circumstances, the present invention aims to simplify the structure of the spool operating section.

The characteristic structure of the booster-type power steering cylinder according to the present invention to achieve the above object is that a sleeve into which a large-diameter boss is slidably fitted is fixed to a valve casing, and one end side of the large-diameter boss and the valve casing are fixed to each other. The internal sliding spool is integrated with the internal sliding spool, and a spring mechanism is provided on the other end of the large diameter boss to return the sliding spool to neutral, and a connecting pin is inserted into the large diameter boss, and the connecting pin and the Pittman arm This structure provides the following effects.

In other words, the spring mechanism for returning to neutrality can be installed and removed by working from the opening on the opposite side of the sleeve from the side that is fixed to the valve casing, so the spring mechanism can be installed before or after assembling the spool to the valve casing. This makes it easier to assemble, and it also makes it possible to replace or adjust only the spring mechanism without disassembling the entire spool operating section structure, which is advantageous for maintenance.

Furthermore, a connecting pin was inserted into the sliding spool, and the connecting pin and the Pittman arm were interlocked, so that the spherical end of the operating member could be held between the two split members.
The structure of the spool operation part can be simplified compared to the conventional ball-supported structure, and the biasing spring attached to the two-split member is no longer necessary.

Embodiments of the present invention will be described below based on illustrative drawings.

Fig. 1 shows an agricultural tractor equipped with a booster type power steering device, in which the tip of the pitman arm 3 of the steering gear box 2 attached to the machine 1 is connected to the booster type power steering device with the rear end connected to the machine 1 by a ball fulcrum. It is connected to a valve operation sleeve 5 of a steering cylinder 4, and the front end of this cylinder 4 is connected to a knuckle arm 7 of a front wheel 6 or a drag link 8.

FIG. 2 shows a cross section of the cylinder 4, in which a valve casing 10 is screwed to the front part of the cylinder body 9 in which the piston 21 is installed, and a sleeve in which the operating sleeve 5 is mounted on the front part of the casing 10. 11 is fixed.

A cage valve 12 is inserted into the inside of the valve casing 10 and fixed with a nut 13, and a spool 14 is inserted into the cage valve 12 from the front. The front part of this spool 14 protrudes into the sleeve 11, and a connecting pin 15 is inserted between the large-diameter boss part 14a that fits inside the sleeve 11 and the operation sleeve 5 that fits outside the sleeve 11, Further, the pitman arm 3 is connected to this pin 15. Note that long holes 16, 16 are formed in the sleeve 11 to allow the pin 15 to move as the operating sleeve 5 moves back and forth.

Further, a spring receiving boss 14b for sheathing one coil spring 17 is provided on the protruding portion of the spool 14 in the sleeve 11, and this spring 17
A pair of spring receiving washers 18, 18 provided at the front and rear of the sleeve 11 are supported by stopper rings 19, 19 which are engaged and fixed to the inner circumferential surface of the sleeve 11 to constitute a spring mechanism for returning the spool 14 to neutral. , double washer 1
The spool 14 is set to be held at a neutral position with the spools 8 and 18 abutting and supported by stoppers 19 and 19, respectively. In the figure, P is a pump port, T is a drain port, A and B are output ports, and R is a relief valve.

Next, the operation of this cylinder 4 will be explained.

When the operating handle 20 is turned to the left from the illustrated state, the spool 14 is shifted forward via the operating sleeve 5, the pump port P is communicated with the output port A via the oil passage a on the outer circumference of the spool, and the bottom of the cylinder body 9 is By supplying pressure oil to the side, the piston 2
1 is projected and operated, the entire cylinder 4 is extended and the front wheel 6 is turned to the left, and when the rotation of the steering handle 20 is stopped, the cylinder 4 is extended until the spool 14 returns to neutral and then stopped. Conversely, when the control handle 20 is turned to the right, the spool 14 is shifted rearward, and the pump port P is communicated with the other output port B via the oil passage b on the outer circumference of the spool, and the piston rod side of the cylinder body 9 is connected. By supplying pressure oil to the cylinder 4, the entire cylinder 4 is shortened, and the front wheel 6 is turned to the right until the handle 20 is turned completely.

Furthermore, when the control handle 20 is released, the spool 14 is maintained neutrally by the spring 17.

In addition, at this neutral time, the pressure oil supplied from the pump port P is guided to the oil drain port T through the oil passage C in the spool, and due to the exhaust pressure at this time, a forward thrust force is applied to the spool 14. A pressure-receiving surface S having approximately the same diameter as the spool diameter is also formed at the rear end of the spool 14 to prevent this from acting.

[Brief explanation of the drawing]

The drawings show an embodiment of a booster type power steering cylinder according to the present invention, with FIG. 1 being a schematic plan view of a tractor, and FIG. 2 being a cross-sectional plan view of the cylinder. 3...Pittman arm, 14...Sliding spool, 14a...Large diameter boss, 15...Connecting pin, 1
1... Sleeve, 10... Valve casing, 1
7...Spring.

Claims (1)

[Scope of utility model registration request] A sleeve 11 into which the large-diameter boss 14a is slidably fitted is fixed to the valve casing 10, and one end side of the large-diameter boss 14a and the sliding spool 14 inside the valve casing 10 are integrally configured. A spring mechanism for returning the sliding spool 14 to neutral is provided on the other end side of the large diameter boss 14a, a connecting pin 15 is inserted into the large diameter boss 14a, and the connecting pin 15 and the pitman arm 3 are interlocked and connected. Booster type power steering cylinder.