JPH027105Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a rack-and-pinion type power steering device, and its purpose is to manufacture it lighter, smaller, and at a lower cost.

Figure 1 shows a first comparative example of a conventional rack-and-pinion type power steering system, in which the gear housing 1, cylinder 2, and valve housing 3 are manufactured separately, and one end of the cylinder 2 is connected to the gear housing 1.
The gear housing 1 and the cylinder 2 were fitted onto the outer periphery of the cylindrical portion 1a, the fitting portion was sealed with the seal member 4, and the gear housing 1 and the cylinder 2 were fixed together with the screws 5, but the number of parts increased and the cost and weight increased. Furthermore, since there are many fastening parts, there is a large variation in assembly accuracy, which has a negative effect on the steering feeling.

Figure 2 shows a second comparative example of a conventional rack-and-pinion power steering system, in which the gear housing 10 and cylinder 11 are integrally molded by aluminum alloy casting. There are problems in that fluid leaks are likely to occur, the wall thickness of the cylinder 11 is thicker than in terms of strength, which is disadvantageous in terms of installation space on the vehicle body, and the cylinder 11 has to be cut, which increases costs. It was hot.

The present invention aims to solve the above problems.

3 and 4 show a first embodiment of the present invention, in which the end of the narrow diameter portion 21a of the cylinder 21 formed from a steel pipe is fitted into the cylindrical portion 20a of the gear housing 20 when the gear housing 20 is cast. Inject. The gear housing 20 is made of an aluminum alloy, and since the coefficient of thermal expansion of the aluminum alloy is larger than that of steel, when the aluminum alloy solidifies, the cylindrical portion 20a strongly tightens the small diameter portion 21a of the cylinder, which is sufficient for practical use. Secure together with strength. A stopper 22 is abutted against the stepped portion 21c of the cylinder large diameter portion 21b, and a sealing member 23 is abutted against the stopper 22 for sealing.
A stopper 24 is fixed to the other end of the large diameter portion 21b, and a seal member 25 is abutted against the stopper 24 for sealing. A rack shaft 26 is slidably inserted into the gear housing 20 and the cylinder 21, and a piston 27 is fixed to the rack shaft 26 at approximately the middle of the large diameter portion 21b of the cylinder.
The large diameter part 21b of the two power cylinder chambers 2
8.29. 30 is easy,
Pipes 31 and 32 connect the power cylinder chambers 28 and 29 and the valve housing 33.
A hole 21a' is formed in the casting part of the narrow diameter part 21a of the cylinder 21, and when the gear housing 20 is cast, an aluminum alloy is inserted into the hole 21a' to prevent it from coming off and rotating. 34 is a pinion shaft.

Note that a groove may be formed instead of the hole 21a'.

Next, the effect will be explained. When the driver operates the steering wheel, the pinion shaft 34 rotates in accordance with the direction of the operation, the pinion teeth and the rack teeth engage and rotate, and the rack shaft 26 moves in the corresponding direction, and the rack shaft 26 is connected to both ends thereof. The steered wheels are steered via a knuckle arm, etc. At the same time, the operating valve in the valve housing 33 operates, selectively supplying and discharging pressure fluid to the power cylinder chamber 28 or 29 through the pipe 31 or 32, causing the pressure fluid to act on the piston 27 and moving the rack shaft 26 in the corresponding direction. Power assist. Pressure fluid acting on the cylinder chambers 28, 29 is sealed by seals 23, 25,
The seals 23, 25 are prevented from moving by stoppers 22, 24. In addition, the power steering system often reaches a high temperature of nearly 100 degrees Celsius while running, but even if the aluminum alloy of the gear housing 20 expands thermally, the aluminum alloy will enter the hole 21a' of the narrow diameter part 21a of the cylinder 21 and become integrated. Since it is curved, the cylinder 21 will not come off or rotate.

Figure 5 shows a second embodiment of the present invention, in which the cylinder 2
There is a protrusion 21 on the outer periphery of the casting part of the small diameter part 21a of 1.
When forming the gear housing 20 and casting the gear housing 20, the cylinder 21 will not come off or rotate because the aluminum alloy is in close contact with its outer periphery.

According to this invention, the gear housing and cylinder are integrated, the piston is fixed to a rack shaft that is arranged so that it can slide through the gear housing and cylinder, and both ends of the cylinder are sealed, so that both sides of the piston are fixed. Two power cylinder chambers are formed, and pressure fluid is selectively supplied to the two power cylinder chambers by an operating valve in the valve housing.
In a rack-and-pinion type power steering device in which power is assisted in the steering direction by discharging the rack via a piston, one end of the cylinder formed from a steel pipe is cast into an aluminum alloy gear housing. Sometimes, the cast cylinder and gear housing are integrated, the cast part of the cylinder is provided with holes, grooves, protrusions, etc. to prevent them from slipping out and rotating, and the cast side of the cylinder is made to have a constant long and thin diameter.
The large diameter part is used as a cylinder chamber, a stopper is abutted against the step part, and a sealing member is abutted against the stopper to seal the cylinder chamber and the rack shaft. are extremely strongly integrated, and even when a large steering power assist force is applied to the cylinder tube as in the case of power steering, the cylinder tube can be prevented from coming off, prevented from rotating, and sealed between the cylinder chamber and the easy shaft using fewer parts. It is lightweight, compact, strong, and requires no cutting, which helps reduce costs.

[Brief explanation of the drawing]

FIG. 1 is a cutaway front view of main parts of a conventional first comparative example;
FIG. 2 is a cutaway front view of the main part of the second conventional comparative example, FIG. 3 is a cutaway front view of the main part of the first embodiment of the present invention, and FIG.
The figure is an enlarged sectional view taken along the line AA in FIG. 3, and FIG. 5 is a view corresponding to FIG. 4 of the second embodiment of the present invention. 20...Gear housing, 21...Cylinder, 21a...Cylinder narrow diameter part, 21a'...
Hole, 21a″...Protrusion, 21b...Cylinder large diameter part, 21c...Cylinder stepped part, 22, 24...
Stotuber, 23, 25... Seal member, 26...
...Rack shaft, 27... Piston, 28, 29...
Power cylinder chamber, 31, 32...pipe, 3
3...Valve housing.

Claims (1)

[Scope of utility model registration request] The gear housing and cylinder are integrated,
The piston is fixed to a rack shaft that is arranged so that it can slide through the gear housing and the cylinder, and both ends of the cylinder are sealed to form two power cylinder chambers on both sides of the piston. In a rack-and-pinion power steering device, the rack is powered in the steering direction via a piston by selectively supplying and discharging pressure fluid to and from two power cylinder chambers using operating valves. When casting an aluminum alloy gear housing, one end of a cylinder formed from a steel pipe is cast, and the cylinder and gear housing are integrated, and holes, grooves, and
The projections, etc. are prevented from falling out and rotated, the casting side of the cylinder has a constant long and narrow diameter, the large diameter part is the cylinder chamber, a stopper is abutted against the stepped part, and a sealing member is abutted against the stopper to form the cylinder chamber. A rack-and-pinion power steering device designed to seal the rack shaft.