JPS58166106A - Hydraulic cylinder device - Google Patents

Abstract

PURPOSE:To reduce a shock when a piston is stopped by a method wherein a valve capable of opening and closing a part of a hydraulic hole is arranged at a piston head and the valve is operated to close at least a part of the hydraulic hole before the piston is abutted against a cylinder end surface. CONSTITUTION:At the head part of a piston 2 is arranged a valve 12 depressed in such a direction as being projected from the head part of the piston 2. Thereby, the valve 12 closes the hydraulic hole 7 before the piston 2 is struck against the end surface of the cylinder 4, a pressure in a pressure chamber 5 between the cylinder 4 and the piston 2 is increased and the piston 2 is deccelerated at a position where the force applied to the piston 2 and the pressure in the pressure chamber 5 are balanced, resulting in that the shock generated when stopped can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic cylinder, and is effective for use in, for example, a fuel injection device for a diesel engine.

A conventional hydraulic cylinder 1 of this type was constructed as shown in Fig. 1, but the hydraulic cylinder 1 was constructed so that the low-pressure piston 2 moved until it came into contact with the cylinder head 4a, which caused the engine to rotate at high speed. When the low-pressure piston 2 moves quickly, there is a problem in that the low-pressure piston causes damping when it collides with the cylinder head 4a. This damping has the disadvantage that the high-pressure piston 3 is pushed again, resulting in injection, and that the repeated impact force of the low-pressure piston 2 on the cylinder 4 causes fatigue damage to the cylinder head 4a.

The present invention has been devised in view of the above points, and includes a pulp that can block at least a portion of the hydraulic hole on the piston head or the cylinder end surface, so that the piston hits the cylinder end surface before it collides with the cylinder end surface. By blocking at least a portion of the hydraulic hole with the pulp, the pressure in the pressure chamber between the cylinder and the piston is increased, and the piston is decelerated or stopped at a position where the force applied to the piston and the pressure in the pressure chamber are balanced, and the pressure applied to the cylinder is increased. Reduces the impact force and makes the piston smoother (
2) The purpose is to enable safe driving.

An embodiment of the present invention will be described below with reference to FIG.

The hydraulic cylinder device 1 is composed of a low-pressure piston 2, a high-pressure piston 3, and a cylinder 4, and forms a low-pressure chamber 5 between the end face (cylinder head 4a) of the low-pressure piston 2 and the cylinder 4. A high pressure chamber 6 is formed between the end face and the end face.

A low pressure hydraulic hole 7 is provided in the end face of the cylinder 4 that forms the low pressure chamber 5.
A high-pressure hydraulic hole 8 is provided in the end face of the cylinder 4 forming the high-pressure chamber 6. And high pressure hydraulic hole 8
is branched in the middle; one side communicates with the injection nozzle 9 and the other side communicates with the fuel inlet 11 via the check valve 10.

The head of the low-pressure piston 2 is provided with a pulp 12 that can close the low-pressure hydraulic hole 7. This pulp 12 is pressed by a spring 13 in the direction of protruding from the head of the low pressure piston 2. Of course, the pulp 12 is stopped by the stoppers 14A and 14B so that it does not come off the low pressure piston 2, and therefore, the stroke (3) loaf of the pulp 12 protruding from the low pressure piston 2 is determined. Note that the stopper 14B has a thread cut at its tip and is screwed and fixed to the pulp 12. After the pulp 12, spring 13, and stoppers 14A and 14B are assembled into the holder 15, they are driven into the low-pressure piston 2 as one piece and fixed therein.

The holder 15 is provided with a groove 16, and the spring chamber 17 and the low pressure chamber 5 are electrically connected through the groove 16.

The operation of the hydraulic cylinder configured as above will be explained.

At the time of fuel injection, first the pressure is relatively low (for example, 120 to 1
70 atmospheres) of fuel is fed under pressure to the low pressure chamber 5 from the low pressure hydraulic hole 7, and the low pressure piston 2 begins to move. As a result of the low-pressure piston 2 pressing against the high-pressure piston 3, high pressure is generated in the high-pressure chamber 6, and this pressure reaches the set pressure (for example, 100
When the pressure exceeds 0 atmospheric pressure), fuel is injected from the injection nozzle 9.

When the fuel injection is completed, the oil pressure in the low pressure chamber 5 is removed, and at the same time, the fuel to be injected next time is pumped into the high pressure chamber 6 from the fuel supply 11 via the chinic valve.

(4) Therefore, the pressure of the fuel introduced into the high pressure chamber 6 pushes the high pressure piston 3 and the low pressure piston 2 back to the left.

At this time, when the low pressure piston 2 approaches the end face of the cylinder 4, the pulp 12 provided on the head of the low pressure piston 2 first blocks the low pressure hydraulic hole 7 provided on the end face of the cylinder 4. When this happens, the fuel in the low pressure chamber 5 cannot escape, so the leftward movement of the low pressure piston 2 body is gradually decelerated.

That is, the pressure within the low pressure chamber 5 increases as the low pressure piston 2 moves, and the low pressure piston 2 stops at a position balanced with the force pushing the low pressure piston 2 by the high pressure piston 3.

Therefore, the low-pressure piston 2 can be gradually decelerated and can operate smoothly without colliding with the end face of the cylinder 4. As a result, the injection nozzle 9 will not perform abnormal injection, and the low-pressure piston 2 will not collide with the end face of the cylinder 4 and damage the hydraulic cylinder 1.

In the above-mentioned embodiment, the low pressure hydraulic hole 7 was completely blocked by the pulp 12 (5) to prevent the low pressure piston 2 from colliding with the end face of the cylinder 4, but the position of the low pressure piston 2 was changed to If you want to pull it back to the end face, it is advisable to provide a diaphragm 18 as shown in FIG. In FIG. 3, a throttle 18 is formed in the pulp 12 so that a narrow throttle is formed between the low pressure chamber 5 and the low pressure hydraulic hole 7 when the pulp 12 closes the low pressure hydraulic hole 7, and the pulp 12 is inserted into the cylinder 4. After closing the end face of the cylinder, the low pressure piston 2 is moved to the end face of the cylinder while decelerating its speed.

Further, in the above embodiment, the pulp 12 was provided at the head of the low pressure piston 2, but the pulp 12 was provided at the end surface of the cylinder 4.
Even if 2 is provided, the same effect can be obtained.

As explained above, in the present invention, pulp capable of blocking at least part of the hydraulic holes is provided in one part of the screw thread or the end face of the cylinder, so that when the piston moves, the pulp is By reducing the number of holes (and partially blocking them, the pressure in the pressure chamber between the cylinder and piston increases6), the piston is decelerated or stopped at a position where the force applied to the piston and the pressure in the pressure chamber are balanced. It is possible to reduce the impact force on the cylinder.

Therefore, it has the excellent effect of avoiding damping of the piston due to the reaction force generated when the piston collides with the cylinder, preventing abnormal injection from the injection nozzle, and enabling smooth operation. ing.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a conventional configuration, FIG. 2 is a cross-sectional view showing the configuration of one embodiment of the device of the present invention, and FIG. 3 is a cross-sectional view showing another example of the device of the present invention. 1...Hydraulic cylinder, 2...Low pressure piston, 3...
・High pressure piston, 4... cylinder, 5... low pressure chamber,
7...Low pressure hydraulic hole, 12...Pulp. Representative Patent Attorney Takashi Okabe (7) Procedural amendment (method) 1982 Patent No. 48406 2 Name of the invention Hydraulic cylinder device 3 Person making the amendment Relationship to the case Patent applicant Iwatani, Shimohazuno-cho, Nishio City, Aichi Prefecture Address 14 (469) Japan Auto Parts Research Institute Co., Ltd. Representative Shogo Mita 4th Director Mr. 1-1-5 Showa-cho, Kariya-shi, Aichi Prefecture 448 The date and explanation of the amendment order has been corrected.

Claims (1)

[Claims] (1) A hydraulic cylinder device comprising a cylinder and a piston that reciprocates within the cylinder by hydraulic pressure, and in which a hydraulic hole for introducing and discharging fluid is formed in the end face of the cylinder, in which the piston head or the cylinder end face & : Providing a pulp capable of blocking at least a portion of the hydraulic hole,
The hydraulic cylinder gap ↑ is characterized in that the pulp blocks at least a portion of the hydraulic hole before the piston comes into contact with the cylinder end surface. (2. The hydraulic cylinder device according to claim 1, wherein when the pulp closes the hydraulic hole, a restriction is formed between the cylinder end face and the hydraulic hole. .