JPH0115924Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a cushion mechanism for a hydraulic cylinder, and its purpose is to simplify the structure, facilitate manufacturing, and reduce costs.

An example of a conventional cushion mechanism of this type is shown in FIG. 1, in which 1 is a piston rod, 2 is a piston, 3 is a cylinder, 4 is a cylinder head, and 5 is a valve body that slides onto the piston rod 1 through a bush 6. The piston 2 is fitted freely, and the spring 7
A certain distance is set between them. 8 is a pressure chamber in the cylinder 3, 9 is a main port provided in the cylinder head 4, 10 is a bypass passage, and as shown in the second figure, a large number of pores 11 are formed diagonally in stages on the side wall of the valve body 5. During the compression stroke of the piston 2, the bushes 6 successively close one of the pores 11 to control the flow rate.

In such conventional products, the pores 1 of the valve body 5
The process of sequentially arranging a large number of bushes 6 is time-consuming, and the size increases in the outer diameter direction by the amount of the bushes 6 to be installed. Therefore, there is a problem in that it is difficult to construct a valve with a small gap between the piston rod 1 and the cylinder 3, and for example, if the valve body 5 becomes larger in the outer diameter direction, the bypass passage 10 will be blocked.

The present invention was constructed in order to eliminate the drawbacks of the conventional products as described above, and according to the present invention,
An annular recess 1b is bored in the piston rod 1, and the annular recess 1b is communicated with the pressure chamber 8 through the throttle passage 5a of the valve body 5, and connected to the main port 9 through the communication passage provided in the valve body 5. The throttle passage 5a communicates with the shoulder 1 of the annular recess 1b during the cushioning stroke.
An example of the implementation of the present invention will be described below with reference to FIG. 3 of the drawings.

FIG. 3 is an enlarged sectional view of the main parts of an embodiment of the cushion mechanism based on the present invention, in which parts similar to those of the conventional one are designated by the same reference numerals. Therefore, the difference from the conventional product described above lies mainly in the structure of the valve body 5, in which the valve body 5 is provided with a throttle passage 5a, and as will be described later, the shoulder portion of the piston rod 1
a, and a bypass passage 5b is provided. piston rod 1
An annular recess 1b is provided at a position where the valve body 5 is always held in the expanded state of the spring 7, and the valve body 5 is made to straddle the recess 1b.

In the cushion mechanism of the present invention constructed as described above, when the valve body 5 comes into contact with the cylinder head 4 during the cushion stroke and the main port 9 is closed, oil flows through the throttle passage 5a, the annular recess 1b, and the bypass passage 5b. will be flowing. Furthermore, as the piston 2 moves in the compression direction, its shoulder portion 1a gradually closes the throttle passage 5a, controls the flow rate, and performs a cushioning action, and eventually closes the throttle passage 5a. It becomes a blockage.

Next, when the piston 2 moves back, the shoulder 1a first opens the throttle passage 5a, restores the relative position between the annular recess 1b and the valve body 5 (as shown in the third figure), and then moves the valve body integrally with the piston rod 1. 5 is also movable, and this type of cushion mechanism is used, for example, in a medium-low pressure cushion mechanism of a power shovel.

It goes without saying that after the cylinder head 4 and the valve body 5 are released from contact and the piston 2 moves to the right, the valve body 5 is moved to the left by the spring 7.

As described above, according to the present invention, the throttle passage 5a and the bypass passage 5b are provided in the valve body 5, so there is no need to provide a large number of pores 11 as in the conventional product, and there is no need to provide a bypass passage on the cylinder head 4 side. Since the bushing 6 is not required and only the annular recess 1b is provided in the piston rod 1, it is easy to manufacture even a pressure chamber 8 with a small capacity. has advantages,
The practical benefits are extremely significant.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway vertical side view showing an example of a conventional hydraulic cylinder, Fig. 2 is an enlarged side view showing the main parts of the valve body, and Fig. 3 is a main part of the cushion mechanism of the hydraulic cylinder based on the present invention. It is a partially cutaway enlarged sectional view showing the section. 1-piston rod, 1a-shoulder, 1b-annular recess, 2-piston, 3-cylinder, 4-cylinder head, 5-valve body, 5a-throttle passage, 5b-bypass passage, 6-bush, 7-spring, 8
~Pressure chamber, 9~main port, 10~bypass passage.

Claims (1)

[Scope of utility model registration request] A valve body that is slidably fitted onto the piston rod and has a certain gap between it and the piston via a spring is arranged in parallel with the piston, and the flow rate of oil is controlled via the valve body at the end of the stroke of the piston. In the hydraulic cylinder, the valve body is provided with a throttle passage that opens laterally and communicates with the cylinder pressure chamber, and the piston rod is provided with an annular recess that communicates with the throttle passage. A cushion mechanism for a hydraulic cylinder, characterized in that a valve body is provided with a communicating passage with a main port, and the throttle passage is gradually closed by a shoulder of an annular recess during the cushion stroke.