JP2899722B2 - Dash pot - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a dashpot used for lowering the operation speed of a controlled device and preventing a sudden change in force or position.

(Prior Art) Dashpots that reduce the operating speed of controlled devices by the throttling effect of fluid to prevent sudden changes in force or position are classified into pneumatic and liquid types. It is well known that a diaphragm is generally used as a buffer member of a controlled device, and a diaphragm or piston is used as a liquid type.

Among them, the pneumatic type can be easily installed using the atmosphere as disclosed in Japanese Utility Model Publication No. 51-39059 and Japanese Patent Publication No. Sho 59-30898, for example. Although it is widely used for valve closing speed control, etc., it is unavoidable that the diameter is quite large, and if the stroke is increased, the diameter becomes even larger, so not only is the installation location restricted, but also the diaphragm has initial distortion. Is disadvantageous in that the variation in the operation start point is large.

On the other hand, the pneumatic type and the liquid type and the piston type have a smaller diameter than the diaphragm, but cannot be sufficiently reduced in size as the check valve is provided on the piston or outside the cylinder.

(Problems to be Solved by the Invention) The problems to be solved by the present invention are that the conventional dashpot is quite large, the installation place is limited, the operating characteristics are unstable, and the reliability is easily lacking. is there.

That is, the present invention is a small-diameter dashpot with a small configuration that is less likely to be restricted by an installation place and has stable operation characteristics. It is designed to be compact.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a cylinder cylinder having a partition wall whose interior is divided into two front and rear spaces; A piston rod inserted into the space, a piston mounted on the piston rod to divide the rear space into a first chamber on the partition wall side and a second chamber on the opposite side, and push the piston back toward the partition wall. A spring, a piston retainer mounted on the piston rod so as to overlap with the second chamber side of the piston, a valve chamber surrounded by the piston rod and the piston retainer and communicated with the second chamber by a fluid port, and provided on the piston rod. A communication passage and a throttle passage that communicate the first chamber and the valve chamber are provided, and a valve body that is inserted into the valve chamber and closes the communication passage when the piston moves toward the second chamber.

The piston retainer is made of synthetic resin, a metal sleeve is fixed to the inner peripheral surface of the tip, and this sleeve is pressed into the piston rod. The throttle passage branches from the communication path to the outer peripheral surface of the piston rod. It is preferable that the opening is opened so as to communicate with the valve chamber.

(Operation) In the inoperative state, the piston is pushed by the return spring to a position where the movement is blocked by the partition wall, and the operation start point is fixed. When the controlled device presses the piston rod, the valve body closes the communication passage and restricts the movement of the fluid moving from the second chamber through the valve chamber to the first chamber, thereby reducing the operation speed.

(Example) An example of the present invention will be described with reference to the drawings. A partition wall 2 having a substantially central partition wall 2 is divided into two front and rear spaces by the partition wall 2, and a front space is longitudinally cut from a front open end to a cylinder cylinder 1 having both ends opened.
The piston rod 4 is inserted into the guide hole 6 of the guide member 5 fixed to the open end, and the piston rod 4 is straightened by the through hole 3 and the guide hole 6. It is supported to reciprocate. The guide member 5 is made of a hard synthetic resin, and has a flange portion 7 fitted into the step portion 1a at the end of the cylinder tube 1 and pressed and fixed by the outer caulking portion 1b, and a collar portion 8 extending outward. have.

A small-diameter portion 9 having an annular groove 10 is formed at the tip of the piston rod 4 protruding from the cylinder cylinder 1, and a hard synthetic resin cap 11 having a larger diameter than the piston rod 4.
Are fitted to the small-diameter portion 9 by engaging with the annular groove 10, and the projecting portion of the piston rod 4 has a bellows-like shape in which both ends are fitted and fixed to the distal end portion of the piston rod 4 and the small-diameter portion 8 a of the collar portion 8. Wrapped by dust cover 12.

Air in front of the cylinder 1, that is, the partition 2 and the guide member 5
The partition wall 2 side is formed as a small-diameter packing chamber 13 by a step portion 1c, and a packing 14 made of a U-ring is press-fitted around the piston rod 4,
The collar portion 16 of the spring receiver 15 loosely fitted to the piston rod 4 is inserted and slightly separated from the end face of the packing 14. Spring support
The flange portion 17 is located at the large-diameter portion on the guide member 5 side, and a force in the direction in which the flange portion 17 comes into contact with the step portion 1c by a pressing spring 18 composed of a compression coil spring inserted between the guide member 5 and the flange portion 7. Is receiving.

The rear open end of the cylinder cylinder 1 is airtightly closed by a plug 20 having an O-ring 19 engaged with a stepped portion 1d and pressed and fixed by an outer caulked portion 1e. The space behind the cylinder 1, that is, the interior between the partition wall 2 and the plug 20 has a uniform diameter, and the piston rod 4
Is partitioned into a first chamber 21 on the partition wall 2 side and a second chamber 22 on the plug 20 side.

That is, a retaining ring 24 is attached and fixed to a portion of the piston rod 4 protruding from the partition wall 2 to the rear space, and a bowl-shaped piston stopper 25, a piston 23, and a piston retainer 26 are sequentially provided on the piston rod 4 on the distal end side. Fitted. piston
23 is made of synthetic rubber, synthetic resin or leather, has a disk-shaped main body 23a sandwiched between a piston stopper 25 and a piston retainer 26, and has a large diameter from the outer peripheral edge toward the second chamber 22 to become the cylinder cylinder 11 And an elastic cylindrical peripheral portion 23b inscribed in the cylinder tube 1. The cylindrical peripheral portion 23b is inscribed in the cylinder tube 1 to the extent that it can be rotated by hand. Piston retainer
26 is made of a hard synthetic resin, and a metal sleeve 27 is embedded and fixed by an insert molding method on the inner peripheral surface of a tip portion fitted to the piston rod 4, and this sleeve 27 is press-fitted into the piston rod 4. As a result, the piston stopper 25 and the piston 23 are pressed and fixed to the retaining ring 24.

The piston retainer 26 has a flange portion 28 superposed on the main body portion 23a of the piston 23 and a cylindrical portion extending rearward of the piston rod 4.
The bottom 30 has a fluid port 31 at the bottom 30. The piston rod 4 has a communication passage 32 opened at the rear end surface and an outer peripheral surface facing the first chamber 21, and has a communication passage 32 at a small diameter portion 4a behind the press-fitting point of the sleeve 27.
And a throttle passage 33 formed of an orifice communicating with a valve chamber 34 surrounded by the piston rod 4 and the piston retainer 26 by opening to the outer peripheral surface. A valve body 35 made of a ball that opens and closes the communication passage 32 is inserted into the valve chamber 34, and the fluid port 31, the valve seat 3 at the end of the communication passage 32
6. The valve chamber 34 and the valve body 35 constitute a check valve 37. It is apparent from the drawing that the check valve 37 is provided on the rear end of the piston rod 4 on the same axis. In addition, the flange
A return spring 38 composed of a compression coil spring is press-fitted between the plug 28 and the plug 20.

A mounting screw 39 is provided on the outer peripheral surface of the cylinder 1.

In this embodiment constructed as described above, the piston stopper 25 urges the partition wall 2 by the spring load of the return spring 38 to minimize the volume of the first chamber 21 in the inoperative state as shown in FIG. The piston 23 moves to the position, and the tip of the piston rod 4 projects the most from the cylinder cylinder 1.

When the controlled device comes into contact with the cap 11 and retreats the piston rod 4, the first chamber 21 expands and the second chamber 22 contracts to increase its internal pressure, so that the valve body 35 closes the communication passage 32 and the second chamber 22 closes. The fluid in the two chambers 22 is gradually introduced from the valve chamber 34 into the first chamber 21 through the communication passage 32 from the throttle passage 33, and the operating speed of the controlled device is reduced. When the controlled device separates, the piston 23 and the piston rod 4 advance by the spring load of the return spring 38, and the valve body 35 opens the communication passage 32 to reduce the first chamber 21 and increase its internal pressure,
The fluid in the first chamber 21 is moved without resistance from the valve chamber 34 to the second chamber 22 to return the piston rod 4 to the inoperative position.

The present invention is characterized in that a check valve 37 is installed concentrically with the piston rod 4 on the second chamber 22 side of the piston 23. Then, the piston retainer 26 is connected to the piston rod 4 and the piston.
Since the valve chamber 34 is formed as a separate part from the piston rod 23 and is fitted to the piston rod 4 and is always in communication with the second chamber 22, it is possible to simplify the cutting work of the piston rod 4 and to downsize the whole. . In this case, the piston retainer 26 may be made of metal. However, according to the present embodiment, the portion made of synthetic resin and press-fitted into the piston rod 4 is made of a metal sleeve 27. In addition, the sleeve 27 is firmly and stably press-fitted and fixed to the piston rod 4.

Also, the throttle passage 33 can be formed very easily by providing the small diameter portion 4a perpendicular to the axis of the piston rod 4 and communicating with the valve chamber 34 by a gap 39 between the small diameter portion 4a and the piston retainer 26. However, as shown in FIG. 3, the entire periphery of the rear end of the piston rod 4 is brought into close contact with the inner peripheral surface of the piston retainer 26 without forming a small-diameter portion, so that the outer peripheral surface of the piston rod 4 extends in the axial direction. The groove passage 40 may be formed by flattening, and the throttle passage 33 may be opened to the groove passage 40 to communicate with the valve chamber 34.

According to the configuration of the present embodiment, first, since the tip of the piston rod 4 has a small diameter portion and a cap 11 made of synthetic resin is mounted, for example, the packing 14 and the like are inserted into the front space, and then the cap 11 is removed. By inserting the unmounted piston rod 4 from the rear space, assembly becomes easy, there is no inconvenience such as the packing 14 being hooked and damaged by the piston rod 4, and the cap 11 comes in contact with the controlled device. There is an advantage that wear is reduced.

Second, when the fluid sealed in the first chamber 21 and the second chamber 22 expands due to a rise in temperature and the overall pressure rises,
Alternatively, when the pressure of the first chamber 21 rises due to the spring load of the return spring 38, the packing 14 moves until it comes into contact with the spring receiver 15, and further compresses and moves the push spring 18 to absorb the pressure rise. 14 The pressure resistance and airtightness are not impaired.

Third, by fitting the piston stopper 25, the piston 23, and the piston retainer 26 to the piston rod 4 as separate components, the diameter and weight of the piston rod 4 can be reduced. The operation start point of the rod 4 can be made constant, and the piston 23 is rotatably inscribed in the cylinder cylinder 1 by hand. There is an advantage that it can be confirmed by turning.

(Effect of the Invention) Since the dashpot of the present invention is of a cylinder / piston type, it has a small diameter and is hardly subject to restrictions on the installation place. In addition, since the movement of the piston, which is the buffer member, is blocked by the partition wall, the piston is kept at a fixed position when it is not operated, and the operation start point does not change. Moreover, even if the fluid is liquid, there is little bubble generation at high temperatures due to the small amount of liquid filling, and there is little concern about fluctuations in characteristics. Further, the piston rod is supported by the partition wall and operates stably. Thus, the stability of the operating characteristics is improved, and the controlled device can be properly controlled.

In particular, according to the present invention, the check valve for controlling the movement of the fluid between the first chamber and the second chamber is formed concentrically with the piston rod by the piston retainer fitted to the rear end of the piston rod. The feature that the size can be sufficiently reduced and the installation place is less restricted is further enhanced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, and FIG.
FIG. 3 is an enlarged partial view, and FIG. 3 is a partial longitudinal sectional view showing a different embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... Cylinder cylinder, 2 ... Partition wall, 4 ... Piston rod, 21 ... First chamber, 22 ... Second chamber, 23 ... Piston, 26 ... Piston retainer, 27 ... Sleeve, 31 ... Fluid port, 32 ... Communication passage, 33…
Throttle passage, 34 ... valve chamber, 35 ... valve body, 37 ... check valve, 38 ... return spring,

Claims (3)

(57) [Claims] 1. A cylinder cylinder having a partition wall dividing the inside into two front and rear spaces, a piston rod vertically penetrating the front space and passing through the partition wall and inserted into the rear space, and the piston A piston mounted on a rod to partition the rear space into a first chamber on the partition wall side and a second chamber on the opposite side, a return spring for pushing the piston toward the partition wall, A piston retainer mounted on the piston rod so as to overlap with the second chamber side, a valve chamber surrounded by the piston rod and the piston retainer and communicating with the second chamber by a fluid port, and provided on the piston rod. A communication passage and a throttle passage communicating the first chamber and the valve chamber, and a valve element inserted into the valve chamber and closing the communication passage when the piston moves toward the second chamber. Dash point characterized by Door. 2. The dash pot according to claim 1, wherein the piston retainer is made of a synthetic resin, and a metal sleeve is fixed to an inner peripheral surface of a tip portion, and the sleeve is press-fitted into the piston rod. 3. The dash pot according to claim 1, wherein the throttle passage branches from the communication passage and opens to the outer peripheral surface of the piston rod to communicate with the valve chamber.