JPH04102731A - Dashpot - Google Patents

Abstract

PURPOSE:To obtain a dashpot which possesses the easiness in assembly and drastically prevents the abrasion between the controlled equipment and a piston rod by installing a cap made of synthetic resin for the contact with the controlled equipment at the top edge of a piston rod. CONSTITUTION:When a cap 11 made of synthetic resin is installed at the top end of a piston rod 4, the abrasion generated at the contact part in the contact between the controlled equipment which is commonly made of metal and the piston rod 4 is reduced, and the operation starting point is kept constant, and the stable operation state is always secured. Further, since an annular groove 10 for fixing the cap 11 is formed at a small diameter part 9, the trouble that packing a 14 is caught and broken by the annular groove 10 or the shaft seal function is deteriorated is avoided, and the superior airtight state is maintained, when the packing 14 is fitted from the top edge into the piston rod 4.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a dashpot used to reduce the operating speed of controlled equipment and prevent sudden changes in force or position.

(Prior art) There are two types of dashpots: pneumatic type and liquid type. It is well known that a diaphragm is generally used as a shock absorbing member for a controlled device, and a diaphragm or a piston is used for a liquid type.

Among these, the pneumatic type is, for example,
As disclosed in Publication No. 9 and Japanese Patent Publication No. 59-30898, it is widely used for controlling the closing speed of intake throttle valves in automobile engines because it uses atmospheric air and can be easily installed. It is unavoidable that the diameter is large, and if the stroke is increased, the diameter becomes even larger, which not only limits the installation location, but also has the disadvantage that the initial distortion of the diaphragm causes large variations in the starting point of operation. be. In addition, in liquid types, whether using a diaphragm or a piston, the volume of the sealed liquid does not change much due to the influence of temperature, but if the controlled device is away from the piston rod, the piston position will remain constant. However, the disadvantage is that the starting point of the operation is unstable and it is difficult to perform constant control. Furthermore, when a diaphragm is used in a liquid type, a large amount of liquid is sealed in the diaphragm, resulting in a large weight, and bubbles are generated at high temperatures, which tends to change the characteristics, making it impractical.

(Problems to be Solved by the Invention) The problems to be solved by the present invention are that conventional dashpots have a large diameter, which limits the installation location, and the operating characteristics are unstable and tend to lack reliability. .

That is, the present invention is a dashpot with a compact configuration that is small in diameter, is less subject to restrictions on installation location, and has stable operating characteristics, and is particularly easy to assemble and prevents wear between the controlled equipment and the piston rod. The aim is to provide an excellent dashpot.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a cylinder tube having a partition wall that divides the interior into two spaces, front and rear, and a cylinder tube that extends vertically through the front space and penetrates the partition wall. A piston rod inserted into the space, a piston attached to the piston rod and dividing the rear space into a first chamber on the partition wall side and a second chamber on the opposite side, and pushing the piston toward the partition wall. A return spring, a communication passage and a throttle passage that communicate the first chamber and the second chamber, a reverse valve that opens and closes the communication passage to reduce the movement speed of the piston toward the second chamber, and a space in front of the In addition, a synthetic resin cap was attached to the tip of the piston rod so that the controlled equipment came into contact with the piston rod.

Incidentally, it is preferable that the tip of the piston rod be a diameter part having an annular groove, and the camp should be engaged with the annular groove and attached to the small diameter part.

(Function) In the non-operating state, the piston is pushed back by the spring to a position where movement is prevented by the partition wall, and the starting point of operation remains constant. When the controlled device pushes the piston rod, the check valve closes and reduces the operating speed by restricting fluid movement from the second chamber to the first chamber. Furthermore, the fluid in the first and second chambers is sealed without leaking by the packing placed across the partition wall, and the piston rod is supported by the partition wall and reciprocates linearly.

The controlled device contacts the synthetic resin cap and pushes the piston rod, and the cap is attached to the piston rod after the packing is assembled.

(Example) The present invention will be described in detail with reference to the drawings.

The cylinder tube 1 has a partition wall 2 in the center thereof, and the inside of the cylinder tube 1 is partitioned into two front and rear spaces by the partition wall 2, and the cylinder tube 1 has both ends open. A piston rod 4 is inserted through the through hole 3, and this piston rod 4 is fitted into the guide hole 6 of the guide member 5 fixed to the open end, and the through hole 3 and the guide hole 6 form a straight line. It is supported for reciprocating motion. The guide member 5 is made of hard synthetic resin, and includes a flange portion 7 that is fitted into a stepped portion 1a at the end of the cylinder tube 1 and held and fixed by an outer caulking portion 1b, and a collar portion 8 that extends outward. It has

Further, a small diameter portion 9 having an annular groove 10 is formed at the tip of the piston rod 4 protruding from the cylinder tube 1.
A hard synthetic resin cap 11 having a diameter larger than that of the piston rod 4 is attached to the small diameter portion 9 by engaging an annular protrusion 11a on the inner circumferential surface with an annular groove 10, and is attached to the small diameter portion 9 of the piston rod 4. 1 is a bellows-shaped dust cover 1 whose both ends are fitted and fixed to the tip of the piston rod 4 and the small diameter portion 8a of the collar portion 8.
It is covered by 2.

In the space in front of the cylinder tube 1, that is, the inside between the partition wall 2 and the guide member 5, a packing chamber 13 with a small diameter on the partition wall 2 side is formed by a stepped portion 1c. The collar portion 16 of the spring receiver 15, which is loosely fitted to the piston rod 4, is inserted and is slightly separated from the end surface of the packing 14. The flange portion 17 of the spring receiver 15 is located at the large diameter portion on the side of the guide member 5, and is pushed in the direction of contact with the stepped portion 1c by a push spring 18 consisting of a compression coil spring inserted between the flange portions 7 of the guide member 5. I am receiving power.

The rear open end of the cylinder tube 1 is hermetically sealed by a plug 20 having an O-ring 19 that engages with the stepped portion 1d and is pressed and fixed by the outer caulking portion 1e. The space behind the cylinder tube 1, that is, the partition wall 2 and the plug 2o
The inside between the two has a uniform diameter, and is partitioned into a first chamber 21 on the partition wall 2 side and a second chamber 22 on the plug 20 side by a piston 23 attached to a piston rod 4 protruding from this part.

That is, a retaining ring 24 is attached and fixed to a portion of the piston rod 4 that protrudes 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 attached to the piston rod 4 on the tip side thereof. It is fitted. The piston 23 is made of synthetic rubber, synthetic resin, or leather;
A disc-shaped main body 23a sandwiched between the piston stopper 25 and the piston retainer 26 and the second chamber 2 from its outer periphery
It is formed from an elastic cylindrical peripheral edge part 23b which becomes larger in diameter toward 2 and is inscribed in the cylinder tube 11, and the cylindrical peripheral edge part 23b is inscribed in the cylinder tube 1 to such an extent that it can be rotated by hand. The piston retainer 26 is made of hard synthetic resin, and a metal sleeve 27 is embedded and fixed by insert molding on the inner peripheral surface of the tip portion that is fitted into the piston rod 4, and this sleeve 27 is press-fitted into the piston rod 4. By doing so, the piston stopper 25 and the piston 2
3 is pressed and fixed to a retaining ring 24.

The piston retainer 26 consists of a flange portion 28 overlaid on the main body portion 231 of the piston 23, a cylindrical portion 29 extending rearward of the piston rod 4, and a bottom portion 30 at the rear end, and has a fluid inlet/outlet 31 in the bottom portion 30. The piston rod 4 has a communication passage 32 that is open to the rear end surface and the outer circumferential surface facing the first chamber 21, and the communication passage 32 is connected to the piston rod 4 in a small diameter portion behind the press-fitting point of the sleeve 27. It has a throttle passage 33 consisting of an orifice communicating with a valve chamber 34 surrounded by a piston retainer 26. Further, a valve body 35 made of a ball that opens and closes the communication passage 32 is inserted into the valve chamber 34, and a valve seat 3 at the end of the fluid inlet/outlet 31 and the communication passage 32 is inserted.
6, the valve chamber 84 and the valve body 35 constitute the check valve 37.

Furthermore, a return spring 38 made of a compression coil spring is press-fitted between the flange portion 28 and the plug 20.

Incidentally, a screw 39 for attachment is provided on the outer peripheral surface of the cylinder tube 1.

In this embodiment configured in this manner, the piston stopper 25 hits the partition wall 2 due to the spring load of the return spring 38 in the non-operating state as shown in FIG. 1, thereby minimizing the volume of the first chamber 21. The piston 23 moves to the position, and the piston rod 4
The tip of the cylinder protrudes the most from the cylinder tube 1.

When the controlled device comes into contact with the cap 11 and moves the piston rod 4 backward, the first chamber 21 expands and the second chamber 22 contracts, increasing its internal pressure, so the valve body 35 closes the communication path 32. The fluid in the second chamber 22 is transferred from the throttle passage 33 to the communication passage 3.
2 and is gradually introduced into the first chamber 21 to reduce the operating speed of the controlled equipment. When the controlled device leaves, the return spring 3
The piston 23 and the piston rod 4 move forward under the spring load of 8, and in order to contract the first chamber 21 and increase its internal pressure, the valve body 35 opens the communication passage 32, and the fluid in the first chamber 21 flows into the second chamber 22. Return the piston rod 4 to the inoperative position by moving it without resistance.

The present invention is characterized in that a synthetic resin cap is attached to the tip of the piston rod, thereby reducing the wear that generally occurs at the contact portion when the controlled device made of metal and the piston rod come into contact with each other. To prevent an operation starting point from being deviated and to always make the operation stable and constant.

Further, in the dashpot having the configuration of the embodiment, for example, the packing 14, the spring receiver 15, and the push spring 1B are inserted into the front space to fix the guide member 5, and the piston stopper 25,
Although it is assembled by inserting the piston rod 4 equipped with the piston 23 and the piston retainer 26 into the cylinder tube 1 from the open end of the rear space, the packing 14 can also be fitted into the piston rod 4 from the tip from the tip. By forming the annular groove 10 for fixing the cap 11 in the small diameter portion 9, it is possible to avoid the inconvenience of the packing 14 being caught in the annular groove 10 or being damaged thereby, impairing the shaft sealing function. Maintain an airtight condition.

According to the configuration of this embodiment, first, 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 increases, or when the spring of the return spring 38 When the pressure in the first chamber 21 increases due to the load, the packing 14 moves until it comes into contact with the spring receiver 15, and further presses the spring 1.
8 can be compressed and moved to absorb the pressure increase, and the pressure resistance and airtightness of the packing 14 are not impaired.

Second, by fitting the piston stopper 25, piston 23, and piston retainer 26 as separate parts to the piston rod 4, the piston rod 4 can be made smaller in diameter, and since the piston stopper 25 is in contact with the partition wall 2, the piston The actuation starting point of the rod 4 can be kept constant, and since the piston 23 is inscribed in the cylinder tube 1 so that it can be rotated by hand, the piston is sometimes compressed and deformed during assembly, making it difficult to change the characteristics. It has the advantage that it can be confirmed by turning the rod 4.

Thirdly, since the piston rod 4 and the piston retainer 26 form a valve chamber 34 containing a valve body 35, the check valve 3
7 has a compact configuration, especially the piston retainer 2.
6 is made of synthetic resin, which has the advantage of being lightweight.

(Effects of the Invention) Since the dashpot of the present invention has a cylinder-piston type, it has a small diameter and is less subject to restrictions on installation location. In addition, the movement of the piston, which is a buffer member, is prevented by the partition wall, and the packing for shaft sealing is placed on the opposite side of the piston, sandwiching the partition wall, so that the piston is held at a fixed position by the partition wall when not in operation. The operation starting point does not change. Moreover, even if the fluid is liquid, the amount of sealed liquid is small, so there is almost no bubble generation at high temperatures, so there is little concern that the characteristics will fluctuate, and furthermore, the piston rod is supported by the partition wall, so it operates stably. .

In particular, according to the present invention, the synthetic resin cap at the tip of the piston rod not only reduces wear and is highly reliable in stabilizing operating characteristics, but also has a small diameter cap attachment point, making it easy to hook the packing during assembly. It is possible to maintain a good airtight condition without worrying about damage.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view showing an embodiment of the present invention, and FIG.
An enlarged partial view of the figure, FIG. 3 is an exploded view of different parts of FIG. 22...Second chamber, 23...Piston,
32...Communication path, 33...Check valve, 3
8...Return spring, 7s5

Claims (1)

[Scope of Claims] 1. A cylinder tube having a partition wall that divides the interior into two front and rear spaces, and a piston rod that traverses the front space, penetrates the partition wall, and is inserted into the rear space. a piston attached to the piston rod and dividing the rear space into a first chamber on the partition wall side and a second chamber on the opposite side; a return spring that pushes the piston toward the partition wall; A communication passage and a throttle passage that communicate the first chamber and the second chamber, a check valve that opens and closes the communication passage to reduce the movement speed of the piston toward the second chamber, and is installed in the space in front of the chamber. and packing for keeping the rear space airtight,
The dashpot is characterized in that the piston rod has a cap made of synthetic resin attached to the tip of the piston rod so as to be in contact with a controlled device. 2. The dashpot according to claim 1, wherein a small diameter portion having an annular groove is formed at the tip of the piston rod, and a cap is attached to the small diameter portion by engaging with the annular groove.