JPH04102730A - Dashpot - Google Patents

Abstract

PURPOSE:To stabilize operation by dividing a cylinder into the front and rear spaces, arranging a piston in the rear space, installing a piston rod penetrating through a partitioning wall, allowing the front and rear parts of the piston to communicate through a partitioning passage having a check valve. CONSTITUTION:A partitioning wall 2 is installed in a cylinder 1, and the inside is divided into two spaces, and a piston rod 4 is inserted, penetrating through the partitioning wall 2, and a piston 23 is installed. The front and rear chambers are allowed to communicate by forming a communication passage 32 on the piston 23, and a check valve 37 having a ball valve body 35 is installed, and a return spring 38 is installed. Since the shift of the piston is suppressed by the partitioning wall and a packing 14 is on the opposite to the piston, the piston is set at a constant position by the partitioning wall when the piston is inoperative, and the operation starting point does not change. Further, since the piston rod is guided by the partitioning wall, operation is stabilized.

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 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 aims to provide a dashpot having a compact configuration, which has a small diameter, is less subject to restrictions on installation location, and has stable operating characteristics.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention first provides a cylinder tube having a partition wall that divides the interior into two spaces, front and rear, and a partition wall that extends vertically through the front space. A piston rod penetrates and is inserted into the rear space, a piston is attached to the piston rod and divides the rear space into a first chamber on the partition wall side and a second chamber on the opposite side, and the piston is inserted into the partition wall side. a return spring that pushes toward the
A communication passage and a restriction passage that communicate the first chamber and the second chamber;
It is equipped with a check valve that opens and closes the communication passage to reduce the speed of movement of the piston toward the second chamber, and a packing installed in the front space to keep the rear space airtight.

Second, in addition to the first configuration, the present invention includes a guide member fixed to the front open end of the cylinder, and the piston rod is supported by the partition wall and the guide member so as to be capable of linear reciprocating movement. Ta.

The guide member is preferably made of synthetic resin and has a flange portion fixed to the cylinder tube by caulking and a collar portion extending outward.

Further, the fluid sealed in the first chamber and the second chamber may be either gas or liquid.

(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 the guide member and reciprocates linearly.

(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. have.

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, and a hard synthetic resin cap 1 having a larger diameter than the piston rod 4 is formed.
1 is engaged with the annular groove 10 and attached to the small diameter portion 9, and the protruding portion of the piston rod 4 has a bellows shape with both ends 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 a dust cover 12.

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 is formed on the partition wall 2 side 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 the flange portion 17 of the guide member 5 is inserted between the flange portions 7 and 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 20
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 portion.

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. Piston stopper 25, 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 23a 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 main portion 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 consisting of a pole for opening and closing 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 34 and the valve body 35 constitute a 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.

According to the configuration of this embodiment, firstly, the tip of the piston rod 4 is made into a small diameter portion 9 and a cap 11 made of synthetic resin is attached. By inserting the unattached piston rod 4 from the rear space, assembly is facilitated, there is no inconvenience such as the packing 14 being hooked on the piston rod 4 and causing damage, and the cap 11 is in contact with the controlled equipment. This has the advantage of reducing wear.

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 increases, or the pressure in the first chamber 21 increases due to the spring load of the return spring 38. When raised, the packing 14 moves until it comes into contact with the spring receiver 15, and further compresses the push spring 18 and moves to absorb the pressure increase, without impairing the pressure resistance and airtightness of the packing 14.

Thirdly, by fitting the piston stopper 25, the piston 23, and the piston retainer 26 into the piston rod 4 as separate parts, the piston rod 4 can be made smaller in diameter. 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.

Fourth, 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 kept in a fixed position by the partition wall when it is not in operation. The starting point of operation does not change. Furthermore, even if the fluid is liquid, since the amount of sealed liquid is small, there is almost no generation of bubbles at high temperatures, and there is little concern that the characteristics will change. Furthermore, the piston rod is supported by the partition wall and the guide member to ensure stable operation.

Furthermore, when the guide member is made of synthetic resin, consisting of a flange portion and a collar portion, it is possible not only to stably support the piston rod but also to reduce the weight and facilitate the installation of the dust cover.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view showing an embodiment of the present invention, and FIG.
It is an enlarged partial view of the figure. 1... Cylinder tube, 2... Partition wall, 4...
... Piston rod, 5 ... Guide member, 7 ...
...Flange part, 8...Collar part, 14...
...Packing, 21...First room, 22.
...Second chamber, 23... Piston, 32.
...Communication passage, 33... Restriction passage, 37.
...Check valve, 38...Return spring Fig. 1

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. 2. In addition to the configuration described in claim 1, a guide member fixed to the front open end of the cylinder tube is provided, and the piston rod is supported by the partition wall and the guide member so as to be capable of linear reciprocating movement. Features a dashpot. 3. The dashpot according to claim 2, wherein the guide member is made of synthetic resin and has a flange portion fixed to the cylinder tube by caulking and a collar portion extending outward.