RU2447329C2 - Pneumatic drive with braking device - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: pneumatic drive with a braking device comprises a cylinder, a braking chamber, a piston with a single-sided stem, a controlled throttle, and also a ledge, an inlet hole connecting a piston cavity with a source of gas, and an outlet hole connecting the stem cavity with atmosphere. The ledge is made as covering the stem and is installed on the cover at the side of the stem, besides, the inner diameter of the ledge is equal to the stem diameter, at the same time the ledge end is arranged at the distance equal to the stem travel χ_st., in the stem on its axis there is a dead hole, the outlet of which at the side of the end opposite to the piston is connected to atmosphere, and at the distance ℓ from the piston end facing the stem there is an inlet through hole, which is perpendicular to the axis of the dead hole, at the same time a pneumatic distributor installed at the inlet to the piston cavity is made in the form of an injection nozzle connected directly to a throttle of permanent cross section, and at the outlet of the stem cavity there is a controlled throttle installed on the outlet hole.

EFFECT: invention makes it possible to control speed of pneumatic cylinder piston movement along with the stem travel.

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Description

The invention relates to the field of mechanical engineering and can be used in those areas, in particular in space technology, for opening the landing device of a manned transport spacecraft, where it is necessary to brake the piston of the pneumatic cylinder at the end of its movement to avoid an impact that is undesirable or unacceptable.

Known pneumatic actuator with a hydraulic brake, containing two cylinders, one of which is pneumatic power, the other hydraulic brake, the pistons of which are placed on a common rod [T. M. Bashta. Hydraulic drive and hydropneumatic automation. M.: Engineering, 1972, p. 303].

Braking of the piston of the pneumatic cylinder is carried out by a throttle hole made in the piston of the brake hydraulic cylinder. The disadvantage is the inability to control the speed in the path of the piston, since the hydraulic resistance of the throttle hole is constant, and the hole itself is located inside the hydraulic cylinder, which makes it difficult to carry out the adjustment.

Also known is a pneumatic actuator with an internal brake device - the closest analogue (prototype) described in [T.M. Bashta. Hydraulic drive and hydropneumatic automation. M.: Mechanical Engineering, 1972, p. 293].

Pneumatic actuator - the prototype contains a cylinder, braking chambers on both sides of the cylinder, a piston with a one-sided rod and two protrusions, the diameter of which is equal to the diameter of the braking chamber, two holes in each cavity, which serve as air supply and exhaust, an adjustable throttle and a non-return valve, which serves to supply air into the cavity bypassing the throttle.

The operation of the pneumatic actuator is as follows. The power of the cylinder and the movement of its piston occurs in the usual way until the corresponding protrusion on the piston overlaps one of the chambers. After the cylinder piston overlaps the chamber with its protrusion when moving, for example, to the left, and the diameters of the chamber and protrusion are equal, air can be removed from the exhaust cavity only through an adjustable throttle of small cross section, as a result, air in this cavity is compressed, slowing down the movement with an intensity determined by throttle adjustment. The piston returns to its original position after switching the control air distributor (not shown in the diagram) under the influence of air flowing into the right cavity bypassing the throttle through a check valve. At the end of the piston stroke, the brake device of the left cylinder cavity comes into action.

The disadvantage of such a brake device is the difficulty of adjusting the start of its inclusion along the piston.

The task of a pneumatic actuator with a brake device is to ensure the movement of the rod from the stop of the initial position to the stop of the final position, while in the second section of the path the speed of movement of the piston should be minimal to reduce the energy of impact of the piston against the stop of the final position.

The technical result of the present invention is the ability to control the speed along the piston of the pneumatic actuator.

The technical result is achieved due to the fact that in a pneumatic actuator with a brake device containing a cylinder, a braking chamber, a piston with a one-sided rod, an adjustable throttle, as well as a protrusion, an inlet that connects the piston cavity to the gas source, and an outlet that connects the rod cavity with the atmosphere, in it, unlike the known one, the protrusion is made covering the rod and placed on the cover from the side of the rod, while the inner diameter of the protrusion is equal to the diameter of the rod, and the end face of the protrusion is located at a distance Equal move stem x _units in stock on its axis a blind hole, the yield of which from the end opposite the piston, connected with the atmosphere, and at a distance l from the end of the piston facing the rod, holds inlet through hole perpendicular to the axis of the blind bore at the same time, the pneumatic distributor installed at the inlet to the piston cavity is made in the form of a discharge nozzle connected directly with a constant-flow inductor, and an adjustable throttle is installed at the outlet of the rod cavity at the outlet spruce.

Thus, thanks to this technical solution, it is possible to control the speed of the piston of the pneumatic cylinder along the rod and provide braking in the second leg.

In the inventive pneumatic actuator, the function of the brake device is performed by the inner cylindrical surface of the protrusion when interacting with the surface of the rod at the location of the through hole perpendicular to the blind hole made in the axis of the rod. When the piston is moved to a distance l> x _pc relative to the original plane, the through hole is closed and the piston is decelerated. In contrast, in the prototype pneumatic actuator, the function of the braking device when interacting with the protrusion on the piston is performed by the surface of the braking chamber located at the end of the cylinder, while the outer diameter of the protrusion is equal to the diameter of the braking chamber.

The implementation of the claimed technical solution is illustrated using the pneumatic actuator drawing. In the drawing, the numbers indicate:

1 - housing;

2 - cylinder;

3 - the piston;

4 - stock;

5 - a cover with an emphasis;

6 - cover with a protrusion;

7 - blind hole;

8 - through hole;

9 - input fitting;

10 - input choke;

11 - output choke;

12 - outlet.

An inlet fitting 9 and an inlet throttle 10 are mounted on the housing 1 for connecting the piston cavity of the power cylinder 2 with an air pressure source (Inlet). The master cylinder 2, located inside the housing 1, is closed by a cover 5 with an emphasis facing the piston (on the drawing on the left), and on the right is closed by a cover 6, on which a protrusion is made, covering the rod, while the end face of the protrusion is placed at a distance equal to the stroke x _pcs relative to the right end face of the piston (reference plane A). Inside the cylinder 2, a piston 3 with a rod 4 is installed, in the center of which a blind hole 7 is made from the end face of the rod, while at the end of this hole, a through hole 8 is drilled perpendicular to the axis of the blind hole at a distance l from plane A to communicate with the right cylinder cavity which through the adjustable throttle 11 and the outlet 12 communicates with the atmosphere (Exit). The rod 4 with blind and through holes, the inner surface of the protrusion of the cover 6 and the adjustable throttle 11 with the outlet 12 form a braking device.

Consider the operation of a pneumatic actuator with a brake device.

When compressed air enters through the inlet nipple 9 and the throttle 10 into the piston cavity of the cylinder 2, the piston 3 with the rod 4 begins to move to the right under the influence of a pressure differential, while the air displaced by the piston through the through hole 8 and the blind hole 7 is released into the atmosphere. The distance between the hole 8 and the original plane And increases from l to x _pcs . When passing a distance, for example, 2/3 _pcs or more, the hole 8 is blocked by the inner cylindrical surface of the protrusion of the cover 6, and the rest of the way in 1/3 x _{pcs, the} displaced air is forced to escape into the atmosphere through an adjustable orifice 11 of small cross section and an outlet 12, as a result, the speed of the rod decreases and the rod is braked in the region of the stop of the final position, the role of which is the protrusion of the cover. By selecting the cross section of the throttle 10, you can adjust the maximum speed of the piston in the first section of the path, and by adjusting the throttle 11 you can change the speed of the piston in the second section of the path. By choosing the ratio between the dimensions l and x _pcs, you can set the time at which braking starts.

Thus, the inventive pneumatic actuator provides speed control of the piston of the pneumatic cylinder along the rod.

Claims (1)

A pneumatic actuator with a brake device, comprising a cylinder, a braking chamber, a piston with a one-way rod, an adjustable throttle, and also a protrusion, an inlet connecting the piston cavity to a gas source, and an outlet opening connecting the rod cavity to the atmosphere, characterized in that it has a protrusion made covering the rod and placed on the lid on the side of the rod, while the inner diameter of the protrusion is equal to the diameter of the rod, and the end face of the protrusion is placed at a distance equal to the stroke of the rod x _pcs , in the rod on its axis is blind the second hole, the outlet of which from the end face opposite the piston is connected to the atmosphere, and at a distance l from the end face of the piston facing the rod, an inlet through hole is made perpendicular to the axis of the blind hole, while the pneumatic distributor installed at the inlet to the piston cavity is made in the form of a discharge fitting connected directly to a constant-flow inductor, and at the outlet of the rod cavity, an adjustable orifice is installed at the outlet.

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