JPH0415144B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hydropneumatic brake actuator for controlling a hydraulic brake cylinder installed in a railway vehicle.

(Prior Art) This type of actuator is disclosed in patent application advertisement No. 1983-27146.

This actuator includes a converter 2 including a pneumatic piston 14 and a hydraulic piston 14a, and a hydraulic piston 14a.
The opening end into which the piston was slid and the right chamber 24 of the output piston 4
a hydraulic cylinder having a closed end formed with a passage 35 communicating with the hydraulic cylinder; an adjusting piston 22 incorporated in the hydraulic cylinder so as to be able to slide between the closed end and a stopper formed in the hydraulic cylinder; A first chamber 23 formed between the pressure piston 14a and the adjustment piston 22, a second chamber 37 formed between the adjustment piston 22 and the closed end, and the adjustment piston 2.
2 toward the stopper
, a first check valve 34 that is incorporated into the adjustment piston 22 and blocks the flow of liquid from the first chamber 23 to the second chamber 37; , a liquid storage tank 8 , and a second check valve 26 that blocks the flow of liquid from the first chamber 23 to the liquid storage tank 8 .

When the upper chamber 15 of the pneumatic piston 14 is unpressurized, the first chamber 23, second chamber 37, and chamber 24 are also unpressurized, and the brake is released.

When the chamber 15 is pressurized, the hydraulic piston 14a and the adjustment piston 22 move downward, the liquid in the second chamber 37 flows into the chamber 24, the output piston 4 moves to the left, and the brake shoe 5 moves toward the wheel tread. 6 is pressed to apply the brake.

At this time, the first check valve 34 is opened by the push pin 38, so even if the brake shoe 5 is worn out due to the braking action, the leftward movement of the output piston 4 is not restricted, and the brake is fully applicable.

When the chamber 15 is evacuated, the first chamber 23 becomes unpressurized, the regulating piston 22 is moved upward by the return spring 36, the liquid in the chamber 24 is absorbed into the second chamber 37, and the output piston 4 is It is pulled to the right and the brake is released.

At this time, since the amount of absorption into the second chamber 37 is constant, the amount of rightward movement of the output piston 4 is also constant, and the gap between the brake shoe 5 and the wheel tread is kept constant.

(Problem) As mentioned above, in this actuator, the above clearance is maintained constant even if the brake shoe is worn out, but when a worn brake shoe is replaced with a new one, this clearance becomes smaller than the specified value. There is a problem with getting smaller.

Also, this actuator has a built-in output piston 4, but when this actuator is used in a freight car, there are few devices installed under the floor of the car body, so many brake cylinders are piped to one actuator. It is more economical to connect by

(Technical Means) In order to solve the above-mentioned problems, the actuator according to the present invention has a converting part, a hydraulic cylinder, an adjusting piston, a first chamber, a second chamber, a return spring, a second chamber, etc., as in the prior art. In addition to the first check valve, push pin, liquid storage tank, and second check valve, there is a third check valve that discharges the liquid in the second chamber to the liquid storage tank when the pressure in the second chamber exceeds a certain value. It has been added.

Further, an outlet hole for connecting the second chamber to the hydraulic brake cylinder is additionally provided in the hydraulic cylinder.

(Operation and Effect) When a worn brake shoe is replaced with a new one, the above-mentioned gap becomes smaller than the specified value. Therefore, even if the brake is applied, the adjusting piston does not move to the closed end of the hydraulic cylinder, but temporarily stops on the way. However, when the pressure in the second chamber exceeds a certain value, the third chamber
The check valve opens and the liquid in the second chamber is discharged into the liquid storage tank, so the adjusting piston moves to the closed end.When the brake is then released, the adjusting piston is moved by the return spring and the brake cylinder is closed. Liquid is absorbed into the second chamber. Since the amount of liquid absorbed into the second chamber is constant, the above-mentioned gap becomes a prescribed constant value, and the above-mentioned problems are completely solved.

(Example) The brake actuator shown in the accompanying drawings includes a converter 1, a hydraulic cylinder 2, an adjustment piston 47, a return spring 50, a first check valve 52, a liquid storage tank 44, a second check valve 45, and the main focus of the present invention. The third check valve 53 is a point.

The conversion section 1 includes a large piston 16 and a small piston 12.
and a hydraulic piston 28 coupled to the pneumatic piston, and a control valve 38 is mounted on the upper part of the conversion part 1. The pneumatic pistons 12, 16 and the control valve 38 are identical to those described in patent application no. 59-260973 and are of a construction that allows saving of air consumption associated with braking.

When the control valve 38 is in the relaxed position, the left chamber 13 of the small piston 12 is evacuated, the left chamber 22 and the right chamber 23 of the large piston 16 are both pressurized, and the pneumatic pistons 12, 16 and the hydraulic piston 28 is held in the relaxed position shown by a relaxation spring 32.

A hydraulic piston 28 is slidably fitted to the open end on the left side of the hydraulic cylinder 2, and a closed end 49 is formed on the right side.

The adjusting piston 47 is slidably fitted between a stopper 48 formed inside the hydraulic cylinder 2 and a closed end 49 so as to be able to reciprocate, and is pushed to the left by a return spring 50 and normally rests against the stopper 48. are in contact with each other.

A first check valve 52 is incorporated in the adjustment piston 47, and a first check valve 52 formed on the left side of the adjustment piston 47
The flow of liquid from the chamber 30 to the second chamber 43 formed on the right side is blocked. This first check valve 52 is opened by a push pin 55 driven into the closed end 49 when the adjusting piston 47 moves to the right and comes into contact with the closed end 49 .

The closed end 49 has an outlet hole 56 to which a hydraulic brake cylinder (not shown) installed in the vehicle is connected via piping.

A liquid storage tank 44 is installed above the hydraulic cylinder 2, and a second check valve 45 is installed to prevent liquid from flowing from the first chamber 30 to the liquid storage tank 44.

Further, a third check valve 53, which is the main point of the present invention, is installed between the second chamber 43 and the storage tank 44, and
When the pressure in the second chamber 43 exceeds a certain value,
of liquid is discharged into the storage tank 44.

When the hydraulic piston 28 is in the illustrated relaxed position, the hydraulic brake cylinder connected to the first chamber 30, the second chamber 43, and the outlet hole 56 is unpressurized;
The brakes are released.

When the control valve 38 assumes the brake position, the left chamber 13 of the small piston 12 is first pressurized, the hydraulic piston 28 moves to the right, and along with this movement to the right, the adjustment piston 4
7 moves to the right until it comes into contact with the closed end 49, the first check valve 52 is opened by the push pin 55, and the first chamber 3
0 liquid is released from the first check valve 52 and the outlet hole 5.
6 to a hydraulic brake cylinder (not shown), and the brake shoe (not shown) lightly contacts the wheel tread (not shown). Also large piston 1
6 slides into the cylinder 21, and communication between the chambers 22 and 23 is cut off.

After that, when the pressure in the chamber 13 reaches a certain value, the control valve 38 is operated to reduce the pressure in the chamber 23, and the output of the hydraulic piston 28 increases due to the pressure difference between the chambers 22 and 23, and the pressure in the first chamber 30 increases. The pressure increases and this pressure is transmitted to the hydraulic brake cylinder to apply brakes to the vehicle.

Even if the brake shoe is worn out during braking and the stroke of a piston (not shown) included in the brake cylinder increases, liquid will flow from the first chamber 30 through the first check valve 52 that is open. Since the brake fluid is replenished, there is no risk that the braking force will decrease.

When the control valve 38 assumes the relaxed position, the chamber 23 is pressurized to the same pressure as the chamber 22, the chamber 13 is evacuated, the output of the hydraulic piston 28 becomes 0, and the first chamber 30
becomes pressureless. Therefore, the adjusting piston 47 is pushed by the return spring 50 and moves to the left until it comes into contact with the stopper 48, and the fluid in the brake cylinder is absorbed into the second chamber 43. At this time, since the amount of liquid absorbed into the second chamber 43 is constant, the amount of retraction of the piston of the brake cylinder is also constant, and the gap between the brake shoe and the wheel tread is maintained at a specified value.

Further, when the hydraulic piston 28 moves further to the left after the adjustment piston 47 contacts the stopper 48, the pressure in the first chamber 30 becomes less than atmospheric pressure, and the pressure in the first chamber 30 is transferred from the storage tank 44 through the second check valve 45 to the first chamber. The liquid is replenished at 30.

When replacing worn brake shoes with new ones, the gap mentioned above will be smaller than the specified value.
In this case, even if the brake is applied, the adjustment piston 47
stops once before contacting the closed end 49. However, when the pressure in the second chamber 43 reaches a certain value, the liquid is discharged into the storage tank 44 via the third check valve 53, so the adjusting piston 47 moves until it abuts the closed end 49. Therefore, when the brake is subsequently released, a certain amount of liquid is absorbed from the brake cylinder into the second chamber 43 due to the leftward movement of the adjusting piston 47, and the above-mentioned gap is maintained at a specified value. When the brake shoe is replaced in this way, the above-mentioned gap is corrected to the specified value all at once by one brake operation.

[Brief explanation of drawings]

The attached figure is a sectional view of a brake actuator showing an embodiment of the present invention. 1... Conversion section, 2... Hydraulic cylinder, 12...
Pneumatic piston, 16... Pneumatic piston, 28
... Hydraulic piston, 30 ... First chamber, 43 ... Second chamber, 44 ... Liquid storage tank, 45 ... Second check valve,
48...Stopper, 49...Closed end, 50...
Return spring, 52...first check valve, 53...third check valve, 55...push pin, 56...exit hole.

Claims (1)

[Claims] 1. A hydropneumatic brake actuator used in a railway vehicle having a hydraulic brake cylinder and consisting of the following parts: (a) Pneumatic pistons 12, 16 and a hydraulic piston 2
(b) a hydraulic cylinder 2 having an open end to which the hydraulic piston is slidably fitted and a closed end 49; (c) the hydraulic cylinder; Stopper 4 formed in
an adjusting piston 4 incorporated in said hydraulic cylinder so as to be able to slide between said closed end and said closed end;
7. (d) a first chamber 30 formed between the adjustment piston and the hydraulic piston; (e) a second chamber 43 formed between the adjustment piston and the closed end; (f) (g) a return spring 50 that presses the adjustment piston in the direction of the stopper;
a check valve 52; (h) a push pin 55 that opens the first check valve when the adjusting piston abuts the closed end; (i) a liquid storage tank 44; (j) a connection from the first chamber to the storage tank. (k) a third check valve 53 that discharges the liquid in the second chamber to the storage tank when the pressure in the second chamber reaches a certain value; , and (l) an outlet hole 56 located at the closed end of the hydraulic cylinder and connecting the second chamber to the hydraulic brake cylinder.