JPS6220731Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a brake valve used as a brake device for industrial machinery, etc.

(Prior Art) The second conventional brake valve has a counterbalance valve 40 connected to the upstream side of the hydraulic motor m, and a main passage 41 and 42 connecting the hydraulic motor m and the counterbalance valve 40. A pair of crossover type relief valves l ₁ and l ₂ are provided.

The crossover type relief valves l ₁ and l ₂ have their inflow sides 43 and 44 communicating with the main passages 41 and 42, and their outflow sides 45 and 46 with the main passages 42 and 41 on the opposite side. There is.

Shockless cylinders 49, 50 are connected to the secondary pressure chambers 47, 48 of the relief valves l ₁ , l ₂ , and these cylinders 49, 50 have free pistons 59, 60 inside, and the pressure chambers 51, 52 and spring chambers 53, 54. The pressure chambers 51 and 52 are communicated with the secondary pressure chambers 47 and 48, and the spring chamber 53 is communicated with the main passage 42 on the opposite side.
is communicated with the main passage 41 on the opposite side.

A switching valve (not shown) is connected to the upstream side of the counterbalance valve 40, and when this switching valve is switched, one of the passages 55 and 56 communicates with the pump, and the other passage communicates with the tank. do. When pressure oil is supplied to either passage, the pressure oil acts on the pilot chamber 57 or 58 of the counterbalance valve 40, switching the counterbalance valve 40 to either the left or right position.

Note that the relief valves l ₁ and l ₂ have orifices formed in their poppets, and communicate the inlet sides 43 and 44 with the secondary pressure chambers 47 and 48 via the orifices, as well as the inlet sides 43 and 48 of the poppets. ,4
The pressure receiving area of the secondary pressure chambers 47 and 48 is made smaller than that of the secondary pressure chambers 47 and 48.

When the switching valve is switched, for example, the passage 55 is made to communicate with the pump and the passage 56 is made to communicate with the tank, the pressure oil on the passage 55 side acts on the pilot chamber 57 of the counterbalance valve 40, and the counterbalance valve 40 is activated. Switch the valve 40 to the left position in the drawing.

When the counterbalance valve 40 is switched to the left position, the pressure oil in the passage 55 pushes open the check valve 61 and flows into the hydraulic motor m via one of the main passages 41. At this time, the return oil from the hydraulic motor m is returned to the tank from the other main passage 42 via the passage 56.

The hydraulic motor is started as described above, but at this time, the pressure oil in one of the main passages 41 flows into the secondary pressure chamber 47 via the orifice formed in the poppet of the relief valve _l1 . It flows into the pressure chamber 51 of the shockless cylinder 49 from the next pressure chamber. When pressure oil flows into the pressure chamber 51 in this way, the free piston 59 moves into the spring chamber 53.
The pressure chamber 51 moves against the spring of the pressure chamber 51 and expands the volume of the pressure chamber 51. While the volume of the pressure chamber 51 is expanding, a flow is generated in the orifice formed in the relief valve _l1 , so that the poppet is opened by the pressure difference before and after the orifice.

Then, when the free piston 59 makes a full stroke, the flow in the orifice disappears, so
This time, the relief valve will open according to the difference in the pressure receiving area of the poppet.

That is, while the free piston 59 is moving to increase the volume of the pressure chamber 51, the relief valve _l1 is set to a low pressure, and the free piston 59
After the full stroke, the pressure is set to high.

The pressure on the main passage 41 side also acts on the spring chamber 54 of the shockless cylinder 50 connected to the relief valve _l2 . This pressure action and the spring force of the spring in the spring chamber 54 move the free piston 60 to the pressure chamber 52 side, and the hydraulic oil in the pressure chamber 52 is forced to the relief valve _l2.
The secondary pressure chamber 48 and the orifice formed in the poppet are connected to the low pressure main passage 42.
Push it out to the side.

Therefore, as long as the motor m is being driven, the shotless cylinder 49 connected to the secondary pressure chamber 47 of the relief valve _l1 is maintained at the full stroke position that maximizes the volume of the pressure chamber 49. It will be done. Further, the shockless cylinder 50 connected to the secondary pressure chamber 48 of the relief valve _l2 is set at an initial position that minimizes the volume of the pressure chamber.

In the above state, when the switching valve is returned to the neutral position and both passages 55 and 56 are communicated with the tank, the pilot chamber 57 of the counterbalance valve 40 also becomes tank pressure, so the counterbalance valve 40 is moved to the neutral position shown in the figure. It returns to the position and closes the main passages 41 and 42.

Even when the main passages 41 and 42 are closed, the motor m continues to rotate due to its inertia, so the motor m performs a pumping action to discharge the hydraulic oil sucked in from the main passage 41 side into the main passage 42. . Therefore, the main passage 42, which has been at low pressure until now, becomes high pressure, and the high pressure oil flows into the main passage 41 on the opposite side via the relief valve _l2 .

Therefore, main passage 41→hydraulic motor m→
A short circuit is formed by the main passage 42→relief valve _l2 , and when the pressure oil on this main passage 42 side passes through the relief valve _l2 ,
The inertial energy of the hydraulic motor m is absorbed.

Then, at the moment when the counterbalance valve 40 is switched to the neutral position, the pressure on the main passage 42 side suddenly becomes high and a shock occurs in the hydraulic motor m. At this time, the shockless cylinder 50 operates to prevent the above-mentioned shock. Absorb.

That is, since the free piston 60 of the shockless cylinder 50 is set at the initial position as described above, when the pressure in the main passage 42 increases, the pressure oil is transferred to the secondary pressure chamber ₄ of the relief valve l2.
8 into the pressure chamber 52 and moves its free piston 60 against the spring force of the spring of the spring chamber 54, thereby increasing the volume of the pressure chamber 52.

If the volume of the pressure chamber 52 increases as described above,
As described above, the set pressure of the relief valve _l2 becomes low. Therefore, the above-mentioned shock will be absorbed.

(Problems to be solved by the present invention) When exerting braking force with the crossover type relief valve as described above, the hydraulic oil is heated to convert the inertial energy into thermal energy. The volume expands. When the volume of hydraulic oil expands in the shot circuit, the pressure in that circuit increases.In particular, this pressure increase acts as back pressure on the crossover type relief valve, so that the relief valve in question exceeds the set pressure. The problem is that it will not work unless the pressure is high.

Furthermore, when the set pressure of the relief valve becomes high as described above, the pressure on the discharge side of the motor increases abnormally, which causes damage to piping, other valves, etc.

Furthermore, the oil temperature rose, which could damage seals and cause the motor to seize.

The purpose of this invention is to drain high-pressure oil in a shot circuit by using a shotless cylinder of a crossover type relief valve, thereby preventing high pressure in the shot circuit.

(Means for solving the problem) In order to achieve the above object, this invention is configured as follows.

That is, the motor is connected to the downstream side of a pair of main passages formed in the casing, and a pair of crossover type relief valves are provided, and the inflow sides of the relief valves are communicated with the respective main passages.
The outflow side is communicated with the main passage on the opposite side to the inflow side, and an orifice is formed in this relief valve, and the pressure oil on the inflow side is introduced into the secondary pressure chamber through this orifice. While the relief valve is operated by the difference in pressure receiving area before and after the orifice, a free piston is installed in the shotless cylinder, a spring is applied to the free piston, and a pressure chamber is formed on the opposite side of the spring. The secondary pressure chamber of the relief valve is communicated with the pressure chamber, and the spring side of the free piston is communicated with a main passage different from the main passage connected to the inflow side of the relief valve with which the pressure chamber communicates. , in a brake valve in which a counterbalance valve is connected to the upstream side of the crossover type relief valve, a port is formed to communicate the spring side acting on the free piston with the outer periphery of the free piston. At the same time, a drain hole is formed in the shortless cylinder to communicate with the port during the movement process of the free piston.

(Operation of the present invention) When the motor performs a pumping action and a shot circuit is formed, the high pressure acts on the pressure chamber of the shotless cylinder and moves its free piston against the spring. When the free piston moves in this manner, the port formed in the free piston coincides with the drain hole during the movement process. Since this drain hole communicates with the outflow side of the crossover type relief valve, the hydraulic oil that has passed through this relief valve is drained from the drain hole.

(Effects of the present invention) According to the brake valve of this invention, the hydraulic oil that has passed through the crossover type relief valve is drained through the drain hole during braking to form the short circuit, so that the heat of the hydraulic oil is All harmful effects caused by expansion can be eliminated.

In addition, by simply forming a port on the free piston and a drain hole on the shoulderless cylinder,
Since the hydraulic oil can be drained, the conventional brake valve can be used as is.

Moreover, since the port and the drain hole are communicated with each other during the movement of the free piston as described above, the communication time can be arbitrarily adjusted by changing the size of the drain hole.

(Embodiment of the present invention) The casing 1 includes a counterbalance valve 2, crossover type relief valves 3 and 4, and the casing 1.
Although the shock absorber is provided with shockless cylinders 5 and 6, each of these components is the same as the conventional one.

The counterbalance valve 2 forms pump ports 7, 8 and motor ports 9, 10, and also connects both ends of the spool 11 to a pilot chamber 12,
I am facing the 13th. And this spool 11
are equipped with check valves 14 and 15 that allow flow only from the pump port to the motor port.

If a switching valve (not shown) is operated to introduce pilot pressure into the pilot chamber 12, the spool 11 will move to the left side in the drawing, causing the pump port 8 to communicate with the motor port 10, and also connecting the pump port 8 to the tank. In addition, the other pump port 7 is connected to the pump.

Therefore, the pressure oil from the pump pushes open the check valve 14 and flows into the motor m from the motor port 9 via the main passage 34. On the other hand, return oil from the motor m returns to the tank from the main passage 33 via the motor port 10 and the pump port 8.

Further, since the crossover type relief valves 3 and 4 and the shockless cylinders 5 and 6 have the same structure, only one of the relief valves 3 and the shockless cylinder 5 will be described.

In the relief valve 3, a sleeve 26 having a seat member 25 fitted at its tip is inserted into the casing 1, and a poppet 16 is installed inside the sleeve 26. This poppet 16 is connected to a spring 28 installed in the secondary pressure chamber 18 inside the sleeve 26.
As a result, the short circuit passage 29 normally comes into pressure contact with the valve seat of the seat member 25 and blocks communication between the short circuit passage 29 communicating with one motor port 9 and the short circuit passage 30 communicating with the other motor port 10. An orifice 17 is formed in the poppet 16 of this relief valve 3, and the short circuit passage 3 is connected to the short circuit passage 3 through this orifice 17.
0 and the secondary pressure chamber 18 are communicated with each other. and,
The pressure receiving area S2 on the secondary pressure chamber ₁₈ side is made smaller than the pressure receiving area _S1 of the poppet 16 facing the seat member 25 side.

Note that the short-circuit passage 30 side is defined as the inflow side of this invention, and the short-circuit passage 29 side is defined as the outflow side.

Further, the above-mentioned shockless cylinder 5 is integrated with the casing 1, and a free piston 20 is installed inside the cylinder 5. A spring chamber 35 is formed on one side of the free piston 20, a spring 21 is interposed in the spring chamber 35, and the spring force of the spring 21 is applied to the free piston 20. The spring chamber 35 is communicated with the main passage 33 via the short-circuit passage 29, and a pressure chamber 31 is formed on the opposite side of the spring chamber 35. It communicates with the secondary pressure chamber 18 via.

The free piston 20 configured as described above is formed with a port 22 that communicates the spring chamber 35 with the outer circumference of the free piston 20, and in the process of the piston 20 moving against the spring 21,
The port 22 communicates with the drain hole 23, and the spring chamber 35 and branch passage 29 side is connected to the drain hole 23.
It communicates with the tank 24 via.

When pilot pressure is introduced into the pilot chamber 12 and the spool 11 is moved to the left in the drawing,
One motor port 9 side is connected to the pump via the pump port 7, and the other motor port 10 side is connected to the tank via the pump port 8 to drive the motor m. When the control valve is switched to the neutral position from this state, the pressure in the pilot chamber 12 becomes the tank pressure, so the spool 11 of the counterbalance valve 2 returns to the neutral position shown. Even when the spool 11 returns to the illustrated neutral position, the motor m continues to rotate due to its inertia.
acts as a pump. For this purpose, the pressure oil discharged from this motor m acts on the poppet 16 of the relief valve 3 via the branch passage 30, and
This pressure oil also flows into the secondary pressure chamber 18 via the orifice 17.

When pressure oil flows into the secondary pressure chamber 18, this pressure oil flows into the pressure chamber 31 via the communication hole 32 and the passage 19, and the free piston 20 is moved to the left in the drawing by its pressure action. When the free piston 20 moves as described above, the volume of the pressure chamber 31 expands as the free piston 20 moves. And the pressure chamber 31
While the volume of the secondary pressure chamber 18 is expanding, the hydraulic oil in the secondary pressure chamber 18 flows into the pressure chamber 31, so a pressure difference is generated before and after the orifice 17 formed in the poppet 16. The effect of this differential pressure and the difference between the pressure receiving areas S ₁ and S ₂ act synergistically, and the relief valve 3 is set to a low pressure. While the free piston 20 is operating in this way, in other words, at the start of the braking operation, the set pressure of the relief valve 3 is set low to alleviate the shock when a sudden braking force is applied. This is to do so.

When the free piston 20 reaches its stroke end, the flow of hydraulic oil in the secondary pressure chamber 18 stops, so the pressures before and after the orifice 17 become equal. At this time, the relief valve 3 opens according to the difference between the pressure receiving areas S ₁ and S ₂ and the spring force of the spring 28, so the relief valve 3 is set to a high pressure.

When the motor m performs the pumping action as described above, the high pressure oil flows from the branch passage 30 to the relief valve 3 to
A short circuit is formed through the branch passage 29 and the motor m, and when the high-pressure oil passes through the relief valve 3, the inertial energy of the motor m is converted into thermal energy and braking force is exerted.

Note that the above operation is exactly the same as in the conventional case shown in FIG.

Further, when the free piston 20 moves at the start of brake operation, the port 22 communicates with the drain hole 23 during the movement process, so the hydraulic oil that has leaked into the branch passage 29 flows through the drain hole 23 to the tank 23. leaks into Therefore, a portion of the hydraulic fluid in this short circuit is discharged into tank 24.

Note that the timing or length of matching the port 22 and the drain hole 23 is not necessarily limited. However, port 22 and drain hole 2
3, it is not allowed to remain in communication because the amount of hydraulic oil in the circuit will decrease.

The greatest feature of this invention is that the movement of the free piston is utilized to discharge the hydraulic oil in the short circuit for a limited period of time.

Note that even in the process of the free piston returning from the full stroke position to the original position, the port 22 and the drain hole 23 communicate with each other to drain a portion of the pressure oil. Even if a portion of the supplied oil is drained in this way, pressure oil is continuously supplied from the pump, so there is no problem in driving the motor m.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing an embodiment of this invention;
FIG. 2 is a circuit diagram of a conventional brake valve. 1...Casing, 3, 4...Crossover type relief valve, 5, 6...Shockless cylinder,
17... Orifice, 18... Secondary pressure chamber, 20...
...Free piston, 22...Port, 23...Drain hole, 31...Pressure chamber, 33, 34...Main passage.

Claims (1)

[Scope of utility model registration request] A motor is connected to the downstream side of a pair of main passages formed in the casing, and a pair of crossover type relief valves are provided, the inflow sides of the relief valves are connected to each main passage, and the outflow sides are connected to the inflow side. The relief valve is connected to the main passage on the opposite side, and an orifice is formed in this relief valve, and the pressure oil on the inflow side is introduced into the secondary pressure chamber through this orifice. While operating based on the pressure receiving area difference, a free piston is installed in the shotless cylinder, a spring is applied to this free piston, and a pressure chamber is formed on the opposite side of the spring, and the secondary pressure chamber of the relief valve is communicates with the pressure chamber, and communicates the spring side of the free piston with a main passage separate from the main passage connected to the inflow side of the relief valve with which the pressure chamber communicates, and In a brake valve having a counterbalance valve connected to the upstream side, a port is formed in the free piston and allows the spring side acting on the free piston to communicate with the outer periphery of the free piston, and a port is formed in the shockless cylinder, A brake valve in which a drain hole communicating with the port is formed during the movement process of the free piston.