JPS6252272A - Hydraulic closed circuit for driving inertia substance - Google Patents

Abstract

PURPOSE:To simplify stop operation by introducing pressure in main passes on both sides of a pump through a shuttle valve to one end of a cutoff valve's spool, and installing a spring to the other end. CONSTITUTION:Pressure in main passes 2, 3 on both sides of a variable volume type pump 4 is introduced through a shuttle valve 21 to one end of a cutoff valve (11)'s spool 20 in a hydraulic closed circuit for driving inertial substance and a spring 23 is installed on the other end. And pilot pressure for braking and pilot pressure for servo valve control both from a remote control valve 24, are introduced through a shuttle valve 36. Therefore, it is easy to stop operation as an inertial substance in a neutral flow situation surely stops by putting an operation lever staying at a neutral position into a braking position.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is mainly concerned with an inertia system that enables long rotating bodies found in hydraulic excavators, various cranes, etc. to freely rotate when the operating command pressure is zero. The present invention relates to a body drive hydraulic closed circuit.

[Conventional technology]

This type of hydraulic circuit includes one in which the control lever is operated to drive the inertia body, and then the brake is applied in the process of returning the control lever to the neutral position, and the other is to operate the control bar in the opposite direction after passing through the neutral position. If you don't do this, the brakes may not work.

An example of the hydraulic closed circuit of the latter reverse lever operation method is shown in Figure 2 (
(Japanese Patent Application Laid-Open No. 5El-46257), when the operating lever 52 of the remote control valve 51 is operated from the neutral position in the direction of the arrow, the variable pressure reducing valve 53 is operated and the pump 54 is operated.
The pilot pressure Pi from the liquid chamber 34 of the servo valve 10 and
It is guided to one end of the cut-off valve 11 through the shuttle valve 55, and the spool 13 moves to the right and the cut-off valve 11 assumes its position. Therefore, the servo pressure from the servo pump 12 is introduced into the liquid chamber 9 of the servo cylinder 6, and the liquid chamber 8 is communicated with the link 38, and the servo piston 7 moves to the left to increase the pump tilt angle. Pressure oil is discharged from the main flow path 3. However, the hydraulic motor 1 is not accelerated immediately due to the inertia body attached to it, and a hydraulic pressure Pd is generated in the main flow path 3. This oil pressure opposes the spring 23 and the pilot pressure Pi via the spool 20 of the cut-off valve 11, but since the pressing force on the spring side is strong, the position of the cut-off valve 1 remains unchanged and servo pressure is applied to the liquid chamber 9. Since it is guided, hydraulic motor 1
is being accelerated. Then, when the operating lever is turned once, the pilot pressure becomes constant and when the sleeve 18 moves to the spool position corresponding to this pilot pressure, the passage hole of the sleeve 18 is closed by the spool 13 and the servo piston 7 is closed.
As a result of being hydraulically locked, the hydraulic motor 1 rotates at a constant speed.

When the operating lever 52 is returned to the neutral position, the pilot pressure p i fJ<0 and the cut-off valve 11 is released by the spring 23.
The spool 13 of the spring valve 10 returns to the neutral position by the springs 14 and 15, but the sleeve 18
does not return, the servo piston 7 begins to return to the neutral side due to the servo pressure introduced into the liquid chamber 8, and the pump discharge M decreases. On the other hand, since the hydraulic motor 1 attempts to continue rotating by pumping with the inertia force of the inertial body, a blow pressure Pd' is generated in the main flow path 2, but the force of the spring 23 is weak compared to the hydraulic pressure. (When a low brake pressure Pd' occurs, the cut-off valve 11 switches to position a, and the liquid chambers 8 and 9
The servo piston 7 is released from hydraulic pressure to communicate with the tank 38. Therefore, the inertial body continues to rotate freely due to its inertial force, resulting in a so-called neutral flow state.

In this state, when the operating lever 52 is operated from the neutral position in the direction opposite to the arrow, the variable pressure reducing valve 56 is activated and the pilot pressure Pi from the pump 54 is applied to the liquid chamber 33 of the servo valve 10.
is guided to one end of the cut-off valve 11 via the shuttle valve 55, and the sub-motor 3 moves to the left and the cut-off valve 11 takes its position, so servo pressure is generated in the liquid chamber 8 and the servo piston 7 moves to the right. do. As a result, the pump discharge amount to the main flow path 3 decreases, and brake pressure is generated in the main flow path 2, and the inertial body is accelerated by this brake pressure and comes to a stop [Problem to be solved by the invention] [Point] In the above-mentioned reverse lever operating method, unless the operating lever is returned to the neutral position at the timing when the hydraulic motor stops +1-, the hydraulic motor will rotate in the opposite direction again. Further, when the hydraulic motor body is stopped (when the operating lever is in the neutral position, the pressure is zero), the hydraulic motor may be rotated by an external force. That is, when the hydraulic motor at rest is subjected to an external force, a counter-motor holding pressure acts on the pump 4, and the servo piston 7 is moved.

For example, when the servo piston is moved to the right, the sleeve 18 that is interlocked with this moves to the left, and the spool 13
Since is in the neutral position, the servo pressure Ps is guided to the liquid chamber 9,
Trying to stop the movement of the servo piston 7. However, the motor holding pressure simultaneously acts on the cutoff valve 11 and switches the cutoff valve to position a, so both liquid chambers 8 and 9 of the servo piston 7 are communicated with the tank 38, and the servo piston 7 is released from the hydraulic pressure. Therefore, the hydraulic motor is rotated by external force.

The present invention aims to eliminate the above-mentioned drawbacks.

[Means for solving problems]

The structure of the present invention for achieving the above object will be explained using FIG. 1 corresponding to an embodiment. A hydraulic motor 1 connected to an inertial body (not shown), and a main flow path 2 to the hydraulic motor 1.
3, a variable displacement pump 4 connected to form a closed circuit, and a servo piston 7 that controls the pump tilt angle.
and an inertial body drive hydraulic pressure including a spool 13 controlled by pilot pressure and a servo valve 10 that has a sleeve 18 that interlocks with the servo piston 7 and controls the servo piston 7 by the servo pressure guided through the cutoff valve 11. In the closed circuit, the spool 20 of the cut-off valve 11 has one end to guide the pressure of the main channels 2 and 3 on both sides of the variable displacement pump 4 via a shuttle valve 21, and a spring 23 to the other end. The brake pilot pressure from the control valve 24 and the nodal pressure of the servo valve control pipe 11 are guided through the shuttle valve 36.

[For production]

In the illustrated state where the pump 4 and the oil I'f-motor 1 are at rest, the inertial body is The inertial body rotates freely due to its inertial force by turning the operating lever 35 to the (center) γ position after turning the operating lever 11° to drive the hydraulic motor 1 steadily. This is similar to the conventional device in which there is only one word in the flow state.

In the present invention, in order to stop the inertial body in the neutral position, the operating lever 25 is moved from the neutral position to the brake position. As a result, the variable pressure reducing valve 28 is actuated, and the pressure from the pump 30 acts on the spring-side spool end of the cut-off valve 11 via the shuttle valve 36, causing the cut-off valve to
Switch the off valve 11 to the position. In this case, servo valve 10
The spool 13 is in the neutral position (☆ position, but the sleeve 18 is in the center f position and in order to guide the servo pressure to the liquid chamber 9, the servo piston 7 and sleeve 18 move to the neutral side and reduce the pump tilt angle. When the servo piston 7 reaches the neutral position, the servo piston 7 is hydraulically locked by the servo valve 10, so that the hydraulic motor 1 stops operating.

If the operating lever 25 is left in the brake position, the pilot pressure is guided to the cut-off valve 11, so an external force is applied to the hydraulic motor 1, and a counter-motor holding pressure acts on the cut-off valve 11. Also cut-off valve 1
1 takes position yb and guides the servo pressure to the servo valve 10. On the other hand, the motor holding pressure acts on the pump 4 and the servo piston 7
When the sleeve 8 is moved, the interlocking sleeve 8 also moves, but since the spool 13 is in the neutral position, the servo pressure pushes the servo valve IO back to the neutral position. Therefore, when the hydraulic motor is at rest, it is not rotated by external force.

〔Example〕

Embodiments of the present invention will be described based on the drawings. In FIG. 1, a hydraulic motor 1 connected to a rotating body (inertial body) not shown and a variable displacement pump 4 are connected by main channels 2 and 3 to form a closed circuit.

The tilting portion of the variable displacement pump 4 is connected to a servo piston 7 of a servo cylinder 6 via a tilting lever 5, and the liquid chambers 8 and 9 facing the servo piston 7 are connected via a servo valve 10 and a cut-off valve 11. It is connected to the ζ servo pump 12.

The servo valve 10 has a neutral return spring 14.15 disposed at both ends of the spool 13 via a pilot piston 16.17, and a sleeve 18 is connected to the servo piston 7 via a feed mechanism 19 to connect the servo piston. 7 and are linked in opposite directions.

The cut-off valve 11 guides the pressure of the main channels 2 and 3 on both sides of the pump 4 to one end of the spool 20 via a shuttle valve 21, and provides a spring 23 at the other end of the spool 20, and a pilot from a remote control valve 24. leading to pressure.

The remote control valve 24 consists of an operating lever 25 and variable pressure reducing valves 26, 27, 28 operated by the operating lever, and the primary ports of the variable pressure reducing valves 26, 27, 28 are connected to a servo pump 30 through a passage 29, The secondary boat of the variable pressure reducing valve 26.27 is connected by a passage 31.32 to the rod chamber 33.34 of the cylinder in which the pilot piston 16.17 of the servo valve 10 is inserted, and the passages 31 and 32 are connected to the shuttle valve 35. Connect through this shuttle valve 35
The secondary boat is one of the shuttle valves 36.
Next is connected to Bonito. The secondary boat of the variable pressure reducing valve 28 is connected to the other primary boat of the shuttle valve 36 by a passage 37, and the secondary boat of the shuttle valve 36 is led to the end of the spool 20 on the spring 23 side of the cut-off valve 11. There is.

Since this embodiment has the above-described configuration, when the operating lever 25 is operated from the neutral position to the right, the variable pressure reducing valve 2
6 is actuated to connect the passages 29 and 31, and the operation lever 25
The pilot pressure Pi proportional to the operating angle of the servo valve 10
The spool 13 assumes the right position and the cutoff valve 11 assumes the right position. As a result, the servo pressure Ps from the servo pump 12 is guided to the liquid chamber 8 via the cutoff valve 11 and the servo valve 10.
As a result of the liquid chamber 9 communicating with the tank 38, the servo piston 7
moves to the right to increase the pump tilt angle, and pressurized oil is discharged from the variable displacement pump 5 to the main flow path 2. Since the hydraulic motor 1 is not accelerated immediately due to the inertial force of the inertial body attached to it, a hydraulic pressure Pd is generated in the main flow path 2, and this hydraulic pressure Pd acts on the spool 20 of the cut-off valve 11, but the spring 23
Since the pressing force on the side is strong, the position of the cutoff valve 11 remains unchanged and the servo pressure is guided to the liquid chamber 8, so the hydraulic motor 1 is accelerated. On the other hand, since the sleeve 18 is linked to the servo piston 7 via the feedback lever 19, when the operating lever 25 is stopped, the pilot pressure becomes constant and when the sleeve 18 moves to the spool 13 position corresponding to the pilot pressure, the liquid chamber im on 8,9
The through hole of the sliding sleeve 18 is closed by the land of the spool 13 and the servo piston 7 is hydraulically locked, so that the discharge amount of the variable displacement pump 4 is constant and the hydraulic motor 1
is a steady rotation.

Here, when the operating lever 25 is returned to the neutral position, the pilot pressure Pi becomes zero, but the cutoff valve 11 is held in its position by the spring 23, and the spool 13 of the servo valve lO is held in the neutral position by the neutral return springs 14 and 15. Back to sleeve 18
If it does not follow the spool 13. Therefore, the servo pressure Ps
is guided to the liquid chamber 9, and the liquid chamber 8 communicates with the tank 3. The servo piston 7 begins to return to the neutral side and the pump discharge rate decreases, while the hydraulic motor 1 stops rotating due to the inertial force of the inertial body. In order to continue, brake pressure P is applied to the main flow path 3.
d' occurs. This brake pressure Pd' acts on the spool 20 through the shuttle valve 21, but since the force of the spring 23 is weak compared to the hydraulic pressure, the spool 20 is switched to position a even if a very low brake pressure Pd' is generated. , the liquid chambers 9 and 8 of the servo cylinder 6 communicate with the tank 38, and the servo piston 7 is released from the hydraulic pressure. Therefore, the inertial body continues to rotate freely due to inertial force, resulting in a so-called neutral flow state.

To stop the inertial body during free rotation, use the operating lever 35.
to the brake position. As a result, the variable pressure reducing valve 28 is activated, and the passages 29 and 37 are connected to each other, and the servo pump 30 is connected.
The pilot pressure Pi from the shuttle valve 36 acts on the spool 20 of the cut-off valve 11 to switch the cut-off valve 11 to the position. In this case, the spool 13 of the servo valve 10 is in the neutral position, but the sleeve 18 is deviated from the neutral position, leading the servo pressure to the liquid chamber 9 and communicating the liquid chamber 8 with the tank 38.
8 moves to the neutral side and the pump discharge amount decreases.

When the servo piston 7 and the sleeve reach the neutral position, the pump discharge amount becomes zero and the servo piston 7 is hydraulically locked by the servo valve 10, so that the hydraulic motor 1 stops operating.

If the operating lever 25 is moved to the brake position, the pilot pressure is guided to the cut-off valve 11, so even if an external force is applied to the hydraulic motor 1 and counteracting motor holding pressure acts on the cut-off valve 11, it is cut off. The off valve 11 takes its position and guides the servo pressure to the servo valve 10.On the other hand, when the motor holding pressure acts on the pump 4 and moves the servo piston 7, for example, to the right, the sleeve 18 moves to the left. Since the spool 13 is in the neutral position, the servo pressure is
and pushes the servo piston 7 back to the neutral position. Therefore, the hydraulic motor l at rest is not rotated by external force.

Incidentally, even when the hydraulic motor 1 is controlled by operating the operating lever 25 to the left, the above-mentioned effect can be obtained by simply reversing the rotational direction of the hydraulic motor 1. [Effects of the Invention] As explained above. According to the present invention, the inertial body in the neutral flow state is reliably stopped by moving the operating lever in the neutral position to the brake position, so that the stopping operation can be easily performed.

Moreover, even after the inertial body has stopped, by placing the operating lever in the brake position, the hydraulic motor that is at rest will not be moved by external force, so there will be no accidents and it is extremely safe.

[Brief explanation of the drawing]

FIG. 1 is a hydraulic circuit diagram of an embodiment of the present invention, and FIG. 2 is a hydraulic circuit diagram of a conventional device. 1. Hydraulic motor, 2, 3. Main flow path, 4. Variable displacement star pump, 7. Katana-Boviston, 10. Servo valve,
11...Cut-off valve, 12...-IJ--Hobonpu,
13...Spool, 18...Sleeve, 19...Feet Hasokureha, 23...Spring, 25.45.46...
Shirt]・Le valve, 34・・Distant control valve, 35・・Operation lever.

Claims (1)

[Claims] A hydraulic motor connected to an inertial body, a variable displacement pump connected to the hydraulic motor to form a closed circuit through a main flow path, a servo piston that controls the pump tilt angle, and a servo piston that is controlled by pilot pressure. In an inertial body-driven hydraulic closed circuit including a servo valve that has a spool and a sleeve that interlocks with the servo piston and controls the servo piston by servo pressure guided through the cut-off valve, one end of the spool of the cut-off valve has a variable capacity A spring is installed at the other end to guide the higher pressure of the main flow passages on both sides of the pump, and to control the higher pressure of the brake pilot pressure from the remote control valve and the servo valve control pilot pressure. An inertial body-driven hydraulic closed circuit characterized in that it is designed to be guided.