JPH0122964Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a drive device for a hydraulic motor that constantly rotates in a fixed direction.

An example of a device that uses a hydraulic motor that constantly rotates in a fixed direction is a kneading device for a concrete pump truck. This kneading device has a rotating blade installed in a hopper, and the blade is rotated in a fixed direction by a hydraulic motor to mix concrete. In this kneading device, when the blade rotates in the hopper, pebbles may be caught between the hopper and the blade, causing an overload on the hydraulic motor.

Conventionally, as a drive device for a hydraulic motor that rotates the blades of a kneading device, the one shown in FIG. 1 has been used. In this device, a directional switching valve 2 is arranged between a hydraulic pump P and a tank T, and a hydraulic motor 1, and this directional switching valve is used to move the hydraulic motor 1 in the direction of arrow A (forward rotation direction A) The first switching position 2a to be driven and the direction of arrow B (reverse direction B.)
It has two switching positions, a second switching position 2b, which is driven to the second switching position 2b, and a spring 3a that normally positions the switch in the first switching position 2a, and a lever 3b that operates to the second switching position 2b against this spring 3a. It is something.

In this device, if the lever 3b is not operated, the directional switching valve 2 is in the first switching position 2a, and when the hydraulic pump P is driven in this state, the discharge pressure oil is transferred via the directional switching valve 2 and the hydraulic circuit 4a. The oil from the other side of the hydraulic motor 1 flows out to the tank T via the hydraulic circuit 4b and the directional switching valve 2, so that the hydraulic motor 1 rotates in the normal rotation direction A.
Rotate to. If an overload is applied to the hydraulic motor 1 while the hydraulic motor 1 is rotating in the normal rotation direction A (during concrete mixing in the case of a mixing device), the rotation of the hydraulic motor 1 is stopped. At this time, the directional switching valve 2 is operated to the second switching position 2b by the lever 3b, and each of the hydraulic circuits 4a, 4b is switched to the tank T.
and pump P, hydraulic motor 1
drive in reverse direction B, and check when the cause of overload (for example, in the case of a kneading device, remove small stones caught between the hopper and the blade by rotating the blade in reverse direction B). Plan it out,
When the lever 3b is released, the directional control valve 2 is activated by the spring 3a.
As a result, the hydraulic motor 1 is again switched to the first switching position 2a, and the hydraulic motor 1 is driven in the normal rotation direction A again.

When this drive device is used in a kneading device, the hydraulic motor 1 should be operated in the reverse direction B as soon as possible when an overload is applied to the hydraulic motor 1 in order to avoid damage to the blades and rise in oil temperature. Since this is necessary, an operator is required for this purpose.

The technical object of the present invention is to automatically drive the hydraulic motor in the reverse direction for a certain period of time when an overload is applied while the hydraulic motor is being driven in the forward direction.

A technical means for achieving this technical problem is that in a hydraulic motor drive device in which a directional control valve is arranged between a hydraulic motor, a hydraulic pump, and a tank, a first pilot part and a second pilot part are connected to the directional control valve. The directional switching valve is provided with a spring that switches the hydraulic motor to a first switching position for driving the hydraulic motor in the normal rotation direction when the first and second pilot parts are at approximately the same pressure, and the first pilot part is connected to the upstream side of the unloading valve connected to the hydraulic circuit on the supply side when the directional control valve is in the first switching position;
A second pilot section is connected from the upstream side of the unloading valve via a check valve to the downstream side of the free flow of the check valve, and is connected to an accumulator connected to the discharge valve, and It is connected to the pilot part of the valve.

This technical means is such that while the hydraulic motor is rotating in the forward direction, hydraulic pressure is accumulated in the accumulator and the unload valve does not operate, so the first pilot part and the second pilot part are at the same pressure. and the directional control valve is held in the first switching position. and,
When an overload is applied to the hydraulic motor, the unload valve is
When the hydraulic circuit on the supply side of the hydraulic motor is activated and the hydraulic circuit on the supply side of the hydraulic motor is connected to the tank, the first pilot section is connected to the tank, and the hydraulic pressure of the accumulator acts on the second pilot section, causing the directional switching valve to move to the second switching position. Become,
The hydraulic motor is driven in the reverse direction. At the same time, the pressure oil in the accumulator is gradually released into the tank by the release valve, the oil pressure in the accumulator decreases, and when the oil pressure in the second pilot section becomes almost the same as the oil pressure in the first pilot section, the directional control valve is activated. , the hydraulic motor is again switched to the first switching position by the spring and driven in the normal rotation direction.

The present invention equipped with the above technical means has the following unique effects.

The technical problem of the present invention is that the conventional hydraulic motor drive device shown in FIG. An electromagnetic operating section is provided in place of the lever 3b, a pressure switch is provided in the hydraulic circuit 4a, and an off-delay timer is provided which is activated by the output signal of the pressure switch, and the output side of the off-delay timer is connected to the electromagnetic circuit. This can also be achieved by technical means connected to the operating unit. However, according to this technical means, when an overload is applied while the hydraulic motor is being driven in the normal rotation direction, the pressure switch is activated, and an off-delay timer that operates based on the output signal of the pressure switch activates the electromagnetic operation section. This switches the switching valve to the second switching position. Therefore, the hydraulic pump P
is when the directional control valve 2 is at high pressure (due to an overload acting on the hydraulic motor 1).
Since the switching position is switched from the switching position to the second switching position, the supply and discharge of pressure oil to and from the hydraulic motor changes rapidly, which causes a shock to the hydraulic motor.

However, according to the technical means of the present invention, the unloading valve operates and the directional control valve is turned on while the hydraulic pressure acting on the hydraulic circuit on the supply side of the hydraulic motor (hydraulic pump P hydraulic pressure) is kept at a low pressure. Since the first switching position is switched to the second switching position, the hydraulic motor can be smoothly switched from the forward rotation direction to the reverse rotation direction.

Hereinafter, FIGS. 2 to 4 showing an embodiment of the present invention will be described.

In FIG. 2, the hydraulic motor 1 is connected to a hydraulic pump P and a directional control valve 2' (shown in FIG. 3 and described later) connected to a tank T via hydraulic circuits 4a' and 4b'. The directional valve 2' is in the first switching position 2
a' and 2b', and when the first pilot part 5a, the second pilot part 5b, and the first and second pilot parts have almost the same pressure, the directional control valve 2' is
This configuration includes a spring 3a' that holds the switching position 2a'.

Pilot control unit 8 (shown in FIG. 4 and described later)
In this example, a throttle 9 and an unload valve 10 are connected to the hydraulic circuit 4a', and an accumulator 13 is connected between the throttle 9 and the unload valve 10 via a check valve 12. and check valve 12
The unload valve 10, the discharge valve 14, and the spring chamber 25 of the accumulator are all connected to the tank T through the discharge valve 14. The first pilot part 5a of the directional control valve 2' is connected between the throttle 9 and the check valve 12, and the second pilot part 5b is connected between the check valve 12
The pilot valve portion 10a of the unload valve 10 is connected between the accumulator 13 and the check valve 12 via a throttle 24.

The directional control valve 2' shown in FIG. 3 includes a discharge passage 7d connected to a tank T, a supply passage 7c connected to a hydraulic pump P, a load passage 7a connected to a hydraulic circuit 4a', and a load connected to a hydraulic circuit 4b'. A valve body 17 having an inner hole 16 in which each of the passages 7b opens, large diameter portions 18a, 18b, 18c and small diameter portions 19a, 19 that are slidably fitted into the inner hole 16 of this valve body 17.
The end face of this spool 20 is formed by a first pilot part 5a and a second pilot part 5b each having pilot chambers 5a' and 5b' into which the spool 20 is provided. is moved to the left by a spring 3a' provided in the pilot chamber 5a' when the pilot chambers 5a' and 5b' are at approximately the same pressure. When the spool 20 is in the left direction, the small diameter portion 19b connects the load passage 7b to the discharge passage 7d, and the small diameter portion 19a connects the load passage 7b to the discharge passage 7d.
a to the supply passage 7c and the large diameter portion 18
a and 18c cut off the load passage 7b and the supply passage 7c, and the load passage 7a and the discharge passage 7d, respectively.
(Switching position 2a' in Fig. 2) Also, the pilot chamber 5
When a' is connected to the tank T and hydraulic pressure is applied to the pilot chamber 5b', the spool 20 is moved to the right. When the spool 20 is positioned to the right, the small diameter portion 19b connects the load passage 7b to the supply passage 7.
c, the small diameter portion 19a connects the load passage 7a to the discharge passage 7d, and the large diameter portion 18a, 1
8b blocks off the load passage 7a and the supply passage 7c, and between the load passage 7b and the discharge passage 7d (switching position 2b' in FIG. 2). Although not specifically described, the directional switching valve 2' is in the first switching position 2.
When switching from a' to the second switching position 2b', a configuration may be adopted in which the switching position connects the supply passage 7c and the load passages 7a and 7b to the discharge passage 7d. It is also possible to have a configuration that does not have.

The pilot control unit 8, as shown in FIG.
This is a configuration in which a valve body 21, an unload valve 10, and an accumulator 13 are arranged in series.

The valve body 21 has a port P connected to the hydraulic circuit 4a'.
1, a throttle 9, a port P2 connected to the pilot chamber 5a', and a check valve 12. Poppet valve 22 provided
The poppet valve 22 side of the rod 23 is connected to the upstream side of the check valve 12, and the opposite side is connected to the downstream side (open side) of the check valve 12. Yumulator 13
It is configured to connect to the accumulator chamber 27) via a throttle 24. Then, the hydraulic motor 1 becomes overloaded and the pressure downstream of the throttle 9 increases to the poppet valve 22.
When the force exceeds the force of the pressure regulating spring, the poppet valve 22 opens and the pressure on the downstream side of the throttle 9 decreases because it communicates with the spring chamber 25 of the accumulator 13 and the tank T. As a result, the pressure applied to the rod 23 from the downstream side of the check valve 12 through the throttle 24 becomes greater than the pressure at the poppet valve, so the rod 23 moves to the left and presses the poppet valve 22 to maintain the open state. do. As will be described later, when the pressure in the accumulator chamber 27 gradually decreases due to pressure release from the release valve 14 and drops to a constant pressure lower than the opening pressure value of the poppet valve 22, the poppet valve is opened via the rod 23. The valve is closed because the force that holds the valve open becomes smaller than the force of the pressure regulating spring (it has a hysteresis characteristic as the pressure receiving area of the poppet valve <the pressure receiving area of the rod).

The accumulator 13 has a spring chamber 25 equipped with a spring 25a that connects the tank T and presses the piston 26, a piston 26 that is constantly pressed to the right by the spring 25a, and an unload valve that the piston 26 enters into. The accumulator chamber 27 is connected to the downstream side of the check valve 12 via the check valve 10, and the accumulator chamber 27 is connected to the spring chamber by the passage 28 of the piston 26 just before the piston 26 reaches the rightmost end. 25 and is always connected to the spring chamber 25 via the release valve 14. When the hydraulic motor 1 is started and hydraulic pressure is applied to the accumulator chamber 27 through the throttle 9 and the check valve 12, the piston 26 is pushed to the left against the spring 25a and moves to a position where its tip hits the stopper 29. do. At this time, if the opening area of the passage 28 is too large, all the pressure oil flowing into the accumulator chamber 27 through the check valve 12 flows out to the spring chamber 25 and tank T through the passage 28 and the release valve 14, Since the pressure does not rise and the piston 26 does not move to the left, the opening area of the passage 28 is such that during normal operation of the hydraulic motor 1, pressure is accumulated in the accumulator chamber 27 and the piston 26 can move to the left. The area will be designed to a certain extent. When the piston 26 moves to the left, the passage 28 closes, so part of the oil flowing in through the check valve 12 is released into the tank T via the release valve 14, but most of it is stored in the accumulator chamber 27. Therefore, the oil pressure in the accumulator chamber 27 becomes approximately equal to the upstream pressure (load pressure) of the check valve 12. As will be described later, when the hydraulic motor 1 becomes overloaded, the unload valve 10 opens and the upstream pressure of the check valve 12 decreases (becomes no-load pressure), so that pressure is accumulated in the accumulator chamber 27. The pressure oil (the volume of the accumulator chamber 27 is adjusted by the stopper 29) is gradually released into the tank T through the release valve 14, the pressure in the accumulator chamber 27 decreases, and the piston 26 is moved to the right again by the spring 25a. being pushed back towards you. When the piston 26 reaches near the rightmost end, the passage 28 opens, and the pressure in the accumulator chamber 27 drops rapidly, becoming almost equal to the upstream pressure (no-load pressure) of the check valve 12. From the time when the unload valve 10 is opened in this process, the passage 2
8 until the hydraulic motor 1 opens as described later.
Since this time depends on the opening area of the discharge valve 14, the opening area of the discharge valve 14 is designed to match the reverse rotation time of the hydraulic motor 1.

This embodiment of such a configuration operates as follows.

The second directional control valve 2' is in the first switching position 2a'.
When the hydraulic pump P is driven in the state shown in the figure,
The discharge pressure oil is supplied to the directional control valve 2' and the hydraulic circuit 4.
a' to one side of the hydraulic motor 1, and the other oil of the hydraulic motor 1 flows out to the tank T via the hydraulic circuit 4b' and the directional control valve 2', so that the hydraulic motor 1 rotates in the normal direction. Rotate in direction A. At this time, the hydraulic pressure in the hydraulic circuit 4a' increases to the load pressure of the hydraulic motor 1, and this hydraulic pressure is accumulated in the accumulator chamber 27 of the accumulator 13 via the check valve 12. Therefore, in both the first pilot chamber 5a and the second pilot chamber 5b of the directional control valve 2',
Since the load pressure of the hydraulic motor 1 acts, the directional control valve 2' is held in the first switching position 2a by the pressing force of the spring 3a'. When the hydraulic motor 1 is rotating in the normal rotation direction A, an overload is applied and the poppet valve 22 of the unload valve 10 is removed from the valve seat by the hydraulic pressure of the hydraulic circuit 4a'. Since the oil pressure on the upstream side decreases, the rod 23 moves to the left by the oil pressure in the accumulator chamber 27 and presses the poppet valve 22.

When the hydraulic pressure in the hydraulic circuit 4a' decreases due to the operation of the unload valve 10, the hydraulic motor 1 stops, and at the same time, the hydraulic pressure in the first pilot portion 5a also decreases. At this time, the hydraulic pressure at the time when the hydraulic motor 1 is stopped is accumulated in the accumulator chamber 27 of the accumulator 13, so this hydraulic pressure acts on the second pilot part 5b, and the spool of the directional control valve 2' 20
is moved to the right from the position shown in Figure 3, and the second
Switched to switching position 2b'.

Therefore, as the hydraulic motor 1 begins to rotate in the reverse direction B, the pressure oil in the accumulator chamber 27 is gradually released into the tank via the release valve 14.
For a certain period of time determined by the volume of the accumulator chamber 27 and the opening area of the discharge valve 14, high pressure acts on the second pilot portion 5b to maintain the directional control valve 2' in the second switching position 2b'. Therefore, the hydraulic motor 1 is driven in the reverse direction B for the certain period of time. Note that when the hydraulic motor 1 is driven in the reverse direction B, a large amount of oil from the hydraulic motor 1 is discharged into the hydraulic circuit 4a', and a part of it flows into the unload valve 10, but the inflow amount is limited by the throttle 9. Therefore, the unload valve 10 continues its operation regardless of the hydraulic pressure discharged to the hydraulic circuit 4a'.

In this way, when the entire pressure oil in the accumulator chamber 27 flows out to the tank T via the release valve 14, the hydraulic pressure acting on the second pilot part 5b also decreases, so that the pressure oil in the first pilot part 5a and the second pilot part 5b become approximately the same pressure,
The spring 3a' switches the directional switching valve 2' to the first switching position 2a', thereby driving the hydraulic motor 1 in the normal rotation direction A again.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a conventional hydraulic motor drive device, Fig. 2 is a circuit diagram of a hydraulic motor drive device according to an embodiment of the present invention, and Fig. 3 is a cross section of the directional control valve shown in Fig. 2. 4 are cross-sectional views of the pilot control section of FIG. 2. 1... Hydraulic motor, 2, 2'... Directional switching valve,
2a, 2a'...first switching position, 2b, 2b'...second switching position, 3a, 3a'...spring, 4a, 4a',
4b, 4b'...Hydraulic circuit, 8...Pilot control section, 10...Unload valve, 12...Check valve, 1
3... Accumulator, 14... Release valve, P...
...Hydraulic pump, T...tank.

Claims (1)

[Scope of utility model registration request] A first switch which is provided between a hydraulic motor, a hydraulic pump and a tank, and has a first switching position for forward rotation of the hydraulic motor, a second switching position for reverse rotation of the hydraulic motor, a spring for holding the hydraulic motor in the first switching position, and a pilot chamber. a pilot section, and a second pilot section having a pilot chamber operated to the second switching position, wherein the differential pressure between the input pressure of the second pilot section and the input pressure of the first pilot section corresponds to the force of the spring. a directional control valve that is held in the first switching position when the differential pressure is smaller than the force of the spring; and held in the second switching position when the differential pressure is greater than the spring force; An inlet connected to a hydraulic circuit, an outlet connected to the tank, a second pilot part of the directional control valve, and a pilot part connected to an accumulator to be described later, the hydraulic pressure of the inlet is an unload valve that opens when the pressure of the hydraulic motor increases to an overload pressure and closes when the hydraulic pressure of the pilot section decreases to a predetermined pressure from the valve opening pressure of the inlet; upstream of the unload valve; The hydraulic motor is connected to the side via a check valve, and is further connected to the tank via a release valve, and accumulates and increases the pressure of the hydraulic pressure when the hydraulic motor is running in the normal direction, and when the hydraulic motor is running in the reverse direction, it is sent to the tank via the release valve. an accumulator that releases pressure and lowers the pressure; and when the hydraulic motor is in normal rotation and an overload occurs, the unload valve opens and the directional switching valve changes from the first switching position to the first switching position. the hydraulic motor is automatically reversed by the pressure release time of the accumulator, and further, after the pressure release of the accumulator, the directional control valve is switched from the second switching position to the A hydraulic motor drive device that automatically returns the hydraulic motor to normal rotation by automatically switching to a first switching position.