JPH0351523Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The hydraulic control valve device of this invention is used in a hydraulic circuit that starts and stops a high inertial load such as a swing motor of a hydraulic excavator without impact.

<Prior Art> A conventional hydraulic control valve device of this type is disclosed in Japanese Patent Application Laid-open No. 79901/1983. This technique uses a counterbalance valve as a means to prevent impact when starting or stopping a hydraulic motor. Since this counterbalance valve is switched by its own hydraulic pressure, it has problems such as being easily a cause of hunting in the hydraulic system and not being able to sufficiently cushion the shock when starting the hydraulic motor. Ta. For this reason, the inventor of this invention previously devised a hydraulic control device as shown in FIGS. 3 to 9. This will be explained next.

In Figures 3 to 6, 1 is a pilot valve;
2 is a directional control valve, 3 is a crossover relief valve section, and 4a, 4a' are flow rate control valves.

As shown in FIG. 3, the pilot valve 1 is a set of two pressure reducing valves 1c and 1c', and has a handle 1a, which reduces pressure from a pilot pressure oil source 1b according to its operation. Oil pilot circuit 2c, 2
Discharge to either side of c′. Pilot circuit 2
2c and 2c' are connected to spring chambers 2b and 2b' of pilot portions 2a and 2a' of the directional control valve 2 through flow control valves 4a and 4a', respectively. In the figure, P ₁ and P ₂ are ports to which pilot circuits 2c and 2c' are connected, respectively.

The directional control valve 2 has pilot parts 2a and 2a', and the spool 5 is moved from a neutral state to the right or left in the figure by a spring 2d' or 2d by pressure oil supplied to the pilot parts 2a and 2a'. The movement connects the port P ₃ connected to the pressure oil source P to either port M ₁ or M ₂ connected to the hydraulic motor 6, and also connects the port P 3 connected to the hydraulic oil source P to either port M ₁ or M _{2 connected to the hydraulic motor 6} . The port T ₁ or T ₂ connected to the tank T is connected to the other side of the tank T.

At that connection, the spool 5 moves a distance S ₁ to the right.
(See Figure 4) When moving, ports T ₁ and M ₁ will be connected, and when moving further, the distance S ₂ (fourth port) will be connected.
(see figure), ports P ₃ and M ₂ will be connected. The connection between ports T ₁ and M ₁ is shown in Figure 7a,
As shown in the enlarged view in FIG. 9, this is done by the aperture _e1 formed by the notch 5a formed in the spool 5, and as the moving distance increases, the opening area gradually increases as shown by the curve c in FIG. increase The connection between ports P ₃ and M ₂ is achieved by a restriction e 2 ′ formed by a notch 5 b ′ and a small hole ₅ d ′ formed in the spool 5, as shown enlarged in FIGS. 8a and 8 b. As the moving distance increases, the opening area rapidly increases as shown by curve D in FIG. Similarly, when the spool 5 moves to the left, when it moves a distance S ₁ , ports T ₂ and M ₂
becomes connected, and when the distance S ₂ is reached, the port
P ₃ and M ₁ are now connected, and the aperture area has also been reduced.
e ₁ ' and aperture e ₂ increase as shown by curves C and D, respectively.

The crossover relief valve section 3 is as shown in FIGS. 3 and 5, and only serves to prevent overload from acting on the hydraulic motor 6.
Overload relief valves 3a and 3b are port _M1
and _M2 are connected in parallel with opposite directions. If a large load is applied to the hydraulic motor 6 while pressure oil is being supplied from port M ₂ to the hydraulic motor 6, and the oil pressure in port M ₂ exceeds the set value of the relief valve 3a, part of the pressure oil in port M ₂ flows into port _M1 via relief valve 3a to prevent overload from acting on hydraulic motor 6. When the rotation of the hydraulic motor 6 is reversed, the relief valve 3b acts.

As shown enlarged in FIG. 6, the flow control valves 4a and 4a' have a small valve 12 equipped with a metering orifice 11 slidably fitted into the lower part of a casing 10 having a port _P1 . Pressure oil flows from the metering orifice 11 to the spring chamber 13 and to the throttle hole 14.
When flowing out to port _P1 through the metering orifice 11, the pressure before and after the metering orifice 11 is kept constant by the variable throttle formed by the tip of the small valve 12 and the throttle hole 14, and the pressure in the pilot parts 2a, 2a' is kept constant. The outflow of pressure oil from the chambers 2b, _2b ' to the ports P1, _P2 is set to a value corresponding to the opening area of the metering orifice 11.

This conventional hydraulic control valve device has a pilot valve 1
When the handle 1a is suddenly operated to the left in the figure, pilot pressure oil is supplied from the pilot valve 1 to the pilot chamber 2b of the pilot section 2a through the pilot circuit 2c, port P ₁ and flow control valve 4a. . The spool 5 of the directional control valve 2 moves to the right in the figure due to the pressing force of the pilot pressure oil, and as a result, the oil in the pilot chamber 2b' of the pilot section 2a' on the opposite side is controlled by the flow rate control valve 4a'. It is discharged from the tank from the pressure reducing valve 1c' of the pilot valve 1.
Therefore, the spool 5 of the directional switching valve 2 moves to the right at a constant speed and switches, regardless of sudden operation of the pilot valve 1. In addition, in the switching, as mentioned above, ports M ₁ and T ₁ are first connected, then ports P ₃ and M ₂ are connected, and the cross-sectional area of the opening changes as shown in Figure 9. Therefore, when the spool 5 moves a distance _S2 , pressure oil from the hydraulic source P is supplied to the hydraulic motor 6. From this point on, the hydraulic motor 6 begins to accelerate, but the speed remains according to the curve D until the spool 5 reaches the position S ₂ '. When the spool 5 is further moved, the acceleration of the hydraulic motor 6 becomes a speed corresponding to the curve C. In addition, the handle 1 of the pilot valve 1
When a is suddenly operated to the right from the neutral position in the figure, the direction of rotation of the hydraulic motor 6 is reversed, but its acceleration has a value according to curve C. Also, if the handle 1a of the pilot valve 1 is suddenly returned from the operating position to the neutral position, the spool 5 will be moved by the spring 2d' or 2.
d, and its moving speed is controlled by the flow rate control valve 4a or 4a', so it acts in the same way.
Note that after boats M ₁ and T ₁ are connected, port P ₃
The reason for connecting boats M 1 and M ₂ is that first, by connecting boats M ₁ and T ₁ , the hydraulic pressure of the discharge side circuit, which is closed, is set to tank pressure, and then boats P ₃ and M Since the hydraulic motor 6 is driven by connecting the hydraulic motor 6 to the hydraulic motor ₂ , this prevents a shock when the hydraulic motor 6 is started. Furthermore, when the hydraulic motor 6 is stopped, the connection between the boats P ₃ and M ₂ is cut off, and then the boats M ₁ and T ₁ are cut off, thereby sealing the hydraulic pressure in the discharge side circuit. This is to prevent the hydraulic motor 6 from swinging back when it is stopped.

Therefore, even if the pilot valve 1 is suddenly operated, the hydraulic motor 6 can be properly accelerated without any shock.

<Problems to be solved by the invention> In the conventional hydraulic control valve device described above, when the hydraulic motor is stopped, the pilot valve is operated so that the directional control valve changes from the switching position to the neutral position, and then the hydraulic motor is turned off. There is a problem that there is a time delay before it stops. That is, as explained in FIG. 9, the conventional technology makes the change in the opening area on the discharge side of the hydraulic motor smaller than the change in the opening area on the supply side of the hydraulic motor, and also keeps the moving speed of the spool constant. Therefore, even when the hydraulic motor is stopped, the exhaust pressure is similarly controlled to apply a braking force to the hydraulic motor. However, in order to increase the exhaust pressure to apply braking force to the hydraulic motor, the connection between the hydraulic motor and the tank needs to be sufficiently tightened.
Since the moving speed of the spool is kept constant, even if the directional control valve is operated to the neutral position while the hydraulic motor is rotating, the discharge side of the hydraulic motor is sufficiently throttled and a braking force is applied to the hydraulic motor. By the time the spool is in the switching position in Figure 9, it has moved a distance S ₄ from the neutral position, so the distance S ₃ from which the braking force is generated is from S ₄ .
Since the movement to the position is also at a constant speed, it takes a relatively long time and is accompanied by a time delay.

<Means for solving the problem> The means of this invention is to arrange a hydraulic pilot type directional control valve between the hydraulic power source and the hydraulic motor, and to install a hydraulic pilot type directional control valve between the pilot chamber of the directional control valve and the pilot valve. A flow control valve is provided for controlling the amount of discharge from the pilot chamber to the pilot valve so as to keep the moving speed of the spool of the directional control valve constant, and the spool connects the supply side of the hydraulic motor to the hydraulic power source. When returning from the switching position where the discharge side of the hydraulic motor is connected to the tank to the neutral position where the supply and discharge sides of the hydraulic motor are cut off from both the tank and the hydraulic source,
The passage from the hydraulic source to the hydraulic motor is cut off earlier than the passage from the hydraulic motor to the tank, and the discharge side of the hydraulic motor is connected to the tank until near the neutral position of the return movement of the spool. In a hydraulic control valve device configured such that an opening area controlled by a spool of a passage connecting a supply side of a hydraulic motor and a hydraulic power source is larger than an opening area controlled by a spool of a passage connecting a hydraulic motor, the spool is When going from the switching position to the neutral position, the pilot chamber on the moving direction side is communicated with the pilot valve until the spool reaches a position where it forms a restriction on the exhaust pressure side of the hydraulic motor, A passage is provided in the main body that is closed by the movement of the pool, and the restriction on the movement speed until the pool reaches the position where it forms a restriction on the exhaust pressure side of the hydraulic motor is removed, and the subsequent movement of the pool is The feature is that the speed is limited.

<Function> When the spool moves in a predetermined direction in response to a stop command while the directional control valve is in the switching state, the passageway in the means connects the upstream and downstream sides of the flow rate control valve to the pilot chamber at the start of the movement. The communication state continues until the position (S ₃ in Fig. 9) where the exhaust pressure restriction of the hydraulic motor is formed during the spool movement, so during that time the flow control valve is in a state where its variable restriction is opened. This results in rapid movement of the spool. After that, the passage is closed, the flow rate control valve controls oil leakage from the pilot chamber, and the spool returns to the neutral position at a constant speed.

<Example> This example is an improvement on the conventional hydraulic control valve device explained using FIGS. 3 to 9, and the difference from the conventional one is as shown in FIG. This is because passages 20a and 20a' are provided. Since other points are the same as the conventional one, the same parts are designated by the same reference numerals and the explanation will be omitted.

The passages 20a, 20a' are provided by providing grooves 21a, 21a' in the inner hole through which the end of the spool 5 is inserted, and connecting the grooves with the downstream side of the flow control valves 4a, 4a'.

FIG. 1 shows the directional control valve 2 in a neutral state, and FIG. 2 shows a partially enlarged view of the state in which the spool 5 is in the switching position moved to the right in FIG. In the state shown in FIG. 2, ports P ₃ and M ₂ are connected, and ports M ₁ and T ₁ are connected, so the hydraulic motor 6 is rotating in a predetermined direction. Also,
The shoulder 5a at the left end of the spool 5 is located on the right side of the groove 21a, and the front and back of the metering orifice 11 of the flow control valve 4a are connected by the groove 21a, the pilot chamber 2b, and the passage 20a. In this state, the throttle hole 14 is fully open. From this state shown in Figure 2,
When the handle 1a of the pilot valve 1 is returned to the neutral position, the pilot chamber 2b of the pilot section 2a opens.
is connected to tank T at reduced pressure 1c. Therefore, the spool 5 is pressed to the left by the spring 2d' of the pilot chamber 2b'. At this time, the throttle hole 1 of the flow control valve 4a
4 is fully open, the spool 5 rapidly moves to the position where the shoulder 5a at the left end closes the groove 21a (from S ₄ to S ₅ ). Since the passage 20a is closed when the groove 21a is closed, the pressure oil flowing out from the pilot chamber 2b is controlled by the flow rate control valve 4a, and the spool 5 slowly moves to the neutral position.

Note that when the spool 5 returns to the neutral position from the switching position opposite to the above, it similarly moves in the opposite direction. Also, when the spool 5 moves from the neutral position to the switching position, it starts out slowly at a constant speed and then moves rapidly in the middle, but before the speed changes, the hydraulic motor starts smoothly. do.

<Effects of the invention> The hydraulic control valve device of this invention can be used in the hydraulic circuit of the swing motor of a hydraulic excavator, which has a large inertial load, and can be used to effectively brake when stopping without impairing the smooth characteristics when starting. The time delay before starting can be minimized. Since most of the time required from giving a stop command to stopping can be used as deceleration time, if the time required is the same as in the conventional system, the time required for the spool to move at a speed controlled by the flow rate control valve is used as deceleration time. Since it is possible to increase the number of spools, the constant moving speed of the spool can be slowed down to reduce the shock when stopping.

[Brief explanation of the drawing]

Figure 1 is a sectional view of the main parts of the circuit configuration and the valve used in the embodiment of this invention, and Figure 2 is the first valve in a different state.
Fig. 3 is a sectional view of the circuit configuration of a conventional hydraulic control valve device and the main parts of the valve used, Fig. 4 is an enlarged cross-sectional view taken along line A-A in Fig. 3, and Fig. 5 is a partially enlarged view of the figure. Third
6 is an enlarged sectional view of the flow rate control valves 4a, 4a' of FIG. 3, and _FIG . is a cross-sectional view, b is a plan view of a, FIG. 8 shows a portion forming the aperture e ₂ ' of the spool 5 in FIG. 3, and a is a cross-sectional view.
b is a plan view of a, and Fig. 9 shows the changing state of the opening area of the aperture e ₁ (or e ₁ ′) and e ₂ ′ (or e ₂ ) with respect to the moving distance of the spool of the directional control valve in Fig. 3. This is a graph showing. 1... Pilot valve, 2... Directional switching valve, 3...
...Crossover relief valve, 4a, 4a'...Flow control valve, P, 1b...Hydraulic power source, P1, _{P2 ...} Port (pilot section connection), _P3 ...Port (hydraulic power source connection), 2a , 2b...Pilot part, 5...Spool (direction valve), _T1 , _T2 ...Port (tank connection), 6...Hydraulic motor, _M1 , _M2 ...Port (hydraulic motor connection) , e ₁ , e ₁ ′, e ₂ , e ₂ ′...
Aperture, 20a, 20a'... Passage, 21a, 21
a'...Groove, 5a, 5a'...Shoulder at the end of the spool.

Claims (1)

[Claims for Utility Model Registration] A hydraulic pilot type directional control valve is disposed between a hydraulic power source and a hydraulic motor, and a spool of the directional control valve is moved between a pilot chamber of the directional control valve and the pilot valve. A flow control valve is provided to control the amount of discharge from the pilot chamber to the pilot valve so as to maintain a constant speed, and the spool connects the supply side of the hydraulic motor to the hydraulic power source and the discharge side thereof to a tank. When returning from the switching position where the supply and discharge sides of the hydraulic motor are cut off from both the tank and the hydraulic power source, the path from the hydraulic source to the hydraulic motor is cut off earlier than the path from the hydraulic motor to the tank. In addition, until the return movement of the spool near the neutral position, the opening area controlled by the spool of the passage connecting the discharge side of the hydraulic motor and the tank is smaller than the opening area between the supply side of the hydraulic motor and the hydraulic source. In a hydraulic control valve device configured such that an opening area controlled by a spool of a passage connecting the spool is increased, when the spool moves from its switching position to a neutral position, the spool throttles toward the exhaust pressure side of the hydraulic motor. The main body is provided with a passage which communicates the pilot chamber on the side in the direction of movement with the pilot valve until the spool reaches a position where the hydraulic motor A hydraulic control valve device, characterized in that the restriction on the speed of movement of the spool until reaching a position where a throttle is formed on the pressure side is lifted, and the speed of movement of the spool thereafter is limited.