JPH0244964B2 - SEIGYOBENSOCHI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control valve device for construction machinery and the like, and particularly to a control valve device for controlling the swing, arm, etc. of a hydraulic excavator.

In general, in a hydraulic excavator, it is desirable to perform multiple operations of each actuator during excavation work in order to improve work efficiency or perform accurate work.

However, in the conventional hydraulic circuit of a typical hydraulic excavator, the swing switching valve and the arm switching valve are configured in parallel circuits, so when the swing and arm are operated simultaneously, the load on the arm is light (arm cylinder extension). In the case of 2), the pump pressure did not rise to the pressure required for swinging, so swinging operation became impossible, and when operating the arm while pressing the bucket against the wall, the pushing force of the swing motor was insufficient. .

In order to solve this drawback, a control valve device that controls the swing and arm of a hydraulic excavator has an arm spool and a swing spool that control the arm cylinder and swing motor, respectively, in the valve body of the control valve. A variable flow diversion valve is provided on the upstream side of the swing spool to control the amount of oil supplied from the swing spool to the swing motor, and excess oil in the swing motor is diverted to the arm spool to be supplied to the swing motor. There is a type that operates the arm while giving priority to oil amount and pressure.

In such a control valve device, when the swing spool is switched, the amount of oil supplied from the pump to the swing motor is not affected by the load urging the swing motor.
The necessary amount of oil is supplied to the swing motor by the metering notch cut into the swing spool, and the amount of oil other than the amount required for the swing motor flows to the arm spool, allowing simultaneous operation of the swing motor and arm cylinder. becomes.

However, normally, in the work called ditch digging, the arm excavates by driving a swing motor and pressing a bucket, etc. connected to the arm against the wall of the ditch, so that the wall surface does not slope. Only pressure is required to compensate for the reaction force during excavation, and almost no flow rate is required.

However, the variable flow diverter valve has a structure in which the flow rate determined by the opening area of the metering notch provided on the swing spool flows into the swing motor, and then the excess oil flows to the arm spool. When rotation of the swing motor is prevented, the pump pressure reaches the swing motor relief pressure, and the amount of relieved oil reaches the flow rate determined by the opening area of the metering notch provided on the swing spool. Excess oil flows into the rear arm spool and the arm cylinder performs excavation work.

In such excavation work, the swing relief setting pressure of the relief valve for the swing motor is adjusted to a considerably high pressure in order to increase the acceleration speed during the swing operation of the swing motor alone and at startup in order to improve efficiency. (Normally around 200 kg/cm ² ) When excavating the ditch in this adjusted state, the pump pressure will rise to the swing relief pressure as described above.

However, when excavating side ditches, as mentioned above, the pressing force of the arm against the wall surface is sufficient to compensate for the reaction force from the wall surface due to arm excavation (usually 100
Kg/cm ² ), and not only does the relief pressure for the swing motor rise to the swing relief pressure, but also the consumption of a large amount of flow by the relief valve generates heat and noise, or causes an extremely large amount of pressure. This causes significant energy loss.

The present invention was conceived in view of these points,
The valve body of the control valve that controls the swing and arm of the hydraulic excavator has an arm spool and a swing spool that control the arm cylinder and swing motor, respectively, and the swing spool supplies power to the swing motor on the upstream side of the swing spool. In a control valve device having a variable flow divider valve that controls the amount of oil that is
A relief valve is provided to unload the variable flow diverter valve, and the oil chamber of the relief valve is provided to communicate and shut off the tank to the tank.It is switched in conjunction with the arm spool, and it communicates at the position during excavation work and at other positions. This invention provides a control valve device characterized in that it is provided with a selector valve that shuts off the flow at the center, and a circuit that communicates the divided flow of the variable flow dividing valve with the center bypass passage downstream of the swirling spool.

Embodiments of the present invention will be explained in detail below with reference to FIGS. 1 to 3 showing embodiments. 1 is a control valve device, 2 is a valve body of the control valve device, and the valve body 2 has an arm spool 6 that controls the arm cylinder 3, a boom spool 7 that controls the boom cylinder, and a swing motor 5. A turning spool 8 and a variable flow dividing valve 9 provided upstream of the turning spool 8 are installed. The turning spool 8 is formed with metering notches 23a and 23b.

The variable flow dividing valve 9 includes a spool 28 slidably mounted on the valve body 2, a relief cap 29 and a cap 30 that are screwed onto the valve body 2 in a fluid-tight manner.
The main components are a spring 37 fitted between the spool 28 and the relief cap 29 to press the spool 28, and a relief valve 38 attached to the relief cap 29.

10 is an inlet port connected to the pump P and formed in the valve body 2, and 11 is an outlet port connected to the tank T and formed in the valve body 2. Reference numeral 12 denotes a center bypass passage (hereinafter simply referred to as a bypass passage) formed in the valve body 2, which communicates the inlet port 10 and the outlet port 11 when the spools 6 to 8 are in the neutral position. 13a and 13b are side passages that communicate with the inlet port 10 via the variable flow dividing valve 9;
a communicates with the annular chamber 17a through a second control chamber 32 formed in the spool 28 and an axial passage 36 bored in the spool 28, and a side passage 13b is connected to the spool 28 of the variable flow divider valve 9 on one side and for turning on the other side. It communicates with a bypass passage 12 on the downstream side of the spool 8. Reference numeral 14 is a return passage for the spools 6 to 8, which communicates with the tank T. 15 and 16 are ports communicating with a pipe line connected to the swing motor 5. 1
7 and 18 are hydraulic pressure chambers communicating with the annular chamber 17a;
Ports 9 and 20 communicate with a pipe line connected to the arm cylinder 3, and hydraulic chambers 21 and 22 communicate with the bypass passage 12 via a check valve 51.

The spool 28 and the relief cap 29
A first control chamber 31 formed therebetween is connected to the ports 15, 16 via a passage 35 provided with a throttle 33 and a shuttle valve 34. The spool 28 is controlled to a predetermined position by a pressure difference between the first and second control chambers 31 and 32 and by a spring 37.
The relief valve 38 has a spring 42 attached to a drain oil chamber 40 formed between a relief cap 29 and a cap 27 screwed onto the relief cap 29.
Then, the shaft portion is inserted into the spring 42, the shoulder portion is provided to protrude from the spring 42, and the tip of the conical surface is inserted into the first control chamber 31.
It has a poppet 43 that fits into a passage 39 that communicates between the first control chamber 3 and the drain oil chamber 40.
1 pressure is the maximum allowable value (spring 4 of relief valve 38
When the pressure reaches a value equal to or greater than the set pressure in 2), the pressure oil in the control chamber 31 resists the spring 42 to a selector valve 46 provided in the cap 27, which will be described later.
The water flows into a drain pipe 41 that communicates with the water.

The selector valve 46 includes a valve body 44 attached to the valve body 2 and into which the arm spool 6 is slidably inserted;
A pair of sleeves 45 whose shoulders engage with the arm spool 6 and are loosely fitted into the arm spool 6 and are attached to the valve body 44, and a spring 47 inserted into the outer periphery of the sleeves 45, 45 and a spring 47, the arm spool 6 is held in a neutral position. A passage 49 is provided in the valve body 44 and connected to the return passage 14, and communicates with an annular chamber 50 provided in the valve body 44. 48 is the valve body 44
The annular chamber 48 and 50 are connected to the drain conduit 41 described above, and the annular chambers 48 and 50 are communicated with each other and shut off when the arm spool 6 moves leftward or rightward.

Next, the operation of the present invention will be explained. First, when the arm spool 6, the boom spool 7, and the swing spool 8 are in the neutral position shown, the metering notches 23a, 23 of the swing spool 8 are
Since there is no pressure difference between the upstream and downstream sides of b, the spool 28 of the variable flow dividing valve 9 is in the position shown in the figure under the pressure of the spring 37, and the pressure oil from the pump P passes through the inlet port 10 and the side passage 13a. It is discharged into the tank T from the outlet port 11 via the bypass passage 12.

Now, when the turning spool 8 is switched from the neutral position shown in the figure to the left position, the central land of the spool 8 connects the side passage 13a and the bypass passage 12 on the arm side.
is closed, and the pressure oil from the pump P flows through the side passage 13a,
The oil is supplied to the supply side of the swing motor 5 via the annular chamber 17a, the hydraulic pressure chamber 18, and the port 16, while the return oil of the swing motor 5 is discharged from the outlet port 11 to the tank T via the port 15 and the return passage 14. Therefore, the swing motor 5 rotates.

Here, the flow rate flowing into the swing motor 5 is the hydraulic pressure chamber 1
8, passes through a metering notch 23b provided on the turning spool 8 and reaches the port 16, but a pressure difference occurs between the upper and downstream sides due to the opening area of the metering notch 23b. The upstream pressure goes to the second control chamber 32, and the downstream pressure goes to the first control chamber 3.
1 through the shuttle valve 34, passage 35, and throttle 33, the force due to this pressure difference is
When the pressure exceeds the set pressure of the spring 37, the spool 28 of the variable flow dividing valve 9 is pushed to the left, and the passage 1
0 and the passage 13a, and reduce the flow rate from the side passage 13a to the annular chamber 17a to the hydraulic pressure chamber 18 to the port 16, and at the same time, communicate the passage 10 and the side passage 13b, so that the pressure oil is transferred to the arm spool 6 side. supply.

On the other hand, due to the force of the spring 37, the metering notch 2
When the force on the spool 28 due to the pressure difference between the upstream and downstream sides of 3b (23a) is small, the spool 28 is pushed back by the spring 37 and acts to supply flow to the swirling spool 8. The supply flow rate is determined by the opening area of the metering notch 23b (23a) regardless of the load on the swing motor 5, and excess oil in the swing spool 8 flows toward the arm spool 6.

Furthermore, a relief valve 3 communicating with the first control chamber 31
The set pressure of 8 is determined by the swing relief valve 5 as described later.
However, as mentioned above, the drain oil chamber 40 of the relief 38 is in the tank 14 when the arm spool 6 is in the neutral position (or when the arm cylinder 3 is operated in the direction of contraction). It does not work because it is not connected to the

Note that when the arm spool 6 is switched alone from the neutral position shown in the figure to the left position, the pressure oil of the pump P is supplied to the arm cylinder 3 via the bypass passage 12 and the hydraulic pressure chamber 20, and the arm Activate.

Next, when excavating a side ditch by pressing a bucket belt, etc. connected to the arm against the wall surface of the ditch, the swinging spool 8 is operated to press the bucket belt, etc. against the wall surface. is blocked by the wall surface, the swing motor 5 does not rotate, and the pressure oil from the pump P does not flow to the port 16 via the side passage 13a and the hydraulic pressure chamber 18, so the metering notches 23a and 23b Since there is no pressure difference, and also no pressure difference acting on the first control chamber 31 and second control chamber 32 of the variable flow dividing valve 9, the spool 28 is pushed by the spring 37 so that its right end is The cap 30 is in a protruding state. For this reason, the pressure on the supply side of the swing motor 5 increases, but at this time, the arm spool 6 is in the left position excavation state, so the annular chambers 48 and 50 are in communication, and the oil chamber 40 of the relief valve 38 is connected to the drain. It is connected to the tank T via the pipe line 41, the annular chambers 48, 50, and the passage 49, and becomes the tank pressure, and the relief valve 38
is now operational. At this time, relief valve 3
8 is set to a considerably lower pressure (100 Kg/cm ² ) than the swing relief valves 55 and 56, and the pressure in the first control chamber 31 is maintained at this set pressure. Note that the throttle 33 is provided to maintain the pressure in the first control chamber 31 at the set pressure of the relief valve 38 and to allow the supply side pressure of the swing motor 5 to exceed the set pressure of the relief valve 38. .

In this state, the pressure in the second control chamber 32 (supply side pressure) is equal to the set pressure of the relief valve 38 + the spring 37.
When the pressure exceeds the set pressure of Hydraulic pressure chamber 2
2. The arm cylinder 3 is supplied to the head side of the arm cylinder 3 through the port 20, and the return oil from the rod side is discharged to the tank T through the port 19 and the return passage 14, so the arm cylinder 3 improves work efficiency during excavation. can be raised sufficiently. Here, since the set pressure of the spring 37 is about 5 to 10 Kg/cm ² , the motor supply side pressure is the set pressure of the relief valve 38 + 5 to 10 Kg/cm ²
Therefore, the set pressures of the relief valves 55 and 56 of the swing motor 5 are comparatively low, and the swing motor 5
It is possible to keep the rising pressure to an extremely low level when the engine is not rotating.

As described above, according to the present invention, the variable flow dividing valve is provided with a relief valve, and the drain circuit of the relief valve is connected to the selector valve interlocked with the arm spool, thereby increasing pressure when the swing motor is not rotating. can be kept extremely low, and since there is no flow consumption due to the swing relief valve, wasted energy consumption can be eliminated, and the operability is the same as that of conventional methods except when the arm cylinder is excavated.

[Brief explanation of drawings]

Fig. 1 is a vertical sectional view showing an embodiment of the present invention, Fig. 2
The figure is a sectional view taken along the - line in FIG. 1, and FIG. 3 is a hydraulic circuit diagram showing FIG. 1 with hydraulic symbols. 1...Control valve device, 2...Valve body, 3...Arm cylinder, 5...Swivel motor, 6...Spool for arm, 7...Spool for boom, 8...Spool for swing, 9...Variable Diversion valve, 10... Inlet port, 11... Outlet port, 12... Bypass passage, 13a, 13b... Side passage, 14... Return passage, 15, 16, 19, 20... Port, 17,
18, 21, 22... Hydraulic pressure chamber, 28... Spool, 29... Relief cap, 27, 30...
Cap, 31... First control room, 32... Second control room, 35, 39, 49... Passage, 36... Axial passage, 37, 42... Spring, 38... Relief valve, 40... Oil chamber, 41...Drain pipe, 43
... Poppet, 44 ... Casing, 45 ... Sleeve, 46 ... Selector valve, 47 ... Spring, 4
8,50...Annular chamber, 51...Check valve, 55,5
6...Swivel relief valve.

Claims (1)

[Claims] 1. An arm spool and a swing spool are provided in the valve body to respectively control an arm cylinder and a swing motor, and a variable valve is provided on the upstream side of the swing spool to control the amount of oil supplied from the swing spool to the swing motor. In a control valve device equipped with a flow divider valve, a relief valve for unloading the variable flow divider valve and a relief valve for communicating/blocking the oil chamber of the relief valve with the tank are provided, and are switched in conjunction with the arm spool, A control valve device comprising: a selector valve that communicates in an operating position during work and shuts off in other positions; and a circuit that communicates the divided flow of the variable flow divider valve to a center bypass passage downstream of the swirling spool. .