JPS6337216B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydraulic circuit for civil engineering and construction machines such as hydraulic excavators, hydraulic crawler cranes, and the like.

[Prior art]

When controlling the speed of an actuator that drives a working device in a civil engineering/construction machine such as a hydraulic excavator, a hydraulic circuit is configured that includes a hydraulic pump and a hydraulic actuator and sets the tilting of the hydraulic pump by a signal from an operating lever. A method for adjusting the discharge amount of the hydraulic pump is known. This method is more suitable for energy saving than the method of controlling the speed of a hydraulic actuator by providing resistance in the hydraulic circuit using a hydraulic control valve. However, when configuring a hydraulic circuit in which the tilting of the hydraulic pump is set by a signal from an operating lever, the hydraulic pump and the hydraulic actuator must correspond on a one-to-one basis. Therefore, for example, in the case of a hydraulic excavator, there are a total of six hydraulic actuators: hydraulic cylinders that drive the boom, arm, and bucket, a swing motor, and left and right travel motors, so six hydraulic pumps are required to correspond to these actuators. We must prepare. Moreover, since different hydraulic actuators require different flow rates of oil, it is necessary to provide various types of hydraulic pumps with different discharge amounts. However, in reality, this is nearly impossible due to space constraints and the need to effectively use the power of the prime mover. Therefore, a hydraulic circuit as shown in FIG. 1 has been proposed by the present inventors.

In FIG. 1, reference numerals 1 to 4 are variable discharge capacity hydraulic pumps, 1a to 4a are discharge capacity changing devices such as swash plates, and 1b to 4b are drive devices (hereinafter referred to as swash plate drive devices). 5 to 10 are actuators of the hydraulic excavator, specifically 5 is an arm cylinder, 6 is a bucket cylinder, 7A and 7B are boom cylinders, 8 is a swing motor of the upper revolving structure,
9 and 10 are left and right running motors. Also, 1
1A, 11B, 12A, 12B, 13A-13
C, 14A, and 14B are ON-OFF type electromagnetic switching valves. Note that for the sake of simplification, the flushing circuit and the charging circuit are not shown.

Each hydraulic pump 1-4 (P1-P4) is connected to each actuator 5-10 by electromagnetic switching valve 11A-14B according to the connection priority order (numbers shown in circles) shown in FIG. In other words, hydraulic pump 1
(P1) is preferentially connected to the swing motor 8 in the first order, and when the swing motor 8 is not driven, the arm
It can be connected to cylinder 5 in the second order.
The same applies to the hydraulic pumps 2 to 4 (P2 to P4) below.
For example, when driving only the boom cylinders 7A and 7B, the hydraulic pump 2 (P2) is not driving the first order arm cylinder 5, so it is connected to the second order boom cylinders 7A and 7B, The hydraulic pump 3 (P3) also does not drive the left travel motor 9 in the first order and the bucket cylinder 6 in the second order, so the boom cylinder 7A in the third order,
Since the hydraulic pump 4 (P4) is not driving the first right travel motor 10, it is connected to the second boom cylinders 7A and 7B. Therefore, the boom cylinders 7A and 7B are driven by three hydraulic pumps 2 to 4 (P2 to P4). In addition, when driving the arm cylinder 5 independently, the hydraulic pumps 1 and 2 are
Driven by (P1, P2). The same applies to other actuators. In this way, the number of hydraulic pumps can be reduced, and actuators with different required flow rates can be driven by small hydraulic pumps of the same capacity.

[Problem to be solved by the invention]

By the way, in a hydraulic excavator configured in this way, when attempting to perform a complex operation, for example, to drive the arm while turning, the hydraulic pump 1 (P1) is connected to the first turning motor 8, and the arm cylinder 5 is connected to the first turning motor 8. It is driven only by the hydraulic pump 2 (P2) in the first order. At this time, even if you want to drive the arm cylinder 5 with the flow rate of two hydraulic pumps, it can only be driven with the flow rate of one hydraulic pump, and the hydraulic pumps 3 and 4 (P3, P4) are idle. The inconvenience of being there will occur.

Furthermore, when trying to drive the bucket cylinder 6 while using the left and right travel motors 9 and 10, the bucket cylinder 6 is driven even though the hydraulic pumps 1 and 2 (P1, P2) are idle. Can not do it.

As mentioned above, in the hydraulic circuit shown in Fig. 1, each hydraulic actuator is connected to only the number of hydraulic pumps that can discharge the maximum flow rate required by that hydraulic actuator, so there is a difference in the number of hydraulic pumps that can discharge the maximum flow rate required by that hydraulic actuator. Despite having a pump, there is a problem in that it cannot drive the intended actuator or cannot drive it at maximum speed.

The present invention has been made in view of this point, and its purpose is to provide a hydraulic circuit for civil engineering and construction machinery that can reduce the number of hydraulic actuators that cannot be driven during complex operations or cannot be driven at the required speed. .

[Means to solve the problem]

To achieve this objective, the present invention comprises a plurality of variable displacement pumps and a plurality of hydraulic actuators driven by the variable displacement pumps, each variable displacement pump having ON-OFF electromagnetic switching. It is possible to separately connect a closed circuit to two or more hydraulic actuators via a valve, and the discharge capacity of each variable displacement pump is set by the operation signal of the operation lever of the hydraulic actuator, and at least one hydraulic actuator can be connected in a closed circuit to two or more hydraulic actuators. In a hydraulic circuit for civil engineering and construction machinery that can be connected simultaneously with a variable discharge capacity pump, a flow rate larger than the maximum flow rate required by this hydraulic actuator can be discharged to at least one of the plurality of hydraulic actuators. a first storage unit that connects a number of variable discharge capacity pumps and stores a connection priority order of each of the variable discharge capacity pumps to each of the hydraulic actuators; a connection of each of the hydraulic actuators to each of the variable discharge capacity hydraulic pumps; a second storage unit that stores the priority order; a third storage unit that stores the number of variable discharge capacity hydraulic pumps that can supply the flow rate necessary for driving each of the hydraulic actuators; a first determining unit that determines the type of hydraulic actuator to be driven; a second determining unit that determines which hydraulic actuator and which variable displacement hydraulic pump are currently connected; the first storage unit; a third determining section that determines a combination of a corresponding hydraulic actuator and a variable discharge capacity hydraulic pump based on the memory of the second storing section, the third storing section and the determination of the first determining section; and the second determining section. and a fourth determining unit that determines the combination of a newly connected hydraulic actuator and variable discharge capacity hydraulic pump based on the determination by the third determining unit, and the variable discharge capacity hydraulic pressure determined by the fourth determining unit. a first output section that outputs a command signal to make the discharge amount of the pump zero; a fourth output section;
a second output unit that outputs a command signal for instructing the driving of the ON-OFF electromagnetic switching valve associated with the hydraulic actuator determined by the determination unit; Priority order and connection determining means including a third output section that outputs a command signal for calculating the discharge amount of the variable discharge capacity hydraulic pump in accordance with the operation signal of the operating lever when the discharge amount becomes zero; pump discharge amount calculation means for calculating the discharge amount of each variable discharge capacity pump based on the signal output from the priority order and connection determination means and the operation signal of the operation lever; and the priority order and connection determination means. The pump is configured to include electromagnetic switching valve switching timing means for outputting a switching signal for the ON-OFF electromagnetic switching valve based on the output signal and the signal output from the pump discharge amount calculation means.

〔Example〕

Hereinafter, the present invention will be explained in detail based on illustrated embodiments.

FIG. 3 shows a hydraulic circuit of a hydraulic excavator according to an embodiment of the present invention. Note that this hydraulic circuit is constructed as a closed circuit, and for the sake of simplification, a flushing circuit and a charging circuit are not shown.

In FIG. 3, 1 to 4 are hydraulic pumps with variable discharge capacity similar to those in FIG. call). 5 to 10 are the hydraulic actuators of the hydraulic shovel, specifically 5 is the arm cylinder, 6 is the bucket cylinder, 7A and 7B are the boom cylinders, 8 is the swing motor of the upper revolving structure, and 9 and 10 are the left and right It is a running motor. Also, 11A to 11C, 12A to 12
D, 13A to 13D, 14A to 14D are ON-
This is an OFF type electromagnetic switching valve that is interposed between the hydraulic pumps 1 to 4 and the hydraulic actuators 5 to 10.
Switch the combination of hydraulic pump and hydraulic actuator by turning ON and OFF.

FIG. 4 is an example of a control device for the hydraulic circuit shown in FIG. 3. This control device is composed of an electronic circuit.

In Fig. 4, 15 to 20 are operating levers that issue operation signals for each actuator, 15 is for the arm cylinder, 16 is for the bucket cylinder,
17 is for the boom cylinder, 18 is for the swing motor, 19 is for the left travel motor, and 20 is for the right travel motor. 1b-4b are swash plate drive devices, 11A-
14D is an electromagnetic switching valve, each corresponding to the one shown in FIG. 21 is a priority and connection determination circuit;
Hydraulic actuators 5 to 1 of hydraulic pumps 1 to 4
0, a second storage section that stores connection priorities of each hydraulic actuator 5 to 10 to each hydraulic pump 1 to 4, and a second storage section that stores connection priority of each hydraulic actuator 5 to 10 to each hydraulic pump 1 to 4; a third storage unit that stores the number of hydraulic pumps that can supply the flow rate necessary for a second determining unit that determines how the hydraulic actuator and which hydraulic pump are currently connected;
a third determining unit that determines the combination of the hydraulic actuator and the hydraulic pump based on the storage in the storage unit, the second storage unit, the third storage unit and the determination by the first determining unit; a fourth determining unit that determines a combination of a newly connected hydraulic actuator and hydraulic pump based on the determination by the determining unit and the third determining unit; and a discharge amount of the hydraulic pump determined by the fourth determining unit. a first output unit that outputs a command signal to make the value zero; and an ON-OFF electromagnetic switching valve 11 for the hydraulic actuator determined by the fourth determination unit.
A~11C, 12A~12D, 13A~13D,
A second output section outputs a command signal for commanding the drive of 14A to 14D, and a fourth determination section determines that when the discharge amount of the hydraulic pump becomes zero, it corresponds to the operation signal of the operation lever. The third output section outputs a command signal for calculating the discharge amount of the hydraulic pump. Reference numeral 24 denotes a pump discharge amount calculation circuit which calculates the discharge amount of each hydraulic pump based on the operating levers 15 to 20, the priority order, and the output of the connection determination circuit 21. Reference numeral 25 denotes a pump discharge rate control circuit which receives the output of the pump discharge rate calculation circuit 24 and controls the swash plate drive devices 1b to 4b to control the discharge rate of the hydraulic pump. Reference numeral 22 designates an electromagnetic switching valve switching timing circuit which receives the outputs of the priority and connection determination circuit and the pump discharge amount control circuit 25, and outputs switching signals for the electromagnetic switching valves so as to minimize switching shocks of the electromagnetic switching valves 11A to 14D. Output. 2
Reference numeral 3 denotes an electromagnetic switching valve drive device which operates the electromagnetic switching valve 11 according to the output signal of the electromagnetic switching valve switching timing circuit 22.
Switch between A to 14D.

Note that FIG. 5 is an explanatory diagram showing an example of the storage contents in the first storage section, second storage section, and third storage section included in the above-mentioned priority order and connection determination circuit 21. The ranking as viewed from the side is stored in the first storage unit, and the ranking as viewed from the pump side from each actuator is stored in the second storage unit, and the column for the name of each actuator is stored in the second storage unit. What is shown in [ ] is the storage content of the third storage section. The contents of these memories will be briefly described below.

In FIG. 5, the numbers in parentheses in the actuator column are the maximum number of hydraulic pumps required for each actuator. The numbers in circles are the priorities for the actuators of each hydraulic pump, as in Fig. 2. For example, hydraulic pump 1 (P1) is given first priority to boom cylinders 7A and 7B, second priority to arm cylinder 5, and priority order to the actuator of each hydraulic pump. - It shows that they are respectively connected to cylinder 6 in the third order. From the actuator side, the hydraulic pump with the highest rank is connected first. The number in parentheses is the priority of hydraulic pumps that are in the same order as the actuator. For example, in arm cylinder 5, pumps 1 and 2
(P1, P2) both have second priority, but pump 2 (P2) has the highest priority, then pump 1 (P1),
Next is Pump 4 (P4), which ranks third, and Pump 3 (P3) which ranks fourth, and other unused hydraulic pumps are connected in order of priority according to the required number. go. The priority order shown in FIG. 5 is an example, and is not necessarily the only one. Needless to say, it is determined by the number of hydraulic pumps required by the hydraulic actuator and the required functions of the machine.

Next, the operation of the control device shown in FIG. 4 will be explained in accordance with the priority order shown in FIG. As an example of the operation, the combined operation of the arm cylinder 5 and the left travel motor 9, the timing chart of which is shown in FIG. 6, will be described.

In Figure 6, time t is plotted on the horizontal axis, (a) is the arm/cylinder operating lever, (b) is each signal of the left travel motor operating lever, (c) is the hydraulic pump 1, and (d) is the hydraulic pump. 2 and (e) respectively show the discharge amount of the hydraulic pump 4, and (f) to (i) show the respective discharge amounts of the electromagnetic switching valves 11B, 12B, 1.
The operations of 2A and 14C are shown respectively.

When the arm operating lever 15 enters the Fu 11 at time to, the first determination section of the priority and connection determination circuit 21 determines that the arm cylinder 5 is about to be driven in accordance with the operating signal of the arm operating lever 15. It is determined. Next, the second determining section of this circuit 21 determines which hydraulic actuator and hydraulic pump are currently connected. what if,
It is now assumed that no actuator is connected to the hydraulic pumps 1 to 4. And this circuit 21
The third determining section determines whether the hydraulic actuator The combination of this and the hydraulic pump is determined.
Now, since the actuator is the arm cylinder 5 and the number of hydraulic pumps required for the arm cylinder 5 is 2 from FIG. 5, the arm cylinder 5 and the hydraulic pressure are It is determined that pump 1 (P1) and hydraulic pump 2 (P2) should be connected. Next, the fourth discrimination section of this circuit 21 discriminates the combination of the newly connected hydraulic actuator and hydraulic pump. It is determined that it is a manufacturing combination. Next, a command signal for zeroing the discharge amount of the hydraulic pumps 1 and 2 is output from the first output section of this circuit 21 to the pump discharge amount calculation circuit, and from the second output section of this circuit 21, a command signal is outputted to the pump discharge amount calculation circuit. A command signal that instructs the switching timing circuit 22 to drive the ON-OFF electromagnetic switching valves 11B and 12B related to the arm cylinder 5 is output. The swash plate drive device 1 is then connected from the discharge amount calculation circuit 24 to the pump discharge amount control circuit 25.
A signal is sent to b and 2b, and in response to this, the discharge amount becomes zero. At this time, a command signal to calculate the discharge amount is output from the third output part of the circuit 21 to the discharge amount calculation circuit 24, and in response to this, the discharge amount calculation circuit 24 responds to the operation signal of the arm operation lever 15. Calculation is performed to obtain the corresponding discharge amount. This calculation result is output to the swash plate drive devices 1b, 2b via the pump discharge amount control circuit 25, thereby increasing the discharge amount of the hydraulic pumps 1, 2. On the other hand, electromagnetic Switching valve switching timing circuit 22
is the electromagnetic switching valve 1 via the electromagnetic switching valve drive circuit 23.
Outputs a drive signal to open 1B and 12B. Therefore, the arm cylinder 5 is the hydraulic pump 1
(P1) and hydraulic pump 2 (P2).

Next, at time t ₁ , the left travel motor control lever 19 is
When entering Fu11, the first determination section of the priority and connection determination circuit 21 determines that the left travel motor 9 is also about to be driven in response to the operation signal of the left travel motor operating lever 15. Next, the second determining section of this circuit determines which hydraulic actuator and hydraulic pump are currently connected. Here, it is determined that the arm cylinder 5 is connected to the hydraulic pump 1 (P1) and the hydraulic pump 2 (P2). Then, the third discrimination section of this circuit 21 discriminates between the stored contents of the first storage section, second storage section, and third storage section shown in FIG. 5 and the first discrimination section described above. Based on this, the differential travel motor 9 and hydraulic pump 2 (P2) should be connected, and the arm cylinder 5 and hydraulic pump Y (P1),
4 (P4) should be connected.
Next, the fourth determining section of this circuit 21 determines the combination of the newly connected hydraulic actuator and hydraulic pump based on the determinations made by the second determining section and the third determining section. Now, left running motor 9
and hydraulic pump 2 (P2), and the combination of arm/cylinder 5 and hydraulic pump 4 (P4) are determined to be new combinations to be connected. Then from the first output of the circuit 21 the hydraulic pump 2
A command signal to return the discharge amount of (P2) and the discharge amount of hydraulic pump 4 (P4) to zero is output to the discharge amount calculation circuit 24, and from the second output part of this circuit 21 to the electromagnetic switching valve switching timing circuit 22. Stops the driving of the ON-OFF electromagnetic switching valve 12B related to the arm cylinder 5, and issues a command signal that instructs the driving of the electromagnetic switching valve 14C, and commands the driving of the ON-OFF electromagnetic switching valve 12A related to the left travel motor 9. A command signal is output. The swash plate drive devices 1b and 2 are then connected from the discharge amount calculation circuit 24 to the pump discharge amount control circuit 25.
A signal is sent to b, and in response to this, the hydraulic pumps 2,
When 4 is closed and the solenoid switching valve 12A is opened, the arm
The cylinder 5 suddenly decelerates, and the left traveling motor 9 suddenly accelerates, producing a large shock. Therefore, after the discharge amount of the hydraulic pump 2 is set to zero via the pump discharge amount calculation circuit 24, control is performed to switch between the electromagnetic switching valves 12B and 12A. The hydraulic pump 4 increases the discharge amount from time _t1 when the discharge amount of the hydraulic pump 2 starts to decrease, so that the speed of the arm cylinder 5 does not change. The electromagnetic switching valve 14C is the hydraulic pump 4
Since the discharge amount of (P4) is zero from the beginning in this case, it becomes open at time _t1 . After that, when the discharge amount of the hydraulic pump 2 becomes zero at time _t1 , the electromagnetic switching valve 12B closes and the electromagnetic switching valve 12A becomes open. A command signal for calculating the discharge amount is output from the third output part of the circuit 21 to the discharge amount calculation circuit 24, and in response to this, the discharge amount calculation circuit operates the arm operation lever 15 and the left traveling motor operation lever 19.
Calculation is performed so that the discharge amount corresponds to each operation signal. As a result, the arm cylinder 5 is connected to the hydraulic pump 1 (P1) and the hydraulic pump 4.
(P4), and the left traveling motor 9 is driven by the hydraulic pump 2 (P2).

The same applies to other cases, for example, when trying to drive the right travel motor 10 while the bucket cylinder 6 is being driven by the hydraulic pump 3 (P3), the bucket cylinder 6 is driven by the hydraulic pump 1 (P1). , it never stops.

The control device shown in FIG. 4 operates as described above. Although this control device is constructed of an electronic circuit here, it may be replaced with a hydraulic circuit or a microcomputer.

According to the present invention, the following effects can be obtained.

(1) Even if a hydraulic pump is taken over by a hydraulic actuator with a higher priority, the target hydraulic actuator can be driven at the desired speed by another hydraulic pump.

(2) The number of hydraulic actuators that cannot be driven during complex operations is reduced.

(3) Useless idle hydraulic pumps are reduced.

(4) When the hydraulic pump is taken over by a hydraulic actuator with a higher priority, the discharge amount of the taken hydraulic pump must be returned to zero and switched, but at that time,
By reducing the discharge amount of the hydraulic pump to zero,
Since the discharge amount of the hydraulic pump which replaces this is increased at the same time, the speed fluctuation of the hydraulic actuator at the time of switching is reduced.

〔Effect of the invention〕

As explained above, according to the present invention, a number of variable discharge capacity pumps capable of discharging a flow rate larger than the maximum flow rate required by this hydraulic actuator are connected to a hydraulic actuator via an ON-OFF type switching valve. During combined operation, even if the hydraulic pump is taken by a hydraulic actuator with a higher connection priority, other idle hydraulic pumps can be connected to drive the desired hydraulic actuator. As a result, compared to a hydraulic circuit in which a hydraulic actuator is connected to only the number of hydraulic pumps capable of discharging the maximum flow rate required by that hydraulic actuator, a hydraulic actuator that cannot be driven during combined operation or cannot be driven at the required speed. can be reduced.

[Brief explanation of the drawing]

Figure 1 is a system diagram of the hydraulic circuit related to the existing proposal, Figure 2
The figure is an explanatory diagram showing an example of the connection priority order between the hydraulic pump and the hydraulic actuator in the same hydraulic circuit, FIG. 3 is a system diagram of the hydraulic circuit according to an embodiment of the present invention, and FIG. 4 is a control device for the same hydraulic circuit. A block diagram showing an example, and FIG. 5 is an explanation showing an example of storage contents in the first storage section, second storage section, and third storage section included in the priority order and connection determination circuit shown in FIG. 4. 6A to 6I are timing charts showing an example of the operation of the control device shown in FIG. 4. 1 to 4...Variable discharge capacity hydraulic pump, 1b to 4
b...Swash plate drive device, 5-10...Hydraulic actuator, 11A-14D...ON-OFF electromagnetic switching valve, 15-20...Operation lever, 21...Priority and connection determination circuit, 22...Solenoid Switching valve switching timing circuit, 23...electromagnetic switching valve drive device,
24... Pump discharge amount calculation circuit, 25... Pump discharge amount control circuit.

Claims (1)

[Claims] 1 comprising a plurality of variable discharge capacity pumps and a plurality of hydraulic actuators driven by these variable discharge capacity pumps, each variable discharge capacity pump having a
It is possible to separately connect a closed circuit to two or more hydraulic actuators via an ON-OFF electromagnetic switching valve, and the discharge capacity of each variable displacement pump is set by the operation signal of the operation lever of the hydraulic actuator, and at least one One hydraulic actuator can be connected to multiple variable displacement pumps at the same time.
In the hydraulic circuit of the construction machine, at least one of the plurality of hydraulic actuators is connected to a number of variable discharge capacity pumps capable of discharging a flow rate larger than the maximum flow rate required by the hydraulic actuator, and a first storage unit that stores connection priorities of each of the variable discharge capacity pumps to each of the hydraulic actuators; a second storage unit that stores connection priorities of each of the hydraulic actuators to each of the variable discharge capacity hydraulic pumps; a third storage unit that stores the number of variable discharge capacity hydraulic pumps capable of supplying the flow rate necessary for driving each hydraulic actuator; and a third storage unit that determines the type of hydraulic actuator to be driven in accordance with the operation signal of the operation lever. a second determination unit that determines which hydraulic actuator and which variable discharge capacity hydraulic pump are currently connected; a memory in the first storage unit, second storage unit, and third storage unit; and a third determining unit that determines the combination of the corresponding hydraulic actuator and variable displacement hydraulic pump based on the determination of the first determining unit, and a third determining unit that determines the combination of the corresponding hydraulic actuator and variable displacement hydraulic pump based on the determination of the second determining unit and the third determining unit. a fourth determining unit that determines a combination of a newly connected hydraulic actuator and a variable discharge capacity hydraulic pump;
a first output unit that outputs a command signal to zero the discharge amount of the variable discharge capacity hydraulic pump determined by the determination unit; and the ON-OFF electromagnetic switching valve related to the hydraulic actuator determined by the fourth determination unit. a second output section that outputs a command signal for instructing the drive of the fourth output section;
A third section for outputting a command signal for calculating the discharge amount of the variable discharge capacity hydraulic pump in response to the operating signal of the operating lever when the discharge amount of the variable discharge capacity hydraulic pump determined by the discrimination section becomes zero. a priority and connection determination means including an output section; a pump discharge for calculating the discharge amount of each variable discharge capacity pump based on the signal output from the priority and connection determination means and the operation signal of the operation lever; an electromagnetic switching valve switching timing for outputting a switching signal for the ON-OFF electromagnetic switching valve based on a signal output from the quantity calculation means, the priority order and connection determination means, and a signal output from the pump discharge amount calculation means; A hydraulic circuit for civil engineering and construction machinery, characterized by comprising means.