JPH0452481Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) This invention utilizes the potential energy accumulated in the actuator, which is loaded with loads such as gravity, as the driving force in construction machinery such as power shovels, loading shovels, and cranes. This invention relates to a hydraulic circuit with an energy regeneration mechanism, which is characterized in that it regenerates energy as energy.

(Conventional technology) To explain the conventional example of a power shovel,
As shown in Fig. 3, a front working device consisting of a boom e, an arm f, a bucket g, etc. is operable by a boom cylinder d and is thrust onto a rotating body b on a traveling vehicle a which is rotated by a rotating motor c. The boom cylinder d is loaded with the weight of the front work equipment and lifts the front work equipment against gravity to operate the front work equipment, and potential energy is constantly accumulated due to the weighted load. be done.

Further, a conventional example of the hydraulic circuit of the boom cylinder and the swing motor will be explained with reference to FIG. 2. Hydraulic pipes 52, 52a, 53 of the actuator 4 (the boom cylinder d) subjected to the weight load W are connected via the switching valve 2 which is switched and controlled, and the actuator 5 (the swing motor It has a structure in which the hydraulic pipes 54a and 54b of c) are connected, and when the operating lever 6 of the control mechanism A is operated to the right in the figure, the secondary pressure of the pressure reducing valve 6b increases, and the pilot pressure of the pilot pipe 56 increases. The switching valve 2 is switched to the function 2c, and the discharge pressure oil of the variable displacement pump 1 is transferred from the discharge pipe 50 to the actuator via the switching valves 3 and 2, the hydraulic pipe 52, the check valve 13a, and the hydraulic pipe 52a. 4 load side chamber 4
The hydraulic oil in the non-load side chamber 4b is discharged to the tank _T1 via the hydraulic pipe 53 and the switching valve 2, and the actuator 4 is expanded against the gravity F, and the gravity F is applied to the load side chamber 4a. Potential energy corresponding to the stroke of the rod 4c against the pressure is accumulated, and when the operating lever 6 is operated to the left in the figure, the secondary pressure of the pressure reducing valve 6a increases, and the pilot pressure in the pilot line 55 increases, causing switching. The valve 2 is switched to the function 2a, the discharge pressure oil of the variable displacement pump 1 is supplied from the hydraulic line 53 side to the non-load side chamber 4b, and the pressure oil in the load side chamber 4a is transferred to the hydraulic line 52.
a, it is discharged to the tank _T1 via the throttle 13b, the hydraulic pipe line 52, and the switching valve 2, and the actuator 4 is shortened, the position of the weight load W is lowered, and the throttle 1
3b has a structure that prevents the actuator 4 from running out of control by regulating the amount of pressure oil returned and flowing out within the load side chamber 4a.

Further, the switching valve 3 is similarly switched by the operating lever 7, and the pressure oil discharged from the variable displacement pump 1 is supplied to the actuator 5 from the hydraulic conduit 54a or 54b for forward and reverse driving.

(Problem to be solved by the invention) In the conventional hydraulic circuit, the flow rate of pressure oil return from the load side chamber is regulated by a throttle in order to prevent runaway of the actuator under weighted load. There are problems such as a large pressure loss occurs, and the potential energy stored in the load-side chamber as hydraulic pressure is completely released to the tank, resulting in a large waste of energy.

(Means for solving the problem) The present invention is a hydraulic circuit with an energy regeneration mechanism for construction machinery in order to deal with the above-mentioned problems. , in a hydraulic circuit for a construction machine in which a hydraulic pipe line of an actuator to which a load is applied is connected via a switching valve that is switched and controlled by the control mechanism, the hydraulic pipe line connected to a load side chamber of the actuator is connected to the An energy regeneration valve is provided, which is switched and controlled by the control mechanism when pressure oil is discharged from the load side chamber, and diverts the discharged pressure oil from the load side chamber to join the discharge pipe and the hydraulic pipe line of the non-load side chamber of the actuator. By switching the pressure reduction signal valve provided between the variable displacement pump and the control mechanism at the same time as switching the energy regeneration valve, it is possible to regenerate the potential energy stored in the actuator that is subject to a weighted load, thereby reducing the power burden. The above-mentioned problems are solved by reducing energy consumption and increasing driving efficiency as well as energy saving.

(Function) When pressurized oil is discharged from the load side chamber of the actuator subjected to a load, the energy regeneration valve is automatically switched by the control mechanism, and the energy regeneration valve connects the pressure oil in the load side chamber to the discharge pipe of the variable displacement pump. It merges into the hydraulic pipe in the non-load side chamber of the actuator and is regenerated as driving force, and the pressure reduction signal valve reduces the capacity and discharge flow rate of the variable displacement pump, reducing the power burden and increasing driving efficiency by regenerating potential energy. operation is now smoother.

(Embodiment) An embodiment of the present invention is shown in FIG. Hydraulic lines 52, 5 of the actuator 4 are loaded with weight via the switching valve 2 which is switched and controlled by the mechanism A.
2a and 53 are connected, and the hydraulic lines 54a and 54b of the actuator 5 are connected via the switching valve 3 which is switched and controlled by the control mechanism A, forming a hydraulic circuit for a construction machine. Hydraulic pipes 52, 52a connected to 4a,
An energy regeneration valve 18 which is switched and controlled by the control mechanism A when the pressure oil in the load side chamber 4a is discharged to divert the discharged pressure oil from the load side chamber 4a and merge it into the discharge pipe 50 and the hydraulic pipe 53 of the non-load side chamber 4b of the actuator 4.
A hydraulic circuit with an energy regeneration mechanism is provided in which a pressure reduction signal valve 19 is provided in pilot pipe lines 55, 57, and 70 between the variable displacement pump 1 and the control mechanism A.

The operation of the hydraulic circuit with an energy regeneration mechanism will be explained as well as the configuration thereof.

When the operating lever 6 of the control mechanism A is operated to the right in the figure, the secondary pressure of the pressure reducing valve 6b increases, the pilot pressure of the pilot line 56 increases, the switching valve 2 is switched to the function 2c, and the variable displacement pump 1 is switched to the function 2c. The discharge pressure oil is transferred from the discharge pipe line 50 to the switching valve 3,
2. Hydraulic oil is supplied to the load side chamber 4a of the actuator 4 via the hydraulic line 52, the energy regeneration valve 18 and the hydraulic line 52a, and the hydraulic oil in the non-load side chamber 4b passes through the hydraulic line 53 and the switching valve 2 to the tank _T1. The actuator 4 is elongated against the gravity F of the weighted load (weight load) W, and at this time, the pilot pressure in the pilot line 56 is controlled by the shuttle valve 8, the pilot line 57, and the pressure reduction signal. Valve 1
It is transmitted to the discharge amount adjusting device 11 of the variable displacement pump 1 through the function 19a of the pressure reducing valve 6b and the shuttle valve 10, and when the amount of operation of the operating lever 6 increases and reaches the upper limit position determined by the stopper S, the secondary pressure of the pressure reducing valve 6b increases. The upper limit pressure is determined by the relief valve 16, and this upper limit pressure becomes the pilot pressure and acts on the discharge amount adjusting device 11, which is actuated against the spring 11d to pump the pump discharge amount when the operating lever is in the neutral position. The actuator 4 is stopped from the minimum position 11a to the position 11c where the discharge amount is maximum, and the actuator 4 can lift the weighted load W at high speed against the gravity F. Potential energy corresponding to the stroke of the rod 4c is accumulated.

When lowering the position of the weighted load W according to the necessity of work, operating the operating lever 6 to the left in the figure increases the secondary pressure of the pressure reducing valve 6a, increases the pilot pressure of the pilot pipe 55, and switches. The valve 2 is switched to the function 2a, and the discharge pressure oil of the variable displacement pump 1 is transferred to the non-load side chamber 4b via the hydraulic pipe line 53.
is supplied to At this time, the pressure reduction signal valve 19 is switched to the function 19b by the increased pilot pressure in the pilot line 55, and
The pilot pressure of the pilot line 55 selected as high pressure by the shuttle valve 8 is transmitted to the pilot line 57, and the pilot pressure of the pilot line 57 is controlled by the two-stage throttle 19c, 1 in the function 19b.
The pressure is reduced at step 9d, and the pilot line 70 is supplied with the intermediate pressure between the pilot pressure in the pilot line 57, that is, the pilot line 55, and the tank T pressure.

Therefore, even if the operating lever 6 is operated to the left to the upper limit position determined by the stopper S and the secondary pressure of the pressure reducing valve 6a reaches the upper limit value, the pilot pressure in the pilot line 70 will only reach the reduced intermediate pressure. not reached. Furthermore, since the other operating lever 7 is in the neutral position and the pilot pressures in the pilot lines 58, 59 and 60 are low and equal to the pressure in the tank T, the pilot lines 70 and 70 are
The intermediate pressure acts on the pump discharge amount adjusting device 11, and the adjusting device operates against the spring 11d, but does not reach the pump discharge amount maximum position 11c.
It stops at an intermediate discharge amount position 11b that corresponds to the above-mentioned intermediate pressure. Further, if the intermediate pressure is sufficiently low, the pump remains stopped at the minimum discharge amount position 11a.

Therefore, only an intermediate discharge amount or a minimum discharge amount is supplied from the variable displacement pump 1 to the non-load side chamber 4b, and the energy regeneration valve 18 is simultaneously activated by the pilot pressure of the pilot line 55.
The flow is switched from 8a to 18c via 18b, and therefore, part of the pressure oil that has stored potential energy in the load side chamber 4a is transferred from the throttle 18f to the tank _T1.
Most of it passes through the check valve 18d and goes directly from the hydraulic line 53 to the non-load side chamber 4b, and some of it flows from the check valve 18e through the hydraulic line 61 to the discharge line 50, the switching valve 2, and then to the hydraulic line. 53 to the non-load side chamber 4c, which joins the discharge pressure oil of the variable displacement pump 1.

Therefore, the lowering speed of the rod 4c of the actuator 4 does not decrease, and the discharge amount of the variable displacement pump 1 is reduced, so the load on the prime mover 12 that supplies power to the pump can be reduced, and energy saving can be achieved. Become.

In addition, if you try to operate another actuator 5 at the same time as the actuator 4 is lowered and fully operate the operating lever 7 either to the left or right to the upper limit position determined by the stopper S, the secondary pressure of the pressure reducing valve 7a or 7b will be lowered to the upper limit. The switching valve 3 becomes the function 3a or 3c. In addition, the shuttle valve 9
A pressure reducing valve 7a or 7b is connected to the pilot line 60.
Since the upper limit value of the secondary pressure is generated, the pressure becomes higher than the intermediate pressure that was generated in the pilot line 70, and the pilot pressure in the pilot line 60 is applied to the discharge amount adjusting device 11 from the shuttle valve 10. , the pump discharge amount adjusting device 11 operates against the spring 11d and reaches the maximum discharge amount position 11c.

Therefore, if only the actuator 4 is lowered, a sufficient operating speed can be expected even if the amount of oil discharged from the variable displacement pump 1 is small due to the backup of the return oil storing potential energy in the load side chamber 4a. In this system, the shortage of discharge oil of the variable displacement pump 1 when other actuators 5 are operated simultaneously is automatically resolved, and the oil in the load side chamber 4a is further supplied to the actuator 4 through the hydraulic pipe 61. are fed together through the discharge pipe 50 and the switching valve 3,
The operating speed of both actuators is ensured above a certain value, which is revolutionary in terms of effective energy use.

Note that when lowering the actuator 4,
When the operating lever 6 is slightly operated, the switching valve 2 does not completely become the function 2a, and the bypass passage 2d
is not completely closed, the energy regeneration valve 18 is likewise in the intermediate position 18b and the load side chamber 4
It is possible that the pressure oil in a flows from the hydraulic pipe line 61 to the discharge pipe line 50 and is discarded from the bypass 2d to the tank, but this can be prevented in practice by keeping the opening of the throttle 18g sufficiently small at the intermediate position 18b. do not have. In the figure, 14 is a hydraulic pressure supply pump for pilot pressure, and 15 is an accumulator.

(Effects of the invention) Since the present invention has the above-described configuration, when the pressure oil is discharged from the load side chamber of the actuator that is subjected to a weight load, the energy regeneration valve is automatically switched by the control mechanism, and the energy regeneration valve is automatically switched. The energy regeneration valve merges the pressure oil in the load side chamber into the variable displacement pump's discharge line and the hydraulic line in the non-load side chamber of the actuator and regenerates it as driving force, so the potential energy accumulated in the load side chamber of the actuator is regenerated. (Pressure oil) regeneration significantly reduces the power burden, and the pressure reduction signal valve reduces and saves the discharge flow rate, or capacity, of the variable displacement pump, saving energy and increasing drive efficiency, significantly improving operating performance.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing one embodiment of the present invention;
The figure is a circuit diagram of a conventional example, and FIG. 3 is a side view of the power shovel. A... Control mechanism, 1... Variable displacement pump, 2...
...Switching valve, 4...Actuator, 4a...Load side chamber, 4b...Non-load side chamber, 18...Energy regeneration valve, 19...Pressure reduction signal valve, 50...Discharge piping, 52, 52a, 53...Hydraulic pressure Piping.

Claims (1)

[Scope of utility model registration request] A hydraulic circuit for a construction machine in which a hydraulic pipe of an actuator to which a load is applied via a switching valve controlled by the control mechanism is connected to a discharge pipe of a variable displacement pump whose capacity is controlled by a control mechanism,
When the pressure oil in the load side chamber is discharged, the control mechanism switches and controls the discharge pressure oil in the load side chamber to be diverted to the hydraulic pipe line connected to the load side chamber of the actuator so that the discharge line and the actuator are not under load. A construction machine characterized in that an energy regeneration valve is provided to join the hydraulic pipe line in a side chamber, and a pressure reduction signal valve provided between the variable displacement pump and the control mechanism is switched at the same time as the energy regeneration valve is switched. Hydraulic circuit with energy regeneration mechanism.