JP6476953B2 - Hydraulic circuit for construction machinery - Google Patents

Description

  The present invention relates to a hydraulic circuit of a construction machine including a fan motor circuit that cools an oil cooler by driving a fan with a hydraulic motor.

  In a construction machine such as an excavator, a hydraulic circuit having a fan motor circuit shown in Patent Document 1 (hereinafter referred to as “known technology 1”) has been proposed.

  In this known technique 1, on the premise that the radiator cooling fan is driven by a hydraulic fan motor, the fan rotation speed (fan motor rotation speed) is reduced according to the radiator temperature from the viewpoint of preventing waste of energy. It is configured to control in the direction of lowering on the side.

  On the other hand, in Patent Document 2, as a warming-up technology for heating and raising the operating oil for operating the hydraulic actuator, the bleed valve is caused to generate heat by returning the pump discharge oil to the tank through the bleed valve at a low temperature. A technique for performing a warming-up operation (hereinafter referred to as “known technique 2”) is disclosed.

JP 2003-97268 A JP-A-11-117914

  In the known technique 1, if the radiator is replaced with an oil cooler, it can be directly used as a cooling technique for hydraulic oil.

  It is also possible to reduce the original cooling performance by stopping the fan or reducing the number of rotations of the fan, and as a result, increase the operating oil temperature, that is, warm up at a low temperature.

  However, since the cooling of the hydraulic oil is stopped and only a natural temperature rise is waited, and the active warm-up action is not performed, the warm-up efficiency is low and the warm-up takes a long time.

  On the other hand, according to the second prior art, a sufficient warm-up effect is obtained, but the hydraulic oil cannot be cooled.

  In addition, since the oil discharged from the main pump, which is the hydraulic pressure source of the hydraulic actuator circuit, is warmed up by bleeding into the tank, the pressure of the main pump rises during the warming up, which hinders the operation of the hydraulic actuator. . That is, there is a negative effect that the machine cannot be moved during warm-up.

  In addition, it is conceivable that a circuit dedicated to warming up the hydraulic fluid using the known technology 2 is provided in parallel with the fan motor circuit, and a circuit configuration for cooling and heating that switches both circuits is considered, but the circuit configuration is complicated and enlarged. It is not a good idea because it increases costs.

  Therefore, the present invention can use the fan motor circuit for cooling the hydraulic oil as it is as the hydraulic oil warm-up circuit, and can obtain a high warm-up effect, and also interferes with the operation of the hydraulic actuator during the warm-up. This is to provide a hydraulic circuit for a construction machine that does not cause the harmful effect.

  As means for solving the above problems, in the present invention, a hydraulic actuator circuit that drives a working hydraulic actuator using a main pump as a hydraulic source, an oil cooler that cools hydraulic oil in the hydraulic actuator circuit, and a hydraulic motor A fan that is driven by a fan motor to cool the oil cooler, a fan motor circuit that drives the fan motor using a fan pump as a hydraulic source, and a hydraulic oil tank that is shared by the hydraulic actuator circuit and the fan motor circuit The fan motor circuit is provided with a warm-up valve that performs a warm-up operation that heats the hydraulic oil by heating when the hydraulic oil flows, and a switching valve that switches a circuit state, and the switching position of the switching valve As a cooling position for supplying hydraulic oil discharged from the fan pump to the fan motor , In which the hydraulic oil discharged from the fan pump provided with warm-up position is supplied only to the warm-up valve.

  According to this configuration, both cooling and warming-up of the hydraulic oil can be performed with a single fan motor circuit.

  In this case, since the warm-up valve is operated in the fan stop state, that is, in the state where the heat dissipation action by the fan rotation is stopped, the warm-up valve is operated. Loss is eliminated and warm-up efficiency can be increased.

  In addition, the hydraulic actuator circuit and the fan motor circuit are driven by separate pumps and warmed up by the bleed action of the fan motor circuit, so the discharge pressure of the main pump does not increase during the warm-up even if the discharge pressure of the fan pump increases. . That is, there is no risk of hindering the operation of the hydraulic actuator using the main pump as a hydraulic source.

In the present invention, as the switching position of the switching valve, further Ru an intermediate position to return directly to the hydraulic oil tank hydraulic oil discharged from the fan pump.

  According to this configuration, the cooling state by the fan rotation and the warming-up state by the warming-up valve operation are not alternatives, and the hydraulic oil is not supplied to the fan motor or the warming-up valve, and neither cooling nor warming up is performed. By adding an intermediate position, energy efficiency can be increased by avoiding frequent switching between the cooling state and the warm-up state.

In the present invention, the upper Symbol switching valve, thereby constituting an automatic switching valve is switched by the switching signal from the outside, provided with a control means for sending a switching signal to the temperature of the hydraulic oil to detect and the switching valve, the control The means is described above, assuming that the detected hydraulic oil temperature is To, the warming-up setting value as a temperature at which the hydraulic oil should be warmed up is T1, and the cooling setting value as the temperature at which the hydraulic oil is to be cooled is T2. the switching valve, in the warm-up position when the the to ≦ T1, <in the intermediate position when the to ≦ T2, to> T1 you configured to set each of the cooling position when the T2.

  By so doing, cooling / warming / non-cooling / non-warming can be automatically and accurately switched according to the hydraulic oil temperature.

Further, a variable displacement pump is used as the fan pump, and the control means has a warm-up pump capacity q1 that is a capacity of the fan pump in a state where the switching valve is set at the warm-up position, The cooling pump capacity, which is the capacity of the fan pump determined by the target fan speed when the switching valve is set at the cooling position, is q2,
q1> q2
To set is not the desired.

  Thus, by increasing the pump capacity during warm-up than during cooling, first, the pump flow rate (warm-up valve passage flow rate) is increased to increase warm-up efficiency, and second, the engine pump load is increased. The engine can be warmed up efficiently by increasing it.

In this case, the control means sets q3 as the capacity of the fan pump in a state where the switching valve is set at the intermediate position,
q3 ≦ q2
To set is not the desired.

  In this way, the fan motor is not driven at the intermediate position of the switching valve, and a large flow rate is not required. Therefore, by reducing the pump discharge flow rate with the pump capacity being minimized, the pump load is reduced and energy is saved.

In the present invention, it is not to desirable to configure to drive the main pump and the fan pump by a common engine.

  In this way, when the hydraulic oil is warmed up, the fan pump becomes an engine load so that the engine can be warmed up simultaneously.

Further, in the fan motor circuit, provided a relief valve for setting the upper limit value of the circuit pressure, the relief valve has to wishing is configured to double as the warm-up valve.

  As described above, the relief valve that sets the upper limit value of the circuit pressure for circuit / device protection can also be used as the warm-up valve, which is advantageous in terms of simplification of the circuit configuration and cost.

  According to the present invention, the fan motor circuit for cooling the hydraulic oil can be used as the hydraulic oil warm-up circuit as it is, and a high warm-up effect can be obtained, and the operation of the hydraulic actuator is hindered during the warm-up. There is no fear.

1 is a hydraulic circuit diagram according to an embodiment of the present invention. It is a flowchart for demonstrating the effect | action of embodiment.

  An embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the hydraulic circuit according to the embodiment includes a hydraulic actuator circuit A that drives a hydraulic actuator 2 (one cylinder is illustrated in the figure) 2 by discharge oil from a main pump 1, and a fan pump 3, a fan motor circuit B that drives a fan motor (hydraulic motor) 4 by the oil discharged from 3 and a hydraulic oil tank (hereinafter simply referred to as “tank”) 5 that is shared by both the hydraulic actuator and fan motor circuits A and B. It has.

  In FIG. 1, reference numeral 6 denotes an engine as a common drive source for both the main and fan pumps 1, 3, reference numeral 7 denotes a control valve for controlling actuator operation constituting the hydraulic actuator circuit A, and reference numeral 8 is driven to rotate by a fan motor 4. The cooling fan 9 is an oil cooler provided in the return circuit of the hydraulic actuator circuit A. The rotation of the fan 8 cools the oil cooler 9, that is, the hydraulic oil passing through the oil cooler 9, and returns to the tank 5.

  The fan motor circuit B is provided with a relief valve 10 also serving as a warm-up valve for setting an upper limit value of the circuit pressure, and a switching valve 12 for switching the circuit state in the main pipeline 11 connecting the main pump 1 and the fan motor 4. Is provided.

  This switching valve 12 has cooling, intermediate and warming-up positions a, b, c in order from the left side of the figure, and each position a, b, c is received by a switching signal (electrical signal) from the controller 13 constituting the control means. It is configured as an electromagnetic automatic switching valve that switches between the two.

  The switching valve 12 may be configured as a hydraulic pilot switching valve, and an electric signal from the controller 13 may be converted into a hydraulic signal by the hydraulic pilot valve and input to the switching valve 12.

  The oil discharged from the fan pump 3 flows to the fan motor 4 through the main pipeline 11 at the cooling position A of the switching valve 12. That is, the fan 8 is rotationally driven by the fan motor 4 to cool the hydraulic oil.

  On the other hand, at the intermediate position B of the switching valve 12, the pump discharge oil returns directly to the tank 5 via the bypass line 14 that does not pass through the fan motor 4. Therefore, the fan motor 4 does not rotate, and neither cooling action nor warm-up action is performed.

  On the other hand, at the warm-up position C of the switching valve 12, the pump discharge oil is blocked for both the fan motor 4 and the bypass line 14 and flows only to the relief valve 10. Therefore, the hydraulic oil is heated by the relief operation and returns to the tank 5. That is, the warming-up action of the hydraulic oil is performed.

  The fan pump 3 is configured as a variable capacity pump whose capacity (pump tilt) is changed by the regulator 15, and the pump capacity, that is, the pump discharge flow rate is variable according to the capacity command signal input from the controller 13 to the regulator 15. Be controlled.

  On the other hand, a hydraulic oil temperature sensor 16 for detecting the temperature of the hydraulic oil and a pump rotational speed sensor 17 for detecting the rotational speed of the fan pump 3 are provided as detection means, and the operation detected by both sensors 16 and 17 is provided. The oil temperature and pump speed signals are sent to the controller 13.

  That is, the controller 13 and the sensors 16 and 17 constitute a control means for switching the switching valve 12.

  The controller 13 switches the operation including cooling of the hydraulic oil and warming up according to the detected hydraulic oil temperature, and the pump capacity of the pump 3 according to the switching of the operation and the rotational speed of the fan pump 3. To change. This point will be described in detail with reference to the flowchart of FIG.

  The controller 13 has a warm-up set value T1 as a temperature at which the hydraulic oil temperature is relatively low and should start warming-up of the hydraulic oil, and cooling of the hydraulic oil is started at a relatively high temperature. The cooling set value T2 as the power temperature is stored, and the detected hydraulic oil temperature To is compared with these set values T1 and T2.

  That is, after the control is started, it is determined whether or not To <T1 in step S1, and if NO (To ≧ T1), it is determined that there is no need for warm-up, and the process proceeds to step S2.

  In step S2, it is determined whether To <T2 or not. If NO (To> T2), it is determined that cooling is necessary. In step S3, the switching valve 12 is set to the cooling position A, and in step 4, the fan pump 3 Is set to the cooling pump capacity q2.

  The cooling pump capacity q2 is obtained from the target rotational speed Nf of the fan 8, the pump capacity qf required for one rotation of the fan, and the rotational speed Np of the fan pump 3 by the following equation.

q2 = qf × Nf / Np
In this way, the fan 8 rotates at a rotation speed necessary and sufficient for cooling, and the cooling action of the hydraulic oil is performed.

  On the other hand, if YES in Step S1 (To ≦ T1), it is determined that the hydraulic oil temperature is low and needs to be warmed up, so that the process proceeds to Step S5 and the switching valve 12 is set to the warming-up position C.

  In this warm-up position C, the oil discharged from the fan pump 3 does not flow into the fan motor 4 or the bypass line 14 as described above, so that the relief valve 10 is opened and the entire amount of oil discharged from the pump passes through the relief valve 10. Return to tank 5. That is, the warming-up action of heating the hydraulic oil to raise the temperature is performed.

  In step S6, the pump capacity q of the fan pump 3 is set to a warm-up pump capacity q1 larger than the cooling pump capacity q2.

  As a result, the pump discharge flow rate increases, so that the relief flow rate also increases and the warm-up efficiency increases.

  Further, when the pump load of the engine 6 increases, the amount of heat generated by the engine 6 increases and the warm-up efficiency of the engine 6 also increases.

  On the other hand, if YES in step S2 (To ≦ T2), that is, if T1 <To ≦ T2, the hydraulic oil temperature is in an intermediate region where the temperature is neither high nor low, and cooling and warming up are not necessary. To set the switching valve 12 to the intermediate position b.

  At this intermediate position b, the oil discharged from the fan pump 3 returns directly to the tank 5 through only the bypass line 14 without passing through the fan motor 4 or the relief valve 10. Accordingly, the fan 8 does not rotate, the relief operation is not performed, and neither the cooling operation nor the warming-up operation is performed.

  In step S8, the capacity q of the fan pump 3 is set to an intermediate pump capacity q3 smaller than the cooling pump capacity q2.

  In this way, the fan motor 4 is not driven and a large flow rate is not required in the intermediate temperature range where neither the cooling action nor the heating action is performed. Therefore, the pump load is reduced by minimizing the pump capacity to save energy. It becomes.

  According to this hydraulic circuit, the following effects can be obtained.

  (I) A single fan motor circuit B can both cool and warm up the hydraulic oil.

  (II) In order to warm up by operating the relief valve 10 as a warm-up valve in a state where the fan is stopped, that is, in a state where the heat radiation action due to the rotation of the fan is stopped, the warm-up valve is operated while the fan 8 is rotated. Compared to the case, it is possible to increase the warm-up efficiency by eliminating heat loss.

  (III) Since the hydraulic actuator circuit A and the fan motor circuit B are driven by separate pumps 1 and 3 and warmed up by the bleed action (relief action) of the fan motor circuit B, the discharge pressure of the fan pump 3 during warm-up Even if it rises, the discharge pressure of the main pump 1 does not rise. That is, there is no possibility of hindering the operation of the hydraulic actuator 2 using the main pump 1 as a hydraulic source.

  (IV) The switching position of the switching valve 12 is not one of the cooling state by the fan rotation and the warming-up state by the relief operation, and the hydraulic oil is not supplied to the fan motor 4 and the relief valve 10 and the cooling is not performed. Since an intermediate position B that does not warm up is added, energy efficiency can be increased by avoiding frequent switching between the cooling state and the warming up state.

  (V) The switching valve 12 is configured as an automatic switching valve that is switched by a switching signal from the controller 13, and is set to the warm-up position C when To ≦ T1, to the intermediate position B when T1 <To ≦ T2, and To> Since the cooling position A is set at T2, the cooling / warming / non-cooling / non-warming can be automatically and accurately switched according to the hydraulic oil temperature.

(VI) A variable capacity pump is used as the fan pump 3, and the relationship between the pump capacity q1 during warm-up and the pump capacity during cooling q2 is
q1> q2
Therefore, first, the pump discharge flow rate (relief flow rate) can be increased to increase the warm-up efficiency, and second, the pump load of the engine 6 can be increased to warm up the engine 6 as well.

(VII) The pump capacity q3 in a state where the switching valve 12 is set to the intermediate position b and is not cooled or warmed up,
q3 ≦ q2
Since the pump discharge flow rate is reduced by setting to, the pump load is reduced and energy is saved.

  (VIII) Since the main pump 1 and the fan pump 3 are driven by the common engine 6, when the hydraulic oil is warmed up, the fan pump 3 becomes an engine load so that the engine 6 can be warmed up simultaneously. .

  (IX) Since the relief valve 10 that sets the upper limit value of the circuit pressure of the fan motor circuit B is also used as a warm-up valve, it is advantageous in terms of simplification of the circuit configuration and cost.

Other embodiments
(1) In the above embodiment, the relief valve 10 of the fan motor circuit B is also used as a warm-up valve. However, a warm-up valve such as a dedicated variable throttle may be provided.

  (2) Although it is desirable to use a variable displacement pump for the fan pump 3 as in the above embodiment and change the pump displacement q according to the switching state of the cooling / warming / intermediate of the switching valve 12, the pump displacement q may be constant regardless of the switching state of the switching valve 12.

  (3) As the switching position of the switching valve 12, it is desirable to provide an intermediate position B that is neither cooled nor warmed up as in the above embodiment, but the switching valve 12 is switched between only two states of cooling and warming up. You may comprise as a valve.

  (4) In the above embodiment, the fan pump 3 is driven by the engine 6 common to the main pump 1. However, the fan pump 3 is driven by a drive source (for example, an electric motor) different from the engine 6. It may be taken.

A Hydraulic actuator circuit B Fan motor circuit 1 Main pump 2 Hydraulic actuator 3 Fan pump 4 Fan motor 5 Hydraulic oil tank 6 Engine 8 Fan 9 Oil cooler 10 Relief valve also serving as a warm-up valve 11 Main pipeline 12 Switching valve 13 Controller 14 Bypass Line 15 Regulator 16 Hydraulic oil temperature sensor 17 Pump speed sensor T1 Warm-up set value T2 Cooling set value To Hydraulic oil temperature q1 Warm-up pump capacity q2 Cooling pump capacity q3 Intermediate pump capacity

Claims (5)

A hydraulic actuator circuit that drives a working hydraulic actuator using a main pump as a hydraulic source, an oil cooler that cools hydraulic oil in the hydraulic actuator circuit, and a fan motor that is a hydraulic motor drives and cools the oil cooler. A fan, a fan motor circuit that drives the fan motor using a fan pump as a hydraulic source, and a hydraulic oil tank shared by the hydraulic actuator circuit and the fan motor circuit. A warm-up valve that generates heat by flowing and heats the hydraulic oil is provided, and a switching valve that switches the circuit state is provided. The hydraulic oil discharged from the fan pump is used as a switching position of the switching valve. The cooling position supplied to the fan motor and the hydraulic oil discharged from the fan pump And only supplying warm-up position Kiben, an intermediate position to return directly to the hydraulic oil tank hydraulic oil discharged from the fan pump, the switching valve, an automatic switching valve is switched by the switching signal from the outside And a control means for detecting the temperature of the hydraulic oil and sending a switching signal to the switching valve, and the control means should start the warming up of the hydraulic oil with the detected hydraulic oil temperature To Assuming that the warm-up set value as temperature is T1, the cooling set value as temperature at which hydraulic oil cooling is to be started is T2, the switching valve is in the warm-up position when To ≦ T1, and T1 <To ≦ T2 A hydraulic circuit for a construction machine, wherein the hydraulic circuit is set to the intermediate position at the time of the above, and the cooling position at the time of To> T2 . A variable displacement pump is used as the fan pump, and the control means has a warm-up pump capacity that is a capacity of the fan pump in a state where the switching valve is set at the warm-up position. The cooling pump capacity, which is the capacity of the fan pump determined by the target fan speed in the state set in the cooling position, is q2,
q1> q2
The hydraulic circuit for a construction machine according to claim 1, wherein The control means sets q3 as the capacity of the fan pump in a state where the switching valve is set at an intermediate position,
q3 ≦ q2
The hydraulic circuit for a construction machine according to claim 2, wherein The hydraulic circuit for a construction machine according to any one of claims 1 to 3 , wherein the main pump and the fan pump are driven by a common engine. To the fan motor circuit, provided a relief valve for setting the upper limit value of the circuit pressure, the relief valve to any one of claims 1 to 4, characterized by being configured to also as the warm-up valve Hydraulic circuit of the construction machine described.

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