| CPC E02F 9/2296 (2013.01) [E02F 9/123 (2013.01); E02F 9/2203 (2013.01); E02F 9/2225 (2013.01); E02F 9/2228 (2013.01); F15B 11/042 (2013.01); F15B 11/163 (2013.01); E02F 9/121 (2013.01); F15B 2211/20553 (2013.01); F15B 2211/30555 (2013.01); F15B 2211/3111 (2013.01); F15B 2211/351 (2013.01); F15B 2211/40507 (2013.01); F15B 2211/7053 (2013.01); F15B 2211/7058 (2013.01); F15B 2211/7135 (2013.01); F15B 2211/7142 (2013.01); F15B 2211/75 (2013.01); F15B 2211/781 (2013.01)] | 6 Claims |
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1. A working machine comprising:
a plurality of hydraulic actuators including a high-load hydraulic actuator and a low-load hydraulic actuator, a hydraulic pressure required for actuation of the low-load hydraulic actuator being lower than a hydraulic pressure required for actuation of the high-load hydraulic actuator;
a plurality of direction switching valves that are provided so as to correspond to the plurality of hydraulic actuators, respectively, and each of which switches a direction of hydraulic fluid for a corresponding one of the hydraulic actuators, the plurality of direction switching valves including a low-load direction switching valve that switches a direction of hydraulic fluid for the low-load hydraulic actuator; and
a plurality of dummy-load forming units that each forms a dummy load in the low-load direction switching valve to suppress a variation in an actuation speed of the low-load hydraulic actuator between a time when the high-load hydraulic actuator and the low-load hydraulic actuator are operated in combination and a time when the low-load hydraulic actuator is operated singly,
wherein the low-load direction switching valve includes a first flow passage through which a hydraulic fluid flows to a one-side port of the low-load hydraulic actuator, and a second flow passage through which a hydraulic fluid flows to an other-side port of the low-load hydraulic actuator,
a high-load direction switching valve that is one of the direction switching valves and switches a direction of hydraulic fluid for the high-load hydraulic actuator, includes a first fluid passage through which a hydraulic fluid flows to a one-side port of the high-load hydraulic actuator, and a second fluid passage which is different from the first fluid passage and through which a hydraulic fluid flows to an other-side-port of the high-load hydraulic actuator,
one of the plurality of dummy-load forming units includes a first throttle that is provided in the first flow passage and another one of the plurality of dummy-load forming units includes a second throttle that is provided in the second flow passage, and
the first fluid passage and the second fluid passage are not provided with a throttle.
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5. A working machine comprising:
a plurality of hydraulic actuators including a high-load hydraulic actuator and a low-load hydraulic actuator, a hydraulic pressure required for actuation of the low-load hydraulic actuator being lower than a hydraulic pressure required for actuation of the high-load hydraulic actuator;
a plurality of direction switching valves that are provided so as to correspond to the plurality of hydraulic actuators, respectively, and each of which switches a direction of hydraulic fluid for a corresponding one of the hydraulic actuators, the plurality of direction switching valves including a low-load direction switching valve that switches a direction of hydraulic fluid for the low-load hydraulic actuator;
a dummy-load forming unit that forms a dummy load in the low-load direction switching valve to suppress a variation in an actuation speed of the low-load hydraulic actuator between a time when the high-load hydraulic actuator and the low-load hydraulic actuator are operated in combination and a time when the low-load hydraulic actuator is operated singly;
a first control valve that controls the high-load hydraulic actuator and that includes a pressure compensation valve that sets a pressure difference between a pressure of a hydraulic fluid that is introduced thereinto and a pressure of a hydraulic fluid output therefrom to be constant; and
a second control valve that controls the low-load hydraulic actuator and that includes the low-load direction switching valve and a flow-rate prioritizing valve that prioritizes a flow rate of a hydraulic fluid output to the low-load hydraulic actuator via the low-load direction switching valve,
wherein the low-load direction switching valve has a flow passage through which a hydraulic fluid flows toward the low-load hydraulic actuator,
wherein the dummy-load forming unit includes a throttle that is provided in the flow passage,
wherein the flow-rate prioritizing valve includes
a spool that is movable between a first position in which the spool increases a flow rate of a hydraulic fluid output from the low-load direction switching valve and a second position in which the spool reduces the flow rate of the hydraulic fluid output from the low-load direction switching valve, and
a pressing member that presses the spool toward the first position,
wherein the low-load direction switching valve includes a first flow passage that is the flow passage through which a hydraulic fluid flows to one side of the low-load hydraulic actuator, and a second flow passage that is the flow passage through which a hydraulic fluid flows to the other side of the low-load hydraulic actuator, and
wherein the dummy-load forming unit includes a first throttle that is the throttle provided in the first flow passage and a second throttle that is the throttle provided in the second flow passage.
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