A boom control circuit for controlling hydraulic fluid fed to a boom cylinder is provided separately and independently from a travel/stick/bucket control circuit, which serves to control hydraulic fluid fed to travel motors, a stick cylinder, and a bucket cylinder. The boom control circuit includes
A boom control circuit for controlling hydraulic fluid fed to a boom cylinder is provided separately and independently from a travel/stick/bucket control circuit, which serves to control hydraulic fluid fed to travel motors, a stick cylinder, and a bucket cylinder. The boom control circuit includes a boom pump, an energy recovery motor disposed in a return passage through which return fluid from the boom cylinder 8bmc passes, and a boom motor generator connected to the energy recovery motor. The aforementioned boom pump is connected through a clutch to the boom motor generator. The invention is capable of providing a work machine of which a boom control circuit is adapted to function independently so that the flow rate required by the boom control circuit can be easily ensured.
대표청구항▼
The invention claimed is: 1. A work machine comprising: a lower structure adapted to be driven by a travel motor; an upper structure that is rotatable on the lower structure by a swing motor generator, and a work equipment mounted on the upper structure and comprising a boom, a stick, and a bucket
The invention claimed is: 1. A work machine comprising: a lower structure adapted to be driven by a travel motor; an upper structure that is rotatable on the lower structure by a swing motor generator, and a work equipment mounted on the upper structure and comprising a boom, a stick, and a bucket that are sequentially connected and adapted to be pivoted by a boom cylinder, a stick cylinder and a bucket cylinder respectively; the work machine further including: a hybrid type drive system comprising: an engine, a motor generator adapted to be driven by the engine so as to function as a generator as well as receive electric power so as to function as an electric motor, an electric power storage device that serves to store electric power fed from the motor generator functioning as a generator, as well as feed electric power to the motor generator functioning as an electric motor, and a main pump adapted to be driven either one of or both the engine and the motor generator; a travel/stick/bucket control circuit that serves to control hydraulic fluid fed from the main pump of the hybrid type drive system to the travel motor, the stick cylinder, and the bucket cylinder; a boom control circuit that includes a boom pump, which is provided separately from the main pump of the hybrid type drive system, the boom control circuit serving to control hydraulic fluid fed from the boom pump to the boom cylinder; and a swing control circuit that serves to: feed electric power from the electric power storage device of the hybrid type drive system to the swing motor generator so that the swing motor generator functions as an electric motor, and recover to the electric power storage device electric power generated by the swing motor generator functioning as a generator during braking of rotating motion of the upper structure; wherein the boom control circuit further includes: an energy recovery motor provided in a return fluid passage through which return fluid discharged from the boom cylinder flows, a boom motor generator adapted to be driven by the energy recovery motor so as to function as a generator for feeding electric power to the electric power storage device of the hybrid type drive system as well as be driven by electric power fed from the electric power storage device so as to function as an electric motor, and a clutch that serves to transmit electric power from the boom motor generator functioning as an electric motor to the boom pump and disengage the boom motor generator functioning as a generator from the boom pump. 2. A work machine as claimed in claim 1, wherein: the return fluid passage includes: a return passage provided with the energy recovery motor, another return passage that branches off the upstream side of the energy recovery motor, and a flow rate ratio control valve for controlling a flow rate ratio of a flow rate in the first mentioned return passage and a flow rate in the other return passage. 3. A work machine as claimed in claim 1, wherein: the energy recovery motor is provided in the return fluid passage that extends from a head-side of the boom cylinder. 4. A work machine as claimed in claim 3, wherein: the return fluid passage includes: a return passage provided with the energy recovery motor, another return passage that branches off the upstream side of the energy recovery motor, and a flow rate ratio control valve for controlling a flow rate ratio of a flow rate in the first mentioned return passage and a flow rate in the other return passage. 5. A work machine as claimed in claim 3, wherein: the work machine includes a plurality of main pumps; and the hydraulic actuator control circuit further includes: a boom cylinder hydraulic fluid feeding passage for feeding hydraulic fluid from one of the main pumps to the boom cylinder, a bucket cylinder hydraulic fluid feeding passage that branches off the boom cylinder hydraulic fluid feeding passage and serves to feed hydraulic fluid to the bucket cylinder, a stick cylinder hydraulic fluid feeding passage that serves to feed hydraulic fluid from another main pump to the stick cylinder, a solenoid valve between bucket and boom that is disposed in the boom cylinder hydraulic fluid feeding passage, at a location between the branching point of the bucket cylinder hydraulic fluid feeding passage and a point at which a passage from the boom assist pump joins the boom cylinder hydraulic fluid feeding passage, the solenoid valve between bucket and boom being adapted to be moved between a position for enabling the hydraulic fluid that would otherwise be fed to the bucket cylinder to be fed to the boom cylinder in a one-way direction and a position for interrupting the flow of fluid, a circuit-to-circuit communicating passage between bucket and stick for providing fluid communication between the bucket cylinder hydraulic fluid feeding passage and the stick cylinder hydraulic fluid feeding passage, and a solenoid valve between bucket and stick that is disposed in the circuit-to-circuit communicating passage between bucket and stick and adapted to be moved between a position for enabling flow in one direction from the bucket cylinder hydraulic fluid feeding passage to the stick cylinder hydraulic fluid feeding passage and a position for interrupting the flow of fluid. 6. A work machine as claimed in claim 5, wherein: the work machine further includes: a circuit-to-circuit communicating passage between stick and boom for providing fluid communication between the stick cylinder hydraulic fluid feeding passage and the head-side of the boom cylinder, and a solenoid valve between stick and boom that is disposed in the circuit-to-circuit communicating passage between stick and boom and adapted to be moved between a position for enabling flow in one direction from the stick cylinder hydraulic fluid feeding passage to the head-side of the boom cylinder and a position for interrupting the flow of fluid. 7. A work machine as claimed in claim 2, wherein: the work machine includes a plurality of main pumps; and the hydraulic actuator control circuit further includes: a boom cylinder hydraulic fluid feeding passage for feeding hydraulic fluid from one of the main pumps to the boom cylinder, a bucket cylinder hydraulic fluid feeding passage that branches off the boom cylinder hydraulic fluid feeding passage and serves to feed hydraulic fluid to the bucket cylinder, a stick cylinder hydraulic fluid feeding passage that serves to feed hydraulic fluid from another main pump to the stick cylinder, a solenoid valve between bucket and boom that is disposed in the boom cylinder hydraulic fluid feeding passage, at a location between the branching point of the bucket cylinder hydraulic fluid feeding passage and a point at which a passage from the boom assist pump joins the boom cylinder hydraulic fluid feeding passage, the solenoid valve between bucket and boom being adapted to be moved between a position for enabling the hydraulic fluid that would otherwise be fed to the bucket cylinder to be fed to the boom cylinder in a one-way direction and a position for interrupting the flow of fluid, a circuit-to-circuit communicating passage between bucket and stick for providing fluid communication between the bucket cylinder hydraulic fluid feeding passage and the stick cylinder hydraulic fluid feeding passage, and a solenoid valve between bucket and stick that is disposed in the circuit-to-circuit communicating passage between bucket and stick and adapted to be moved between a position for enabling flow in one direction from the bucket cylinder hydraulic fluid feeding passage to the stick cylinder hydraulic fluid feeding passage and a position for interrupting the flow of fluid. 8. A work machine as claimed in claim 7, wherein: the work machine further includes: a circuit-to-circuit communicating passage between stick and boom for providing fluid communication between the stick cylinder hydraulic fluid feeding passage and the head-side of the boom cylinder, and a solenoid valve between stick and boom that is disposed in the circuit-to-circuit communicating passage between stick and boom and adapted to be moved between a position for enabling flow in one direction from the stick cylinder hydraulic fluid feeding passage to the head-side of the boom cylinder and a position for interrupting the flow of fluid. 9. A work machine comprising: a lower structure adapted to be driven by a travel motor; an upper structure that is rotatable on the lower structure by a swing motor generator, and a work equipment mounted on the upper structure and comprising a boom, a stick, and a bucket that are sequentially connected and adapted to be pivoted by a boom cylinder, a stick cylinder and a bucket cylinder respectively; the work machine further including: a hybrid type drive system comprising: an engine, a motor generator adapted to be driven by the engine so as to function as a generator as well as receive electric power so as to function as an electric motor, an electric power storage device that serves to store electric power fed from the motor generator functioning as a generator, as well as feed electric power to the motor generator functioning as an electric motor, and a main pump adapted to be driven either one of or both the engine and the motor generator; a hydraulic actuator control circuit that serves to control hydraulic fluid fed from the main pump of the hybrid type drive system to the travel motor, the boom cylinder, the stick cylinder, and the bucket cylinder; and a swing control circuit that serves to: feed electric power from the electric power storage device of the hybrid type drive system to the swing motor generator so that the swing motor generator functions as an electric motor, and recover to the electric power storage device electric power generated by the swing motor generator functioning as a generator during braking of rotating motion of the upper structure; wherein the hydraulic actuator control circuit further includes: a boom assist pump that serves to assist flow rate of hydraulic fluid fed from the main pump of the hybrid type drive system to the boom cylinder, an energy recovery motor provided in a return fluid passage through which return fluid discharged from the boom cylinder flows, and a boom motor generator adapted to be driven by the energy recovery motor so as to function as a generator for feeding electric power to the electric power storage device of the hybrid type drive system as well as be driven by electric power fed from the electric power storage device so as to function as an electric motor. 10. A work machine as claimed in claim 9, wherein: the energy recovery motor is provided in the return fluid passage that extends from a head-side of the boom cylinder. 11. A work machine as claimed in claim 10, wherein: the return fluid passage includes: a return passage provided with the energy recovery motor, another return passage that branches off the upstream side of the energy recovery motor, and a flow rate ratio control valve for controlling a flow rate ratio of a flow rate in the first mentioned return passage and a flow rate in the other return passage. 12. A work machine as claimed in claim 9, wherein: the return fluid passage includes: a return passage provided with the energy recovery motor, another return passage that branches off the upstream side of the energy recovery motor, and a flow rate ratio control valve for controlling a flow rate ratio of a flow rate in the first mentioned return passage and a flow rate in the other return passage. 13. A work machine as claimed in claim 9, wherein: the work machine includes a plurality of main pumps; and the hydraulic actuator control circuit further includes: a boom cylinder hydraulic fluid feeding passage for feeding hydraulic fluid from one of the main pumps to the boom cylinder, a bucket cylinder hydraulic fluid feeding passage that branches off the boom cylinder hydraulic fluid feeding passage and serves to feed hydraulic fluid to the bucket cylinder, a stick cylinder hydraulic fluid feeding passage that serves to feed hydraulic fluid from another main pump to the stick cylinder, a solenoid valve between bucket and boom that is disposed in the boom cylinder hydraulic fluid feeding passage, at a location between the branching point of the bucket cylinder hydraulic fluid feeding passage and a point at which a passage from the boom assist pump joins the boom cylinder hydraulic fluid feeding passage, the solenoid valve between bucket and boom being adapted to be moved between a position for enabling the hydraulic fluid that would otherwise be fed to the bucket cylinder to be fed to the boom cylinder in a one-way direction and a position for interrupting the flow of fluid, a circuit-to-circuit communicating passage between bucket and stick for providing fluid communication between the bucket cylinder hydraulic fluid feeding passage and the stick cylinder hydraulic fluid feeding passage, and a solenoid valve between bucket and stick that is disposed in the circuit-to-circuit communicating passage between bucket and stick and adapted to be moved between a position for enabling flow in one direction from the bucket cylinder hydraulic fluid feeding passage to the stick cylinder hydraulic fluid feeding passage and a position for interrupting the flow of fluid. 14. A work machine as claimed in claim 13, wherein: the work machine further includes: a circuit-to-circuit communicating passage between stick and boom for providing fluid communication between the stick cylinder hydraulic fluid feeding passage and the head-side of the boom cylinder, and a solenoid valve between stick and boom that is disposed in the circuit-to-circuit communicating passage between stick and boom and adapted to be moved between a position for enabling flow in one direction from the stick cylinder hydraulic fluid feeding passage to the head-side of the boom cylinder and a position for interrupting the flow of fluid. 15. A work machine as claimed in claim 9, wherein: the hydraulic actuator control circuit further includes a clutch that serves to transmit electric power from the boom motor generator functioning as an electric motor to the boom assist pump and disengage the boom motor generator functioning as a generator from the boom assist pump. 16. A work machine as claimed in claim 15, wherein: the work machine includes a plurality of main pumps; and the hydraulic actuator control circuit further includes: a boom cylinder hydraulic fluid feeding passage for feeding hydraulic fluid from one of the main pumps to the boom cylinder, a bucket cylinder hydraulic fluid feeding passage that branches off the boom cylinder hydraulic fluid feeding passage and serves to feed hydraulic fluid to the bucket cylinder, a stick cylinder hydraulic fluid feeding passage that serves to feed hydraulic fluid from another main pump to the stick cylinder, a solenoid valve between bucket and boom that is disposed in the boom cylinder hydraulic fluid feeding passage, at a location between the branching point of the bucket cylinder hydraulic fluid feeding passage and a point at which a passage from the boom assist pump joins the boom cylinder hydraulic fluid feeding passage, the solenoid valve between bucket and boom being adapted to be moved between a position for enabling the hydraulic fluid that would otherwise be fed to the bucket cylinder to be fed to the boom cylinder in a one-way direction and a position for interrupting the flow of fluid, a circuit-to-circuit communicating passage between bucket and stick for providing fluid communication between the bucket cylinder hydraulic fluid feeding passage and the stick cylinder hydraulic fluid feeding passage, and a solenoid valve between bucket and stick that is disposed in the circuit-to-circuit communicating passage between bucket and stick and adapted to be moved between a position for enabling flow in one direction from the bucket cylinder hydraulic fluid feeding passage to the stick cylinder hydraulic fluid feeding passage and a position for interrupting the flow of fluid. 17. A work machine as claimed in claim 16, wherein: the work machine further includes: a circuit-to-circuit communicating passage between stick and boom for providing fluid communication between the stick cylinder hydraulic fluid feeding passage and the head-side of the boom cylinder, and a solenoid valve between stick and boom that is disposed in the circuit-to-circuit communicating passage between stick and boom and adapted to be moved between a position for enabling flow in one direction from the stick cylinder hydraulic fluid feeding passage to the head-side of the boom cylinder and a position for interrupting the flow of fluid.
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이 특허에 인용된 특허 (5)
Moyna John P. ; Burnett Steven,GBX ; Prillinger Peter F. ; Young David A.,GBX, Hydraulic circuit for an ejector type dump mechanism for articulated trucks and the like.
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