Swing drive device and work machine

• US 7,565,801 B2
• Filed: 04/10/2006
• Issued: 07/28/2009
• Est. Priority Date: 06/06/2005
• Status: Expired due to Fees

• Current Assignee: Caterpillar Sarl (Caterpillar Incorporated)
• Original Assignee: Caterpillar Japan Limited (Caterpillar International Investments Companyöperatie UA)
• Inventors: Tozawa, Shoji, Binnaka, Madoka, Furuta, Hideto
• Primary Examiner(s): Leslie; Michael
• Application Number:
  US11/573,866
• Publication Number:
  US 20080314038A1
• Time in Patent Office: 1,205 Days
• Field of Search: 604/14, 604/17, 604/24, 604/84, 604/86, 604/88
• US Class Current: 60/414
• CPC Class Codes: E02F 9/2075 of the hybrid type for vehicles in general B60W20/00
• CPC Class Codes: E02F 9/2217 with energy recovery arrangements, e.g. using accumulators, flywheels
• CPC Class Codes: E02F 9/2242 including an electronic controller
• CPC Class Codes: E02F 9/2292 Systems with two or more pumps
• CPC Class Codes: E02F 9/2296 Systems with a variable displacement pump
• CPC Class Codes: F15B 11/17 using two or more pumps
• CPC Class Codes: F15B 21/14 Energy-recuperation means
• CPC Class Codes: F15B 2211/20515 Electric motor
• CPC Class Codes: F15B 2211/20523 Internal combustion engine
• CPC Class Codes: F15B 2211/20538 constant capacity
• CPC Class Codes: F15B 2211/20546 variable capacity
• CPC Class Codes: F15B 2211/20576 with multiple pumps
• CPC Class Codes: F15B 2211/3111 the pump port being closed in the centre position, e.g. so-called closed centre
• CPC Class Codes: F15B 2211/327 electrically or electronically
• CPC Class Codes: F15B 2211/63 Electronic controllers
• CPC Class Codes: F15B 2211/7053 Double-acting output members
• CPC Class Codes: F15B 2211/7058 Rotary output members
• CPC Class Codes: F15B 2211/88 Control measures for saving energy

Abstract

A swing control circuit is provided separately from a hydraulic actuator control circuit. The swing control circuit includes a swing pump motor connected to closed circuits of a swing motor through a solenoid valve that serves as a directional control valve. A swing motor generator is connected to the swing pump motor. The swing motor generator is connected to an electric power storage device of a hybrid type drive system. An exterior-connecting passage for feeding hydraulic fluid to hydraulic actuators of a lower structure and a work equipment is drawn from a pipeline between the swing pump motor and the solenoid valve. A connecting passage solenoid valve is disposed in the exterior-connecting passage. The invention enables hydraulic energy generated in the swing system to be directly fed to the outside of the swing system.

Claims

1. A work machine comprising:

a lower structure provided with a travel motor adapted to function by receiving hydraulic fluid;

an upper structure that is rotatable on the lower structure by a swing motor functioning by receiving hydraulic fluid;

work equipment mounted on the upper structure;

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 driven by either one of or both the engine and the motor generator;

a hydraulic actuator control circuit for controlling hydraulic fluid fed from the main pump of the hybrid type drive system to hydraulic actuators of the lower structure as well as hydraulic actuators of the work equipment;

a swing drive device rotating the upper structure by controlling hydraulic fluid fed to the swing motor, comprising;

a swing pump motor connected to the swing motor through a closed circuit and adapted to function as a pump for feeding hydraulic fluid to the swing motor and also function as a hydraulic motor driven by hydraulic fluid discharged from the swing motor;

a directional control valve having a neutral position and a directional control position, the neutral position being a position at which the directional control valve interrupts a passage between the swing pump motor and the swing motor;

a swing motor generator functioning as a generator by being driven by the swing pump motor when the swing pump motor is functioning as a hydraulic motor during braking operation of rotation of the load, the swing motor generator also functioning as an electric motor by receiving electric power so as to drive the swing pump motor as a pump;

the electric power storage device also storing electric power fed from the swing motor generator when the swing motor generator is functioning as a generator, electric power storage device also serving to feed electric power to the swing motor generator when the swing motor generator is functioning as an electric motor;

an exterior-connecting passage feeding hydraulic fluid from the closed circuit between the swing pump motor and the directional control valve to components outside a swing system;

a connecting passage solenoid valve disposed in the exterior-connecting passage and adapted to be moved between a position for enabling supply of fluid to components outside the swing system and a position for interrupting the flow of fluid; and

a hydraulic fluid replenishment device replenishing hydraulic fluid in the closed circuit between the swing pump motor and the directional control valve;

wherein the work equipment comprises 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;

wherein the hydraulic actuator control circuit serves to control hydraulic fluid fed from the main pumps of the hybrid type drive system to the travel motor of the lower structure as well as to the boom cylinder, the stick cylinder, and the bucket cylinder of the work equipment;

wherein the exterior-connecting passage is connected to a discharge passage of the main pump, which serves to feed hydraulic fluid to the boom cylinder, the stick cylinder, and the travel motor;

wherein the hydraulic actuator control circuit comprises;

a boom assist pump for assisting 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 passage through which return fluid discharged from the boom cylinder flows;

a boom motor generator 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 transmitting electric power from the boom motor generator to the boom assist pump when the boom motor generator is functioning as an electric motor and disengage the boom motor generator from the boom assist pump when the boom motor generator is functioning as a generator.

2. A swing drive device as claimed in claim 1, wherein:

a hydraulic fluid replenishment pump serves as the hydraulic fluid replenishment means.

3. A work machine claimed in claim 1, wherein the hydraulic actuator control circuit further includes:

a circuit-to-circuit communicating passage between stick and boom for providing fluid communication between a hydraulic fluid feeding passage for the stick cylinder and a head-side of the boom cylinder; and

a solenoid valve between stick and boom, the solenoid valve between stick and boom being 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 hydraulic fluid feeding passage for the stick cylinder to the head-side of the boom cylinder and a position for interrupting the flow of fluid.

4. A work machine claimed in claim 3, wherein:

a first main pump and a second main pump are provided and serve as the aforementioned main pump; and

the hydraulic actuator control circuit further includes;

a boom cylinder hydraulic fluid feeding passage for feeding hydraulic fluid from the first main pump 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 for feeding hydraulic fluid from the second main pump to the stick cylinder,

a boom assist pump that serves, together with the first main pump, to feed hydraulic fluid to the boom cylinder,

a solenoid valve between bucket and boom disposed in the boom cylinder hydraulic fluid feeding passage, at a location between a 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,

a solenoid valve between bucket and stick, the solenoid valve between bucket and stick being 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 for the stick cylinder and a position for interrupting the flow of fluid,

a pump-to-pump communicating passage for providing fluid communication between a discharge passage of the boom assist pump and the discharge passage of the first main pump, and

a solenoid valve between pumps that is disposed in the pump-to-pump communicating passage and adapted to be moved between a position for enabling flow in one direction from the discharge passage of the boom assist pump to the discharge passage of the first main pump and a position for interrupting the flow of fluid.

5. A work machine claimed in claim 1, wherein:

a first main pump and a second main pump are provided and serve as the aforementioned main pump; and

the hydraulic actuator control circuit further includes;

a boom cylinder hydraulic fluid feeding passage for feeding hydraulic fluid from the first main pump 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 for feeding hydraulic fluid from the second main pump to the stick cylinder,

wherein the boom assist pump serves, together with the first main pump, to feed hydraulic fluid to the boom cylinder,

a solenoid valve between bucket and boom disposed in the boom cylinder hydraulic fluid feeding passage, at a location between a 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,

a solenoid valve between bucket and stick, the solenoid valve between bucket and stick being 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 for the stick cylinder and a position for interrupting the flow of fluid,

a pump-to-pump communicating passage for providing fluid communication between a discharge passage of the boom assist pump and the discharge passage of the first main pump, and

a solenoid valve between pumps that is disposed in the pump-to-pump communicating passage and adapted to be moved between a position for enabling flow in one direction from the discharge passage of the boom assist pump to the discharge passage of the first main pump and a position for interrupting the flow of fluid.