ELECTRO-HYDRAULIC DRIVE SYSTEM FOR A WORK MACHINE

• US 20130180247A1
• Filed: 07/13/2011
• Published: 07/18/2013
• Est. Priority Date: 08/18/2010
• Status: Active Grant

• Current Assignee: Kawasaki Jukogyo Kabushiki Kaisha (Kawasaki Heavy Industries Limited)
• Original Assignee: Kawasaki Jukogyo Kabushiki Kaisha (Kawasaki Heavy Industries Limited)
• Inventors: Yamada, Masahiro, Yamamoto, Ryo, Imamura, Yukito
• Granted Patent: US 9,109,586 B2
• Time in Patent Office: Days
• US Class Current: 60/706
• CPC Class Codes: B60K 6/20 the prime-movers consisting of electric motors and internal combustion engines, e.g. HEVs
• CPC Class Codes: B60W 2300/17 Construction vehicles, e.g. graders, excavators
• CPC Class Codes: E02F 9/123 Drives or control devices specially adapted therefor E02F9/125 and E02F9/128 take precedence
• CPC Class Codes: E02F 9/2075 of the hybrid type for vehicles in general B60W20/00
• CPC Class Codes: E02F 9/2095 Control of electric, electro-mechanical or mechanical equipment not otherwise provided for, e.g. ventilators, electro-driven fans control of hydraulic driven equipment E02F9/22
• CPC Class Codes: E02F 9/2217 with energy recovery arrangements, e.g. using accumulators, flywheels
• CPC Class Codes: E02F 9/2296 Systems with a variable displacement pump
• CPC Class Codes: F01C 13/04 for driving pumps or compressors
• CPC Class Codes: F03C 1/0636 having rotary cylinder block
• CPC Class Codes: F03C 1/0678 Control
• CPC Class Codes: F03C 1/26 adapted for special use or combined with apparatus driven thereby
• CPC Class Codes: F04B 17/03 driven by electric motors
• CPC Class Codes: F04B 49/002 Hydraulic systems to change the pump delivery
• 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 2211/20546 variable capacity
• CPC Class Codes: F15B 2211/50527 using cross-pressure relief valves
• CPC Class Codes: F15B 2211/633 representing a state of the prime mover, e.g. torque or rotational speed
• CPC Class Codes: F15B 2211/6336 representing a state of the output member, e.g. position, speed or acceleration
• CPC Class Codes: F15B 2211/88 : Control measures for saving energy
• CPC Class Codes: F16H 61/4148 : Open loop circuits
• CPC Class Codes: H02K 7/00 : Arrangements for handling mechanical energy structurally associated with dynamo-electric machines, e.g. structural association with mechanical driving motors or auxiliary dynamo-electric machines
• CPC Class Codes: H02K 7/1807 : Rotary generators H02K7/006 takes precedence
• CPC Class Codes: H02P 3/14 : by regenerative braking

Abstract

An electro-hydraulic drive system for a work machine which drives an upper rotary body by controlling a flow rate of a hydraulic fluid by a control valve, includes an electro-hydraulic pump including a hydraulic pump driven by an engine, and a first electric motor, and an electro-hydraulic motor including a hydraulic motor rotated by the hydraulic oil supplied from the electro-hydraulic pump, and a second electric motor, and a controller which determines an operating state of the first electric motor and an operating state of the second electric motor based on a load of the electro-hydraulic pump and a load of the electro-hydraulic motor, and is able to perform an efficient operation by using a hydraulic pressure (fluid pressure) and electric power.

Claims

1. An electro-hydraulic drive system for a work machine which drives a structure body by controlling a flow rate of a hydraulic fluid by a control valve, comprising:

a supply device which includes a hydraulic pump driven by a driving power source, and a first electric motor, and supplies the hydraulic fluid;

a drive device which includes a hydraulic motor rotated by the hydraulic fluid supplied from the supply device, and a second electric motor, and drives the structure body; and

a controller which decides an operating state of the first electric motor and an operating state of the second electric motor, based on a load of the supply device and a load of the drive device.

2. The electro-hydraulic drive system for the work machine according to claim 1,

wherein the first electric motor has a generator function of converting driving power transmitted from the driving power source into electric energy, and a drive unit function of assisting driving of the hydraulic pump by utilizing the electric energy;

and

wherein the controller performs control to operate the first electric motor as a generator or a drive unit based on a state of charge in a charging unit which stores electric power generated by the generator function and an operating state of the first electric motor.

3. The electro-hydraulic drive system for the work machine according to claim 1,

wherein the second electric motor has a generator function of converting inertia energy into the electric energy during deceleration of the hydraulic motor and a drive unit function of assisting driving of the hydraulic motor by utilizing the electric energy;

and

wherein the controller performs control to operate the second electric motor as a generator or a drive unit based on a state of charge in the charging unit which stores the electric power generated by the generator function and an operating state of the second electric motor.

4. The electro-hydraulic drive system for the work machine according to claim 1,

wherein the drive device is configured such that the hydraulic motor and the second electric motor are integral with each other;

wherein the second electric motor includes a rotor connected to a rotary shaft of the hydraulic motor and a stator disposed on an outer periphery of the rotor; and

wherein the rotor is disposed to surround an outer periphery of a casing of the hydraulic motor such that the rotor is spaced apart a predetermined gap from the outer periphery of the casing; and

wherein a bearing for supporting the rotor on the casing and a seal member for sealing the gap between the rotor and the casing are disposed between the rotor and the casing.

5. The electro-hydraulic drive system for the work machine according to claim 1,

wherein the supply device is configured such that the hydraulic pump and the first electric motor are integral with each other.

6. The electro-hydraulic drive system for the work machine according to claim 2,

wherein the second electric motor has a generator function of converting inertia energy into the electric energy during deceleration of the hydraulic motor and a drive unit function of assisting driving of the hydraulic motor by utilizing the electric energy;

and

wherein the controller performs control to operate the second electric motor as a generator or a drive unit based on a state of charge in the charging unit which stores the electric power generated by the generator function and an operating state of the second electric motor.

7. The electro-hydraulic drive system for the work machine according to claim 2,

wherein the drive device is configured such that the hydraulic motor and the second electric motor are integral with each other;

wherein the second electric motor includes a rotor connected to a rotary shaft of the hydraulic motor and a stator disposed on an outer periphery of the rotor; and

wherein the rotor is disposed to surround an outer periphery of a casing of the hydraulic motor such that the rotor is spaced apart a predetermined gap from the outer periphery of the casing; and

wherein a bearing for supporting the rotor on the casing and a seal member for sealing the gap between the rotor and the casing are disposed between the rotor and the casing.

8. The electro-hydraulic drive system for the work machine according to claim 3,

wherein the drive device is configured such that the hydraulic motor and the second electric motor are integral with each other;

wherein the second electric motor includes a rotor connected to a rotary shaft of the hydraulic motor and a stator disposed on an outer periphery of the rotor; and

wherein the rotor is disposed to surround an outer periphery of a casing of the hydraulic motor such that the rotor is spaced apart a predetermined gap from the outer periphery of the casing; and

wherein a bearing for supporting the rotor on the casing and a seal member for sealing the gap between the rotor and the casing are disposed between the rotor and the casing.

9. The electro-hydraulic drive system for the work machine according to claim 6,

wherein the drive device is configured such that the hydraulic motor and the second electric motor are integral with each other;

wherein the second electric motor includes a rotor connected to a rotary shaft of the hydraulic motor and a stator disposed on an outer periphery of the rotor; and

wherein the rotor is disposed to surround an outer periphery of a casing of the hydraulic motor such that the rotor is spaced apart a predetermined gap from the outer periphery of the casing; and

wherein a bearing for supporting the rotor on the casing and a seal member for sealing the gap between the rotor and the casing are disposed between the rotor and the casing.

10. The electro-hydraulic drive system for the work machine according to claim 2,

wherein the supply device is configured such that the hydraulic pump and the first electric motor are integral with each other.

11. The electro-hydraulic drive system for the work machine according to claim 3,

wherein the supply device is configured such that the hydraulic pump and the first electric motor are integral with each other.

12. The electro-hydraulic drive system for the work machine according to claim 4,

wherein the supply device is configured such that the hydraulic pump and the first electric motor are integral with each other.

13. The electro-hydraulic drive system for the work machine according to claim 6,

wherein the supply device is configured such that the hydraulic pump and the first electric motor are integral with each other.

14. The electro-hydraulic drive system for the work machine according to claim 7,

wherein the supply device is configured such that the hydraulic pump and the first electric motor are integral with each other.

15. The electro-hydraulic drive system for the work machine according to claim 8,

wherein the supply device is configured such that the hydraulic pump and the first electric motor are integral with each other.

16. The electro-hydraulic drive system for the work machine according to claim 9,

wherein the supply device is configured such that the hydraulic pump and the first electric motor are integral with each other.