Materials handling vehicle measuring electric current flow into/out of a hydraulic system motor
원문보기
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
B66F-009/22
B66F-009/00
B66F-017/00
B66F-009/07
B66F-009/08
B66F-009/24
B66F-009/20
출원번호
US-0333944
(2014-07-17)
등록번호
US-9296598
(2016-03-29)
발명자
/ 주소
Dammeyer, Karl L.
Holbrook, Eric D.
Ihle, Darrin R.
McClain, Marc A.
Waltz, Lucas B.
출원인 / 주소
Crown Equipment Corporation
대리인 / 주소
Stevens & Showalter, LLP
인용정보
피인용 횟수 :
0인용 특허 :
76
초록▼
A materials handling vehicle is provided comprising: a support structure including a fixed member; a movable assembly coupled to the support structure; a hydraulic system; and a control system. The support structure further comprises lift apparatus to effect movement of the movable assembly relative
A materials handling vehicle is provided comprising: a support structure including a fixed member; a movable assembly coupled to the support structure; a hydraulic system; and a control system. The support structure further comprises lift apparatus to effect movement of the movable assembly relative to the support structure fixed member. The lift apparatus includes at least one ram/cylinder assembly. The hydraulic system includes a motor, a pump coupled to the motor to supply a pressurized fluid to the at least one ram/cylinder assembly, and at least one electronically controlled valve associated with the at least one ram/cylinder assembly. The control structure may measure an electric current flow into and/or out of the hydraulic system motor and reduce an operating speed of the hydraulic system motor if the electric current flow into and/or out of the hydraulic system motor is greater than or equal to a predetermined threshold value.
대표청구항▼
1. A materials handling vehicle comprising: a support structure including a fixed member;a movable assembly coupled to said support structure;said support structure further comprising lift apparatus to effect movement of said movable assembly relative to said support structure fixed member, said lif
1. A materials handling vehicle comprising: a support structure including a fixed member;a movable assembly coupled to said support structure;said support structure further comprising lift apparatus to effect movement of said movable assembly relative to said support structure fixed member, said lift apparatus including at least one ram/cylinder assembly;a hydraulic system including a motor and a pump coupled to said motor to supply a pressurized fluid to said at least one ram/cylinder assembly; andcontrol structure to measure an electric current flow into or out of said hydraulic system motor and to control an operating speed of said hydraulic system motor using a comparison involving the electric current flow into or out of said hydraulic system motor and a predetermined threshold value, said control structure reducing the operating speed of said hydraulic system motor if the electric current flow into or out of said hydraulic system motor is greater than or equal to the predetermined threshold value. 2. The materials handling vehicle as set forth in claim 1, wherein said fixed member comprises a fixed mast weldment coupled to a power unit. 3. The materials handling vehicle as set forth in claim 1, wherein said lift apparatus comprises at least one movable mast weldment and said movable assembly comprises a fork carriage assembly which moves relative to said support structure fixed member. 4. The materials handling vehicle as set forth in claim 1, wherein said hydraulic system further comprises at least one electronically controlled valve associated with said at least one ram/cylinder assembly. 5. The materials handling vehicle as set forth in claim 4, wherein said control structure further estimates a speed of said movable assembly from a speed of said motor and controls the operation of said at least one valve using a comparison of the estimated movable assembly speed to a determined movable assembly speed, wherein said control structure determines the determined movable assembly speed based on a speed of said movable assembly relative to said support structure fixed member. 6. The materials handling vehicle as set out in claim 5, wherein said control structure is capable of energizing said at least one valve so as to open said at least one valve to permit said movable assembly to be lowered in a controlled manner to a desired position relative to said support structure fixed member. 7. The materials handling vehicle as set forth in claim 6, wherein said control structure de-energizes said at least one valve in response to an operator-generated command to cease further descent of said movable assembly relative to said support structure fixed member. 8. The materials handling vehicle as set forth in claim 7, wherein said at least one valve functions as a check valve when de-energized so as to block pressurized fluid from flowing out of said at least one ram/cylinder assembly, and allows pressurized fluid to flow into said at least one ram/cylinder assembly during a movable assembly lift operation. 9. The materials handling vehicle as set forth in claim 5, wherein said support structure further comprises a power unit;said support structure fixed member comprises a fixed first mast weldment coupled to said power unit;said lift apparatus comprises: a second mast weldment movable relative to said first mast weldment; anda third mast weldment movable relative to said first and second mast weldments;said at least one ram/cylinder assembly comprises: at least one first ram/cylinder assembly coupled between said first and second mast weldments for effecting movement of said second and third mast weldments relative to said first mast weldment; anda second ram/cylinder assembly coupled between said third mast weldment and said movable assembly so as to effect movement of said movable assembly relative to said third mast weldment; andsaid at least one electronically controlled valve comprises: at least one first solenoid-operated, normally closed, proportional valve associated with said at least one first ram/cylinder assembly; anda second solenoid-operated, normally closed, proportional valve associated with said second ram/cylinder assembly. 10. The materials handling vehicle as set forth in claim 9, wherein said control structure comprises: encoder apparatus associated with said movable assembly for generating encoder pulses as said movable assembly moves relative to said first mast weldment; anda controller coupled to said encoder apparatus and said valves for receiving said encoder pulses generated by said encoder apparatus, and determining the determined movable assembly speed based on the encoder pulses. 11. The materials handling vehicle as set out in claim 10, wherein said control structure controls the operation of said at least one first valve and said second valve by comparing the determined movable assembly speed with at least one of: a first threshold speed based on the estimated movable assembly speed; andthe first threshold speed and a fixed, second threshold speed. 12. The materials handling vehicle as set out in claim 11, wherein said controller functions to de-energize said at least one first valve and said second valve causing them to move from their powered open state to their closed state in the event said movable assembly moves downwardly at the determined movable assembly speed in excess of one of the first and second threshold speeds. 13. The materials handling vehicle as set forth in claim 12, wherein said controller slowly closes said at least one first valve and said second valve in the event said movable assembly moves downwardly at a speed in excess of said first or said second threshold speed. 14. The materials handling vehicle as set forth in claim 13, wherein said controller causes said at least one first valve and said second valve to move from their powered open position to their closed position over a time period of from about 0.3 second to about 1.0 second. 15. The materials handling vehicle as set forth in claim 5, wherein said control structure estimates the movable assembly speed from the motor speed by: converting motor speed into a pump fluid flow rate, converting the pump fluid flow rate into a ram speed and converting the ram speed into the estimated movable assembly speed. 16. The materials handling vehicle as set forth in claim 4, wherein said at least one valve comprises a solenoid-operated, normally closed, proportional valve. 17. The materials handling vehicle as set forth in claim 4, wherein said at least one valve is positioned in a base of said at least one ram/cylinder assembly. 18. The materials handling vehicle as set forth in claim 1, wherein said hydraulic system motor receives power from a battery for driving said hydraulic system pump. 19. The materials handling vehicle as set forth in claim 1, wherein said control structure further estimates a speed of said movable assembly from a speed of said motor and calculates an updated pump volumetric efficiency using the estimated movable assembly speed and a determined movable assembly speed, wherein said control structure determines the determined movable assembly speed based on a speed of said movable assembly relative to said support structure fixed member. 20. The materials handling vehicle as set forth in claim 19, wherein said control structure determines the updated volumetric efficiency using the following equation: updated volumetric efficiency=(determined movable assembly speed*current volumetric efficiency)/estimated movable assembly speed. 21. The materials handling vehicle as set forth in claim 20, wherein the current volumetric efficiency is derived based on one or more of a speed of the materials handling vehicle, a direction of rotation of the pump, a pressure of the pressurized fluid, a temperature of the pressurized fluid, and a viscosity of the pressurized fluid.
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