Hydraulic riding trowels with automatic load sensing
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
E01C-019/22
출원번호
US-0661007
(2010-03-09)
등록번호
US-8360680
(2013-01-29)
발명자
/ 주소
Allen, J. Dewayne
Guinn, Timmy D.
Waldon, Edward A.
Sugg, Scott R.
출원인 / 주소
Allen Engineering Corporation
인용정보
피인용 횟수 :
4인용 특허 :
79
초록▼
High performance, multiple rotor, hydraulically driven riding trowels for finishing concrete have unloader valve circuitry for controlling hydraulic pressure. Each trowel has a rigid frame with two or more downwardly-projecting, bladed rotor assemblies that finish concrete. The rotor assemblies are
High performance, multiple rotor, hydraulically driven riding trowels for finishing concrete have unloader valve circuitry for controlling hydraulic pressure. Each trowel has a rigid frame with two or more downwardly-projecting, bladed rotor assemblies that finish concrete. The rotor assemblies are tilted manually or hydraulically to effectuate steering and control. Blade pitch is controlled manually or hydraulically. The unloader valve system monitors drive pump pressure with a shuttle valve to derive an unloader pilot signal. A sequence valve responds to the unloader pilot signal to control a pressure valve that bypasses the normal foot control valve in an overpressure situation. The pressure control head signal normally applied to the hydraulic drive motor control heads is modified with a feedback signal to automatically control the associated pump swash plates. A gearbox may be disposed between the drive motors and rotors. Piston type and gear and vane type motors may power the rotors.
대표청구항▼
1. A motorized, hydraulic riding trowel for finishing concrete, said riding trowel comprising: rotor means pivotally suspended from said riding trowel, said rotor means comprising a plurality of radially spaced apart blades for frictionally contacting the concrete;manually operated control levers fo
1. A motorized, hydraulic riding trowel for finishing concrete, said riding trowel comprising: rotor means pivotally suspended from said riding trowel, said rotor means comprising a plurality of radially spaced apart blades for frictionally contacting the concrete;manually operated control levers for tilting the rotor means to effectuate trowel steering, maneuvering, and propulsion;hydraulic drive motor means for rotating said rotor means;primary hydraulic pump means for supplying hydraulic flow pressure;pump control head means for controlling said primary hydraulic pump means for supplying flow and pressure to said hydraulic drive motors;a pump control head (PCH) control line for controlling said pump control head means;user operated foot-pedal valve means for controlling said primary hydraulic pump means by pressuring said pump control head (PCH) line; and,unloader valve means for dynamically responding to varying friction and load fluctuations encountered in trowel use and generating an unloader pressure signal (UPS), the unloader valve means comprising: unloader pressure signal means for sensing output pressure from said primary hydraulic pump means and deriving said unloader pressure signal (UPS) when an optimum set point pressure condition occurs; and,pressure control head means for normally conducting fluid from said foot-pedal valve means to said pump control head (PCH) control line and for interrupting normal fluid flow from said foot-pedal valve means to said pump control head (PCH) line in response to said unloader pressure signal (UPS). 2. The trowel as defined in claim 1 wherein said unloader valve means comprises a shuttle valve for sensing pressure output by said hydraulic pump means, and a sequence valve responsive to said shuttle valve for generating said unloader pressure signal (UPS) when an optimum set point pressure condition occurs. 3. The trowel as defined in claim 1 wherein said pump control head (PCH) control valve means comprises diverter valve means for normally establishing an unobstructed fluid flow path from said foot pedal valve means to said pump control head (PCH) line and for providing an increased resistance path from said foot pedal valve means to said pump control head (PCH) line in response to said unloader pressure signal (UPS). 4. The trowel as defined in claim 3 wherein said pump control head (PCH) control valve means comprises pressure reduction valve means for establishing said increased resistance path from said foot pedal valve means to said pump control head (PCH) line in response to said diverter valve means. 5. The trowel as defined in claim 4 further comprising blade pitch control means for varying rotor blade pitch. 6. The trowel as defined in claim 5 wherein said blade pitch control mean comprises hydraulic actuation means, and said trowel comprises auxiliary pump means for supplying pressure and flow to said blade pitch hydraulic actuation means and said foot pedal valve means. 7. The trowel as defined in claim 5 wherein: said unloader valve means comprises a shuttle valve for sensing pressure applied to said hydraulic motor means, and a sequence valve responsive to said shuttle valve for generating said unloader pressure signal (UPS) when an optimum set point pressure condition occurs; and,said pump control head (PCH) control valve means comprises diverter valve means for normally establishing an unobstructed fluid flow path from said foot pedal valve means to said pump control head (PCH) line and for providing an increased resistance path from said foot pedal valve means to said pump control head (PCH) line in response to said unloader pressure signal (UPS). 8. The trowel as defined in claim 7 wherein said pump control head (PCH) control valve means comprises pressure reduction valve means for establishing said increased resistance path from said foot pedal valve means to said pump control head (PCH) line in response to said diverter valve means. 9. A motorized, hydraulic riding trowel for finishing concrete, said riding trowel comprising: a pair of rotors pivotally suspended from said riding trowel, said rotors comprising a plurality of radially spaced apart blades for frictionally contacting the concrete;steering means for tilting the rotors to effectuate trowel steering and maneuvering;means accessible to a trowel operator for selectively activating said steering means, whereby the operator of the trowel can steer and control the riding trowel hydraulically;hydraulic drive motors on each rotor for rotating said rotors;gearbox means for speed reduction disposed between said drive motors and said rotorsprimary hydraulic pump means for supplying hydraulic pressure to said rotors;a pump control head associated with said primary hydraulic pump means for controlling said drive motors;a pump control head (PCH) control line connected to said pump control heads;foot-pedal valve means for controlling said primary hydraulic pumps by pressuring said pump control head (PCH) line; and,unloader valve means for dynamically responding to varying friction and load fluctuations encountered in trowel use, the unloader valve means comprising: unloader pressure signal (UPS) circuit means for sensing output pressure on each primary hydraulic pump and deriving a unloader pressure signal (UPS) when an overpressure condition occurs; and, Pressure Control Head means for normally conducting fluid from said foot-pedal valve means to said pump control head (PCH) control line and for interrupting normal fluid flow from said foot-pedal valve means to said pump control head (PCH) line in response to said unloader pressure signal (UPS). 10. The trowel as defined in claim 9 wherein said unloader pressure signal (UPS) circuit means comprises a shuttle valve for sensing pressure output by both rotor motor pumps, and a sequencer valve for outputting said unloader pressure signal (UPS) in response to said shuttle valve when an optimum set point pressure condition occurs. 11. The trowel as defined in claim 10 wherein said pump control head (PCH) control valve means comprises diverter valve means for normally establishing an unobstructed fluid flow path from said foot pedal valve means to said pump control head (PCH) line and for providing an increased resistance path from said foot pedal valve means to said PCH line in response to said unloader pressure signal (UPS). 12. The trowel as defined in claim 11 wherein said pressure control head pump control head (PCH) control valve means comprises pressure reduction valve means for establishing said increased resistance path from said foot pedal valve means to said pump control head (PCH) line in response to said diverter valve means. 13. The trowel as defined in claim 12 wherein said primary hydraulic pump means is selected from the group consisting of: Separate hydraulic pumps for each rotor; andA single hydraulic pump and a splitter to divert hydraulic flow to each rotor. 14. A motorized, hydraulic riding trowel for finishing concrete, said riding trowel comprising: a pair of rotors pivotally suspended from said riding trowel, said rotors comprising a plurality of radially spaced apart blades for frictionally contacting the concrete;manually operated control levers for tilting the rotors to effectuate trowel steering and maneuvering;means accessible to a trowel operator for selectively activating said steering means, whereby the operator of the trowel can steer and control the riding trowel hydraulically;hydraulic drive motors on each rotor for rotating said rotors, the hydraulic drive motors selected from the group consisting of piston type hydraulic motors and gear and vane type motors;a primary hydraulic pump for each rotor drive motor for supplying hydraulic pressure to said drive motors;a pump control head on each primary hydraulic pump for controlling said drive motors;a pump control head (PCH) control line connected to said pump control heads;foot-pedal valve means for controlling said primary hydraulic pumps by pressuring said pump control head (PCH) line; and,unloader valve means for dynamically responding to varying friction and load fluctuations encountered in trowel use, the unloader valve means comprising: unloader pressure signal (UPS) circuit means for sensing output pressure on each primary hydraulic pump and deriving a unloader pressure signal (UPS) when an overpressure condition occurs; and, Pressure Control Head means for normally conducting fluid from said foot-pedal valve means to said pump control head (PCH) control line and for interrupting normal fluid flow from said foot-pedal valve means to said pump control head (PCH) line in response to said unloader pressure signal (UPS). 15. The trowel as defined in claims 14 further comprising gearbox means for speed reduction disposed between said drive motors and said rotors. 16. The trowel as defined in claim 14 wherein said unloader pressure signal (UPS) circuit means comprises a shuttle valve for sensing pressure output by both rotor motor pumps, and a sequencer valve for outputting said unloader pressure signal (UPS) in response to said shuttle valve when an optimum set point pressure condition occurs. 17. The trowel as defined in claim 16 wherein said pump control head (PCH) control valve means comprises diverter valve means for normally establishing an unobstructed fluid flow path from said foot pedal valve means to said pump control head (PCH) line and for providing an increased resistance path from said foot pedal valve means to said pump control head (PCH) line in response to said unloader pressure signal (UPS). 18. The trowel as defined in claim 17 wherein said pressure control head pump control head (PCH) control valve means comprises pressure reduction valve means for establishing said increased resistance path from said foot pedal valve means to said pump control head (PCH) line in response to said diverter valve means. 19. The trowel as defined in claims 18 further comprising gearbox means for speed reduction disposed between said drive motors and said rotors.
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