GB2156439A

GB2156439A - Hydro-electrical systems

Info

Publication number: GB2156439A
Application number: GB08505665A
Authority: GB
Inventors: Robert R Cooper; William C Dean
Original assignee: FMC Corp
Current assignee: FMC Corp
Priority date: 1984-03-05
Filing date: 1985-03-05
Publication date: 1985-10-09
Also published as: FR2560569B1; GB8505665D0; FR2560569A1; ES540953A0; ES8608433A1; GB2156439B

Abstract

A hydraulic and electrical system for battery powered aircraft belt loaders which precludes actuation of the electric traction drive motors (112) when the brake (94) is applied or set, or without the operator seat (122) being occupied; which precludes actuation of the belt conveyor motor (36) if the brake is not set; which controls conveyor run time and requires that the conveyor be reset to neutral before being actuated after its timed run has been completed; which actuates the hydraulic pump (10) to permit power steering when the operator seat is occupied; and which requires that the directional control lever for traction drive to reset to neutral after demounting the seat before the electric traction drive motors can be energised. <IMAGE>

Description

SPECIFICATION Hydraulic and electrical system for aircraft belt loader This invention relates generally to hydraulic and electrical systems for aircraft belt loaders and more particularly to such systems with interlocks to facilitate efficient and safe operation.

The present invention provides a hydraulic and electrical system for battery powered aircraft belt loaders which precludes actuation of the electric traction drive motors when the brake is applied or set, or without the operator sear being occupied, which precludes actuation of the belt conveyor if the brake is not set, which controls conveyor run time and requires that the conveyor be reset to neutral before being actuated after its timed run has been completed, which actuates the hydraulic pump to permit power steering when the operator seat is occupied, and which requires that the directional control lever for traction drive be reset to neutral after demounting the seat before the electric traction drive motors can be energized.Other advantages and desirable attributes of the present invention will become apparent from a perusal of the following description and the accompanying drawing, wherein the sole figure is a hydraulic and electric schematic of a system according to the present invention.

Referring to the drawing, the hydraulic system includes a pump 10 which draws hydraulic fluid from a reservoir 12 and discharges fluid under pressure into supply conduit 14 which connects with a directional control valve 16. A pair of conduits 18 and 20 connect the head and rod ends of hydraulic cylinder 22 with the valve 16. Shifting the valve 16 to the right will direct fluid pressure to conduit 20 causing the cylinder 22 to contract; the conduit 18 being connected with the reservoir 12.

Shifting the valve 16 to the left will connect conduit 18 with pump pressure causing the cylinder 22 to extend; the conduit 20 being connected with reservoir 12. A conduit 24 interconnects the flowthrough parts of valve 16 and a valve 26, which valve is connected with the head and rod ends of hydraulic cylinder 28 by conduits 30 and 32. Shifting the valve 26 left and right will cause this cylinder 28 to respectively extend and contract by connecting the conduit 30 with pump pressure for extension and conduit 28 with pump pressure for retraction; the other conduit in each case being connected with the reservoir 12. The cylinders 22 and 28 are connected to front and rear links mounting a belt conveyor on the chassis of an aircraft belt loader and extend to raise and contract to lower the associated end of the conveyor.

A third valve 34 is connected with a reversible hydraulic motor 36 by conduits 38 and 40. A conduit 42 interconnects the flow-through ports of valve 26 and 34. Shifting the valve 34 left and right from its center neutral position will cause the motor 36 to be selectively driven in each direction. A detent mechanism 44 holds the valve 34 in each of its shifted positions. The motor 36 is connected to drive the belt conveyor on the aircraft belt loader.

A conduit 46 connects the flow-through port of valve 34 with a hydrostatic steering circuit, indicated generally at 48, which is conventional and may be the steering system sold by Eaton Fluid Power Products as their Char-Lynn open center system, non-load reaction circuit. The output of the steering circuit is controlled by a steering wheel 50 and is directed to a steering cylinder 52 mechanically connected to control the angular orientation of the steerable ground-engaging wheels on the aircraft belt loader.

An electric motor 54 is mechanically connected to drive the hydraulic pump 10 and is powered by a 72 volt battery 56. The actual connection of the battery 56 to the motor 54 is controlled by a plurality of interlocks, as is the electric traction drive motors, to be described hereinafter. The battery 56 is connected by conductor 58 to a voltage reducer 60 which provides 12 volts for certain controll relays and switches. A branch conductor 59 connects the battery 56 to the master or key switch 118 which is connected by conductor 61 to the contacts of relay 80. The relay 80 is energized by voltage monitor device 82 which holds the contacts of relay 80 closed until the voltage of battery 56 drops below a predetermined level. The opening of the contacts on relay 80 at the predetermined low voltage level disables the conveyor motor control in a manner to be described hereinafter.Conductor 70 connects the contacts of relay 80 with the contact of relay 96 and with the contacts of relay 68 through branch conductor 74 and to the contacts of relay 104 through the branch conductor 72. The output from the reducer 60 is connected by conductor 62 to a normally open switch 66 associated with the valve 26. Switch 66 is closed when valve 26 is shifted in either direction from its center neutral position which energizes relay 68 closing its contacts. Control relay 106 is thereby energized through conductor 76 closing its contacts which connects conductor 77 branching from conductor 58 to conductor 78. The motor 54 will therefore be energized and the hydraulic pump 10 is driven thereby.

Switch 83 on valve 16 is closed when this valve is shifted from its neutral position. Conductors 84 and 86 connect switch 83 in parallel with switch 66 so that relay 68 is energized whenever either of the valves 16 and 26 are shifted. The contacts of relay 68 are closed to thereby energize control relay 106 to close its contacts and complete the electric circuit between the battery 56 and the motor 54.

A similar switch 88 is associated with valve 34 and is connected in series through conductor 90 with a switch 92, which switch is closed when the parking brake, indicated by handle 94, is applied.

When both switches 92 and 88 are closed, the relay 96 is energized, through conductor 98, closing the contacts of this relay. A zeneer diode 100 drops the voltage to 48 volts which is fed to a conventional solid state time delay 102. The output of time delay 102 is connected with relay 104, which has normally closed contacts. When the time delay 104 was timed out, the relay 104 is energized opening its contacts and breaking the circuit to the control relay 106. Closing the contacts of relay 106 will provide electric power to the motor 54 as described previously. Thus, regardless of the shifted position of valve 34, which is retained in its shifted position by detent 44, the motor 54 will be deenergized when time delay 104 has timed out.Since relay 96 must be deenergized to restart the time delay )02, the valve 34 must be physically returned to neutral position to open the contacts of relay 96 before the conveyor motor 36 can be operated after time delay 102 has timed out. This minimizes the possibility of the belt conveyor being driven in an unintended direction. Also, the contracts of relay 96 are in series with the contacts of relay 80, which relay is controlled by the voltage moniter device 82. Thus relay 96 cannot be energized if the voltage in battery 56 has fallen below a predetermine level. Any attempt to run the conveyor hydraulic motor 36 by actuation of valve 34 under low voltage conditions would alert an operator that the loader must be returned to a charging station for recharging of battery 56.

The two drive wheels, one of which is shown at 110, of the loader are driven by separate electric motors, one of which is shown at 112, connected in parallel. Traction drive in the forward direction is controlled by relay 114 and in the reverse direction by relay 116. The voltage applied is varied by controller EV1. The speed control of the motors is in reality more complex than illustrated here, but reference may be made to published manuals of General Electric Company regarding that company's electric vehicle controller referred to as EV-1 for more detail information.One of the control signals to EV-1 is generated by a series connection of the key switch 118, the set switch 129 which is closed when seat 122 is occupied, a switch 124 which is closed when the parking brake is released, and a switch 126 which is closed when the foot accelerator 127 is initially depressed. Power cannot be directed to the electric motor 112 if the parking brake is applied, which preserves battery power, or if the seat is not occupied. A double pole, single throw switch 128 is associated with the directional control lever 130 and provides control signals to EV-1 through conductors 132 and 134. Similarly control signals have provided to EV-1 upon closing the key switch 118 through conductor 136 and upon closing the seat switch 120 through conductor 138. The controller EV-1 will not actuate relays 114 and 116 if a signals arrives, or is present from either of the conductors 132 and 134 before a signal arrives either from the key switch 118 through conductor 136 or from the seat switch 120 through conductor 138. This arrangement requires the lever 130 be returned after the seat has been demounted and reoccupied before traction drive can be initiated.

In order to provide pump pressure for steering in any circumstance, a conductor 140 is connected from the seat switch 120 to energize control relay 106 and thereby provide electric power to motor 54. The hydraulic pump 10 will, therefore, be driven whenever the seat 122 is occupied. Thus, hydraulic power is available for actuation of steering cylinder 52 in response to rotation of the steering wheel 50.

Claims

1. An electro-hydraulic system for an aircraft belt loader having a belt conveyor with a front lift cylinder for controlling the vertical elevation of the front thereof comprising: a battery; a hydraulic pump; an electric motor, mechanically connected to drive said pump; a front lift valve, having a neutral position, connected between said pump and said front lift cylinder; and means responsive to shifting said lift valve from its neutral position to connect said motor and said battery;

2. The invention according to claim 1, wherein said motor includes a rear lift cylinder for controlling the vertical elevation of the rear of said conveyor comprising; a rear lift valve having a neutral position connected between said pump and said rear lift cylinder; and second means responsive to shifting said rear valve from its neutral position to connect said motor and battery.

3. The invention according to claim 2 wherein said loader includes a hydraulic motor for driving said belt conveyor comprising: a drive valve having a neutral position connected between said pump and hydraulic motors; and third means responsive to shifting said drive valve from its neutral position to connect electric motor and battery.

4. The invention according to claim 3, and further comprising: a voltage monitor connected to disable said third means when the voltage of said battery drops below a predetermined level.

5. The invention according to claim 3, and further comprising: detent means for holding said drive valve when shifted from said neutral position; time delay means interposed in said third means to interrupt the connection between said battery and electric motor when a selectable predetermined time has elapsed and requiring that said drive valve means be returned to neutral to restart the said predetermined time.

6. In an aircraft belt loader having a battery capable of connection with traction motors, a belt conveyor adjustable by front and rear lift cylinders, a seat, and a parking brake; an electro-hydraulic system comprising: a hydraulic pump; an electric motor for driving said pump; a motor control relay which, when energized, connects said electric motor to said battery; a pair of lift valves for controlling hydraulic flow to said lift cylinders; a pair of switches, one associated with each lift valve, connected in parallel to a lift relay and closed upon shifting the associated lift valve from neutral to energize the lift relay; and means connecting said lift relay to said control relay to produce hydraulic fluid pressure in response to shifting of either of said lift valves.

7. The invention according to claim 6, and further comprising: a hydraulic motor for driving said belt conveyor; a drive valve, with detent means to hold the same when shifted from its neutral position, interposed between said hydraulic motor and said pump.

a drive switch associated with said drive valve and closed when said drive valve is shifted from its neutral position; a drive relay energized when said drive switch is closed; a timer relay having normally closed contacts connected to energize said control relay; and a time delay means which energize the said time relay after elapse of a selectable predetermined time to open the timer relay contacts and deenergize said control relay.

8. The invention according to claim 7, wherein said time delay means must be deenergized by returning sad drive valve to neutral before a new predetermined time interval can begin.

9. The invention according to claim 8, further comprising: a first parking brake switch associated in series with said drive valve switch whereby said conveyor can be driven only when said parking brake is applied.

10. The invention according to claim 9 and further comprising: a second parking brake switch interposed between said battery and said traction motors to permit electrical connection therebetween only when the parking brake is released.

11. The invention according to claim 10 and further comprising: a seat switch interposed between said battery and said traction motors to permit connection therebetween only when said seat is occupied.

12. The invention according to claim 11, wherein said loader includes a power steering system, and further comprising: a direct electrical connection from said seat switch to said control relay to energize said electric motor to drive said pump whenever said seat is occupied.

13. An electro-hydraulic system for an aircraft belt loader as claimed in Claim 1 or an aircraft belt loader incorporating an electro-hydraulic system as claimed in Claim 6 and substantially as described with reference to or as shown by the Drawings.