Aerial Lift Vehicle

Abstract

An aerial lift vehicle having a carriage rotatably mounted on the vehicle, an electrically insulated boom support on said carriage and an aerial bucket pivotally carried at the upper end of said boom, a hydraulic system for moving the carriage and the boom, the hydraulic system including a number of electro-hydraulic proportional remote control valves, a set of electric controllers mounted on said boom for operating the valves, manually actuated levers for each of said electric controllers mounted in a fixed position in said bucket, an electrically insulated push-pull assembly in said boom connecting each of said levers to a corresponding electric controller and a second set of electric controllers connected to said valves at a point remote from said valves, the electrically insulated push-pull assemblies being connected to the mechanical controllers through a set of coaxially arranged rotatable linear motion actuators positioned at the pivot point of the connection of the aerial bucket to the boom.

Description

BACKGROUND OF THE INVENTION

There has been an increasing demand for mobile electric maintenance equipment which will reach high voltage power lines to allow linemen to work "live line, bare hand" on high voltage cables. A number of aerial lifts are presently being used which allow linemen to work safely near high voltage cables by insulating the linemen within the aerial bucket. This has been achieved by supporting the bucket on a nonconductive boom, generally made of a fiberglass reinforced plastic. It has been found that the control of the position of the bucket with respect to the high voltage cable can be more conveniently handled by the linemen in the bucket. In order to do this a full set of controls has to be placed within easy reach of the workmen in the bucket. Obviously, these controls must be made of nonconductive materials with very high dielectric strengths. Fiberglass rods have been used to control the operation of hydraulic control valves located at the base of the equipment. In this regard, it is generally known that mechanically actuated hydraulic systems have high flow characteristics at break out producing quick or sudden movements of the bucket. Control of the hydrauilc valves has made it difficult to accurately locate and maintain the bucket in a position convenient for the linemen to repair the cable. Some effort has been directed toward the use of radio signlas to control the position of the bucket, however, the complexity of these systems made them impractical from an economic standpoint.

SUMMARY OF THE INVENTION

The control system of the present invention provides for precise control of the position of a bucket in an aerial lift vehicle with respect to a high voltage calbe. This system includes a number of electro-hydraulic proportional valves of the type disclosed in the Bahnuik U. S. Pat. No. 3,311,855 issued Mar. 28, 1967, entitled "Torque Motor", and U. S. Pat. No. 3,339,573 issued Sept. 5, 1967, entitled "Flow Control Valve." This type of a valve is known to provide smooth and continuous control of the flow of hydraulic fluid. A set of electric controllers are provided on the vehicle and are actuated by fixed manually actuated levers provided in the bucket through electrically insulated push-pull assemblies mounted in the boom. The linemen in the bucket is able to obtain relatively fast speed to the general location of the desired work area and slow, precise movement of the bucket to the desired location with respect to the high voltage cable. The manually actuated levers in the bucket are fixed in order to allow the linemen to quickly and easily find the control levers in the bucket. This is accomplished by providing rotatable linear motion actuators at the pivot point between the bucket and the boom to connect the levers to the insulated assemblies. These actuators allow for rotary motion between the bucket and boom with positive response to linear movement of the manually actuated levers in the bucket. The levers are spring centered to obtain an immediate stop in movement of the bucket as soon as the lever is released by the lineman.

The hydraulic system is also provided with a lockout or position-holding arrangement to maintain the bucket in position while the linemen is working on the cable. The positive position-holding capability of this system prevents drifting of the bucket and loss of holding force due to hose failures.

DRAWINGS

FIG. 1 is an elevation view of an aerial lift vehicle showing generally the location of the mechanical control levers, electrical controllers and hydraulic system;

FIG. 2 is a perspective view partially broken away of the insulated push-pull actuators;

FIG. 3 is a cross sectional view of a section of one of a flexible insulated push-pull actuators;

FIG. 4 is a cross sectional view of the rotatable linear motion actuator for the mechanical control levers.

FIG. 5 is an exploded view of one of the rotatable linear motion actuators;

FIG. 6 is a view of an alternate rotary-linear motion device;

FIG. 7 is a side view in section of an extendible type push-pull actuator;

FIG. 8 is a cross-sectional view taken on line 8--8 of FIG. 7 showing the configuration of the inner and outer members; and

FIG. 9 is a circuit diagram of the lock-out circuit for the hydraulic valves.

DESCRIPTION OF THE INVENTION

The aerial lift vehicle of this invention generally includes a carriage 10 rotatably mounted on the platform 12 of a vehicle, a first boom section 14 pivotally connected to the carriage 10 and a second insulated boom section 16 pivotally connected to the first boom section 14. A bucket 18 is pivotally connected to the upper end of the second boom section 16. The carriage 10 is rotated by means of a hydraulic motor 20 and the booms 14 and 16 are raised and lowered by means of double-acting hydrauilc piston and cylinder assemblies 22 and 24. The second boom section 16 is insulated by means of a fiberglass section 26. In some instances, it may be desirable to also include an insulated section in the first boom section 4. The hydraulic motor 20 is controlled by means of an electro-hydraulic proportional valve 28 and piston and cylinder assemblies 22 and 24 are controlled through a hydraulic slip ring 25 by means of electro-hydraulic proportional valves 30 and 32, respectively. The operation of this type of valve is fully disclosed in the Bahnuik patents set forth above and provide for positive control in the movement of the carriage and the first and second boom sections.

ELECTRIC CONTROL

The proportional valves 28, 30 and 32 are controlled by means of a first set of electric controllers 34 provided on the first boom section 16 and a second set of electro controllers 36 connected to the proportional valves from a point remote from the valves. The controllers 34 are connected to the valves by means of an electric override switch 38 through electric lines 35 and slip ring 37. The second set of electric controllers 36 are connected to the proportional valves by means of the override switch assembly 38 through the electric lines 39. The override switch assembly 38 allows the operator on the ground to take over the operation of the bucket at any time by merely switching the assembly 38 to the override position.

The electrical control assemblies 34 and 36 each include a number of monaxial controllers 40. Each of the controllers 40 is of a conventiional type having rheostats to provide precise control of the torque motors in the proportional valves.

These controllers require very small forces to operate and thereby make it possble to use smaller actuators to control the motion of the valves.

PUSH-PULL ASSEMBLIES

In accordance with the invention, the controllers 40 in the assembly 34 are actuated by means of a set of manually actuated levers 42 mounted in the bucket 18 and a number of electrically insulated push-pull assemblies 44 operatively connecting each of the levers 42 to the corresponding monaxial controller 40. Referring to FIG. 2 each of the assemblies 44 is shown embedded in the insulated boom section 26 of the second boom section 16. Each assembly 44 includes a tubular fiberglass sleeve 46 and a fiberglass rod 48. The rods 48 are coaxially mounted within the tubes 46 and are connected at each end to push-pull cables 50 and 52. The push-pull cables 50 are used to connect the manual levers 42 to the assemblies 44 and allow for a limited amount of pivotal movement of the bucket 18 with respect to the boom 16. The push-pull cables 52 are used to connect the assemblies 44 to the corresponding controller 40 through a fixed panel 54. The push-pull cables 50 and 52 are conventional flexible type cables that will provide similar movements between one of the levers 42 and the corresponding one of the controllers 40.

ALTERNATE PUSH-PULL ASSEMBLY (FIG. 3)

In some installations, it may be desirable to use flexible type push-pull assemblies 45. A cross section of such an assembly 45 is shown in FIG. 3. Each of these assemblies includes an insulated rod 47 encased in a thin sheath 49 and wrapped in a spirally wound fiberglass 51. This type of assembly can be used in an aerial lift which has both booms 14 and 16 insulated. The assembly 45 can be wrapped around the pivot between the booms 14 and 16.

ROTARY LINEAR MOTION ACTUATOR

Means are provided for allowing the bucket 18 to rotate freely on the boom 16 while maintaining the levers 42 in a fixed position in the bucket 18.

Referring to FIGS. 4 and 5, such means includes a rotary linear motion actuator assembly 58 which connects the manual levers 42 through the pivot support 55 for the bucket 18 on the boom 16 to the cables 50. One of the actuators 60 for the control assembly 58 as seen in FIG. 5 includes a first member 62 and a second member 64 connected by a split sleeve 66. Each of the members 62 and 64 is free to rotate within sleeve 66. The linear motion of the member 62 is transferred to the member 64 through sleeve 66.

In this regard, each of the members 62 and 64 includes a flange 68 on the end of a small diameter rod 70. The sleeve 66 includes two half sections 72, each having an internal flange 74 at each end which fit in the space between the flange 68 and the end of the members 62 and 64. With this arrangement, the members 62 is free to rotate with respect to the member 64. However, any linear movement of the member 62 will be transmitted by the sleeve 66 to the member 64.

Referring to FIG. 4, the complete actuator assembly 58 is shown. The center assembly 60 described above, has the member 62 connected to one of the levers 42 by a link 61 and the member 64 connected to one of the cables 50. The second actuator 80 includes a sleeve member 82 having a radial flange 83 coaxially mounted on member 62 and a sleeve member 84 having a radial flange 85 coaxially mounted on member 64. The sleeve members 82 and 84 are interconnected by means of a sleeve 86 having a radially inwardly directed flange 88. The flanges 88 being seated in the groove behind the flanges 83 and 85. The member 82 s connected to controller 42 by means of a link 81 and the member 84 is connected to the cable 50.

The third actuator 100 is similar to the second actuator 80 having a sleeve member 102 and 104 coaxially mounted on members 82 and 84. The members 102 and 104 each include a radially outwardly extending flange 106 and 108, respectively, and are connected by a sleeve 110 having radially inwardly extending flanges 112. The member 102 is connected to the controller 42 by a link 101 and the member 104 is connected to one of the cables 50.

The rotary-linear motion actuator 58 allows members 64, 84 and 104 to rotate freely with the cables 50 while the members 62, 82 and 102 remain fixed relative to the bucket. Any linear motion of the members 62, 82 or 102 will be transferred directly to the corresponding cable 50.

ALTERNATE ROTARY-LINEAR MOTION ACTUATOR

The alternate rotary-linear motion actuator 120 (FIG. 6) connects the control levers 42 to the cables 50 by means of three coaxially arranged members 122, 124 and 126. The inner or center tubular member 122 is supported in a coaxial relation to the pivot for the bucket 18. The intermediate sleeve or member 124 is coaxially mounted on the tubular member 122 and the outer sleeve or member 126 is mounted on the intermediate member 124. The outer member 124 is supported for rotary motion on a bearing 128. The control levers 42 are secured to one end of the members 122, 124 and 126 and the other end of the members 122, 124 and 126 are connected to the cables 50 by links 130. Rotary movement of the levers 42 are transferred directly to the cables 50 through links 130.

ALTERNATE PUSH-PULL ACTUATOR FOR EXTENDABLE BOOM

In the event the booms 14 or 16 are of the extendable type, a push-pull assembly 140 as shown in FIGS. 7 and 7A can be used to control the controller 40. The assembly 140 includes a sleeve 142 and a fiberglass rod 144 having an outer square or splined contour corresponding to the inner square or splined contour 144 of the sleeves 142. The sleeve 142 is mounted for rotary motion on bearings 146 and is moved by means of a control lever 148. The rod 144 is mounted for rotary motion on bearings 150 and is connected directly to the monaxial electrical controller 40. With this arrangement, the fiberglass rod 144 is free to move linearly within the fiberglass sleeve 142 and the rotary motion of the sleeve 142 is transferred directly to the rod 144. The assembly 140 can be connected directly to the lines 130 (FIG. 6).

SELF-CENTERING CONTROL LEVERS

Means are provided for centering the control levers 42 to close the valves 28, 30 and 32 and stop the motion of the carriage 12 or booms 14 and 16. Such means as seen in FIG. 2 is in the form of a double-acting spring 23 provided on a reduced section 27 of the fiberglass rod 48. The spring 23 is located in a bore 15 in the fiberglass section 26. A washer 29 is mounted on the section 27 at one end of the bore 15 and a sleeve 31 having a flange 33 is mounted on the section 27 at the other end of the bore 15. Movement of the rod 48 to the right will compress the spring 23 between the washer 29 and sleeve 31. Movement of the rod 48 to the left will compress the spring 23 between the sleeve 33 and the washer 29.

MOISTURE SEALS

Means are provided to prevent formation of moisture within the assemblies 44 and 140. Such means is in the form of a boot 56 and O-ring seals 57 provided on each end of the rods 48. In this regard, the boots 56 are sealed to the rod 48 and to the end of the sleeve 46 to completely enclose the rod within the tube. The tube can be filled with a di-electric grease if desired. The O-ring seals 57 are provided between the section 28 and the threaded cap 59 located at each end of the section 26.

HYDRAULIC LOCK OUT CIRCUIT

Means are provided for hydraulically locking the boom and carriage in a fixed position when the levers are in a neutral position. Referring to FIG. 9, such means is shown in a hydraulic circuit 151 having hydraulic lines 152 and 154 connected to a cylinder 156 for a hydraulic assembly 158. The flow of hydraulic fluid from a pump 160 to a reservoir 162 is controlled by means of a 4-way three position control valve 164 connected across the lines 152 and 154. The control of pressure in the cylinder 156 is controlled by means of pressure actuated hydraulic bypass valve assemblies 166 and 168. The bypass valve assembly 166 includes a one-way check valve 170, serially connected in the line 152 by a line 172 and a pressure-actuated bypass valve 174, serially connected in the line 162 by a line 176, the bypass valve 174 being cross connected to the line 154 by means of a line 178. The assembly 168 includes a one-way check valve 180 serially connected in the line 154 by a line 182 and a pressure-actuated bypass valve 184 serially connected in the line 154 by a line 186, the bypass valve 184 being cross connected to the line 152 by a line 188.

In the position of the control valve 164 shown in FIG. 9, both of the lines 152 and 154 are connected directly to the reservoir 162. Both of the bypass valves 166 and 168 will be closed and both of the check valves 170 and 180 will be closed preventing any flow of hydraulic fluid from the cylinder 156 to the reservoir 162. When the control valve 164 is moved to the right, pressure will build up in line 152 and line 188, opening the check valve 170 and the bypass valve 184. Fluid will flow through the check valve 170 to the cylinder and from the cylinder through the bypass valve 184 to the reservoir. When the control valve 164 is returned to the neutral position, the pressure in lines 152 and 154 will immediately drop to reservoir pressure and the bypass valve 184 will immediately close. The pressure in the line 152 between the bypass valve assembly 166 and the cylinder 156 will remain constant because both the valve 170 and bypass valve 174 will be closed.

When the control valve 164 is moved to the left in FIG. 9, pressure will build up in line 154 and line 178, opening the check valve 180 and the bypass valve 174. Fluid will flow through check valve 180 to the cylinder 156 and from the cylinder 156 through the bypass valve 174 to the reservoir. When the control valve 164 is returned to neutral, the pressure in lines 152 and 154 will again drop to reservoir pressure.

SAFETY CIRCUIT

The electro-hydraulic proportional valves 28, 30 and 32 can also be readily connected to safety circuits in the vehicle to prevent movement of the boom until the safety circuit is closed. In this regard and referring to FIG. 1, a safety circuit 190 for the outriggers is shown connected to the override switch assembly 38. The safety circuit 190 includes four series connected cut-out switches 192 connected by an electric line 195 through a battery 194 to the override switch 38. Each cut-out switch 192 is actuated after the vehicle outriggers have been set. When all of the outriggers have been set, the switches 192 will be closed completing the circuit and activating the circuit to the valves 28, 30 and 32.

Claims

I claim:

1. An aerial lift vehicle having a carriage rotatably mounted on the vehicle,

an electrically insulated boom pivotally mounted on said carriage,

a bucket pivotally carried at the electrically insulated end of said boom,

a hydraulic system operatively connected to move said boom and said carriage, said hydraulic system including,

a number of electro-hydraulic proportional valves mounted on the vehicle,

a first set of electric monoaxial controllers mounted on said boom for controlling said valves, said controllers being electrically connected to said electro-hydraulic valves,

a number of manually actuated levers mounted in said bucket,

and a number of electrically insulated push-pull assemblies operatively connecting each of said levers to a corresponding electric monaxial controller.

2. The hydraulic system according to claim 1 including a second set of electric monaxial controllers connected to said valves at a point remote from said valves.

3. The hydraulic system according to claim 2 including means for connecting said second set of electric monaxial controllers to override said first set of electric monaxial controllers.

4. The hydraulic system according to claim 1 wherein each of said insulated push-pull assemblies includes a fiberglass sleeve mounted on said boom and a fiberglass rod mounted for axial movement within said sleeve.

5. An aerial lift vehicle having a carriage rotatably mounted on the vehicle,

an electrically insulated boom pivotally mounted on said carriage,

a bucket pivotally carried at the electrically insulated end of said boom,

a hydraulic system operatively connected to move said boom and said carriage, said hydraulic system including,

a number of electro-hydraulic proportional valves,

a first set of electric controllers mounted on said boom for controlling said valves,

a number of manually actuated levers mounted in said bucket,

a number of electrically insulated push-pull assemblies operatively connecting each of said levers to a corresponding electric controller,

and a number of rotary linear actuators coaxially mounted at the pivot point of said bucket on said boom and operatively connecting said manual levers to said insulated push-pull assemblies.

6. The hydraulic system according to claim 5 wherein said rotary linear motion actuators each includes a first member connected to a manual lever, a second member connected to said insulated push-pull assembly, and a sleeve operatively connected to said first and second members, said sleeve allowing for rotary motion between said members.

7. The hydraulic system according to claim 6 wherein each of said rotary-linear motion actuators is coaxially mounted with respect to each of the other rotary-linear motion actuators.

8. An aerial lift vehicle including a boom having an electrically insulated boom section, said boom being mounted for articulated movement of said vehicle,

a bucket mounted on the insulated end of said boom,

means for pivotally mounting said bucket on said boom,

a hydraulic system for moving said boom, said system including,

electro-hydraulic proportional valves mounted on said vehicle,

an electric monaxial controller mounted on said boom and being electrically connected to control said proportional valves,

a manually actuated lever mounted in a fixed position in said bucket,

and an electrically insulated push-pull assembly operatively connecting said lever to the monaxial controller.

9. The vehicle according to claim 8 wherein said bucket mounting means includes a rotary-linear actuator connecting said lever to said push-pull assembly.

10. The vehicle according to claim 8 including a second controller operatively connected to said valve at a point remote from said valve and means connecting said second controller to override said first controller.

11. The vehicle according to claim 9 wherein said rotary-linear motion actuator includes an input member connected to said lever, an output member connected to said assembly and a sleeve operatively connecting said input member to said output member to allow for rotary motion between said input and output members.

12. The vehicle according to claim 8 including a safety circuit connected to control said overriding means.

13. The vehicle according to claim 8 wherein said hydraulic system includes a hydraulic assembly connected to move said boom ad controlled by said valve, and means connected to said assembly for locking said assembly in a fixed position when said valve is in a neutral position.

14. The vehicle according to claim 13 wherein said locking means includes a pressure actuated bypass valve assembly connected to each end of said hydraulic assembly, said valve assemblies being cross connected to respond to pressure in the other of said bypass assemblies.