JP3066994U - Boom raising operation control device for work vehicles - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To eliminate a shock generated when the telescopic boom is moved upside down from a raised state. A boom raising operation restricting device (30) includes a boom operating device (21) for operating a raising / lowering cylinder (13), a raising / lowering angle sensor (31) for detecting a raising / lowering angle of a telescopic boom, and an operation control valve for controlling the operation of the raising / lowering cylinder (13). And a controller 33 for controlling the controller 35. Controller 33
Is a stroke calculation circuit 41 that calculates a stroke length of the undulating cylinder 13 according to an angle signal of the undulating angle sensor 31.
A comparison determination circuit 43 that determines whether the calculated stroke length is on a stroke end side that exceeds a predetermined position on the near side of a stroke end on the extension side of the up-and-down cylinder 13, and a stroke determined by the comparison determination circuit 43. If it is determined that the length exceeds the predetermined position,
3 has an operation restricting circuit 37 for restricting the extension operation.

Description

[Detailed description of the invention]

[0001]

[Technical field to which the invention belongs]

 The present invention relates to a boom raising operation control device for a work vehicle, and more specifically, a work vehicle having a boom provided on a vehicle body so as to be able to move up and down, and an up / down cylinder for moving the boom up and down with respect to the vehicle body. Boom raising operation control device.

[0002]

[Prior art]

 An aerial work vehicle that performs aerial work is configured to include a telescopic boom provided on a vehicle body so as to be able to extend, retract, turn, and raise and lower, and a work table provided at a tip end of the telescopic boom. There is something. The telescopic boom is pivotally connected to a swivel provided on the vehicle body so as to be rotatable, and an up / down cylinder is pivotally connected between the swivel and the lower surface of the telescopic boom. Is configured to undulate. A telescopic cylinder is built in the telescopic boom, and when the telescopic cylinder is telescopically operated, the telescopic boom is telescopically operated. Further, a turning motor is built in the vehicle body below the turning table, and when the turning motor is operated, the turning table is turned. For this reason, the workbench can be moved to a desired position by operating the telescopic cylinder, the up / down cylinder, and the turning motor.

[0003]

[Problems to be solved by the invention]

 However, the operation of the undulating cylinder is controlled so that the entire stroke can be used. When the undulating cylinder is contracted from the fully extended state (hereinafter referred to as the “up-and-down operation end state”), the undulating cylinder is moved. The shrinking speed changes suddenly, causing a shock to the stretching boom, making the rider on the platform uncomfortable.

[0004] When the up-and-down cylinder is brought into the up-and-down operation end state, a part of the tip of the piston provided at the tip of the cylinder rod comes into close contact with the inside of the end face of the cylinder tube. When hydraulic oil is supplied to the rod chamber of the up / down cylinder at the tip of the piston, the area of hydraulic pressure acting on the piston is small, so only a small force acts on the piston, and the up / down cylinder moves down at a low speed. However, when the piston moves slightly due to this small force, the piston that has been in close contact with the inside of the end surface of the cylinder tube separates from the end surface, and the area of hydraulic pressure acting on the piston increases rapidly. As a result, a large force acts on the piston to move the piston at a high speed, and the undulating cylinder contracts. For this reason, since the contraction speed of the telescopic boom changes rapidly, an acceleration is generated and a shock is generated in the telescopic boom.

[0005] In order to prevent a shock from occurring due to a sudden contraction of the up-down cylinder in the up-down operation end state, supply of hydraulic oil supplied to the up-down cylinder at the start of the up-down operation of the telescopic boom. Methods for reducing the speed have already been proposed. According to this method, the opening of a hydraulic oil supply valve provided downstream of a hydraulic circuit connected to an up-and-down cylinder is increased from a certain opening to a certain degree. If the temperature of the hydraulic oil is low at the start of the fall operation, the viscosity of the hydraulic oil increases and the fluidity decreases, so the flow rate of the hydraulic oil is small at the start of the fall operation and the hydraulic oil supply valve is opened. Hydraulic oil flows suddenly at a certain point where the degree has increased. For this reason, there is a problem that the shrinking speed of the undulating cylinder may suddenly change to cause a shock to the telescopic boom.

The present invention has been made in view of such a problem, and prevents the occurrence of a shock due to a sudden change in the contraction speed of the up / down cylinder when the telescopic boom is caused to fall from the up / down operation end state. An object of the present invention is to provide a boom raising operation control device for a work vehicle.

[0007]

[Means for Solving the Problems]

 In order to solve the above-mentioned problem, a boom raising operation control device for a working vehicle according to the present invention raises and lowers a boom (for example, a telescopic boom 11 in the embodiment) provided on a vehicle body so as to be able to move up and down. A boom raising / lowering operation restricting device for a working vehicle having an up-and-down cylinder (for example, an aerial work vehicle 1 in the embodiment), wherein an up-and-down angle detecting means for detecting an up-and-down angle of the boom with respect to a vehicle body (for example, in the embodiment) And a restricting means (for example, an operation restricting circuit 45 in the embodiment) for stopping the extension operation of the hoist cylinder at less than the maximum hoisting angle at which the boom is raised from the detected value of the hoisting angle detecting means. Have.

According to the boom raising operation restricting device, when the raising / lowering cylinder extends and the boom raises, the raising / lowering angle detecting means detects the raising / lowering angle of the boom with respect to the vehicle body. The detected value is sent to the regulating means, and the regulating means compares the detected value with the maximum undulation angle, and stops the extension operation of the undulating cylinder when the detected value is less than the maximum undulation angle.

For this reason, since the extension operation of the undulating cylinder is restricted before the stroke end on the extension side, the extension operation is stopped before the stroke end (hereinafter, referred to as “regulated extension state”). )), The shrinking speed of the undulating cylinder is not sharply changed and the occurrence of a shock can be prevented.

[0010] The boom raising operation control device for a work vehicle according to the present invention is a boom raising device for a work vehicle having an up-and-down cylinder that raises and lowers a boom mounted on a vehicle body so as to be able to move up and down. A lift operation restricting device which is configured to raise the boom by extension operation of an up-and-down cylinder, and a stroke length detecting means for detecting a length of a stroke of the up-and-down cylinder (for example, an up-and-down angle in the embodiment). Sensor 31 and stroke calculation circuit 41) and the extension operation of the up / down cylinder to the stroke end side where the detection value detected by the stroke length detecting means exceeds a predetermined position on the near side of the extension side of the up / down cylinder. It has a stroke regulating means for regulating (for example, the operation regulating circuit 45 in the embodiment).

[0011] According to the boom raising operation restricting device, when the raising / lowering cylinder is extended, the stroke length detecting means detects the stroke length of the raising / lowering cylinder. The detected value is sent to the stroke restricting means, and based on the detected value, the stroke restricting means moves up and down to the stroke end side beyond a predetermined position on the front side of the extension end stroke end of the up / down cylinder. Restricts cylinder extension operation.

For this reason, since the extension operation of the undulating cylinder is regulated before the stroke end on the extension side, when the undulating cylinder is contracted from the restricted extension state, a rapid change in the contraction speed of the undulating cylinder is limited. And the occurrence of shock can be prevented.

[0013]

[Embodiment of the invention]

 Hereinafter, a preferred embodiment of the present invention will be described with reference to FIGS. This embodiment shows an embodiment of an aerial work vehicle in which the telescopic boom moves up and down when the up-and-down cylinder is extended. First, before describing the boom raising operation restricting device of the work vehicle of the present invention, an aerial work vehicle equipped with the boom raising operation restricting device will be described.

As shown in FIG. 1, the aerial work vehicle 1 has an outrigger jack 5 for stably supporting the vehicle body 3 in front and rear of the vehicle body 3, and projects upward at a rear upper portion of the vehicle body 3 to pivot. A free-turn table 7 is provided. A turning motor 9 is built in the vehicle body 3 below the turning table 7, and the turning table 9 is turned by the operation of the turning motor 9. The base of the telescopic boom 11 is pivotally connected to the upper part of the swivel base 7, and an up-and-down cylinder 13 is pivotally connected between the lower surface of the telescopic boom 11 and the bottom of the swivel base 7. The boom 11 is configured to perform an up / down operation. A telescopic cylinder 15 is provided in the telescopic boom 11, and the telescopic boom 11 is configured to be telescopically operated by telescopically operating the telescopic cylinder 15. A not-shown leveling mechanism is provided at the distal end of the telescopic boom 11. By operating the leveling mechanism, a vertical swinging mechanism is provided at the distal end of the telescopic boom 11 so as to be vertically swingable regardless of the elevation angle of the telescopic boom 11. The post 17 is always kept vertical. At the side of the vertical post 17, a work table 19 on which an operator can board is mounted.

A boom operating device 21 for operating the telescopic boom 11 is provided inside the workbench 19. When the operating lever L provided on the boom operating device 21 is manually operated, the boom is turned according to the operation amount. The motor 9, the up-and-down cylinder 13, and the telescopic cylinder 15 are operated to move the workbench 19 to a desired position.

Next, the boom raising operation restricting device of the present invention will be described with reference to FIG. The boom raising operation restricting device 30 includes a boom operating device 21, a raising and lowering angle sensor 31, a controller 33, an operation control valve 35, and a raising and lowering cylinder 13. Since the boom operation device 21 has been described above, its description is omitted. The undulation angle sensor 31 has a function of detecting the undulation angle of the telescopic boom 11 with respect to the vehicle body 3, and a potentiometer can be used. The undulation angle sensor 31 is not limited to the one described above, and a ground angle detection sensor that detects an inclination angle with respect to the ground on which the vehicle is mounted may be used. In this case, a vehicle body inclination angle sensor for detecting the inclination angle of the vehicle body 3 with respect to the ground is attached to the vehicle body 3, and the vehicle body inclination detection value detected by the vehicle body inclination angle sensor is detected by the vehicle body inclination angle detection sensor. Then, the undulation angle of the telescopic boom 11 is calculated. However, when the vehicle body 3 is held substantially horizontally by the grounding of the outrigger jack 5, it is not necessary to correct the vehicle body inclination angle.

The controller 33 shown in FIG. 2 controls the operation of the operation control valve 35 based on the operation signal of the boom operating device 21 to control the extension operation of the up-and-down cylinder 13, and outputs the angle signal of the up-and-down angle sensor 31. It has a function of restricting the extension operation of the undulating cylinder 13 accordingly. More specifically, the controller 33 controls the opening of the operation control valve 35 based on an operation signal corresponding to the operation amount of the operation lever L of the boom operation device 21 to adjust the flow rate of the operation oil. 37, an extension operation determining circuit 39 for determining whether or not the operation performed by the boom operating device 21 is an extension operation for extending the up-and-down cylinder 13, and an angle signal from the up-and-down angle sensor 31. A stroke calculation circuit 41 for calculating the length of the stroke of the up-and-down cylinder 13, and a stroke length calculated by the stroke calculation circuit 41 is a predetermined position (hereinafter referred to as “the stroke end”) on the extension side of the up-down cylinder 13. Stretch limit position ”.) A comparison judgment circuit 43 for comparing and judging whether or not the stroke length is from the stroke end side. When determining the stroke end side hair Rukoto from the long limit position, is configured to have a working inhibition circuit 45 for regulating the extension operation of the derricking cylinder 13.

The operation control valve 35 is electrically connected to the controller 33 and communicates with the up / down cylinder 13 in the hydraulic circuit 47. As shown in FIG. 3, the hydraulic circuit 47 has a supply oil passage 49 and a return oil passage 51, and the tank T, the hydraulic pump P, the operation control valve 35, the holding valve 55, the up-and-down cylinder 13 It is configured with The hydraulic pump P is rotationally driven by the driving force of an engine E provided in the vehicle, discharges hydraulic oil stored in the tank T to a supply oil passage 49, and supplies the hydraulic control oil to the operation control valve 35. The operation of the operation control valve 35 is controlled by the controller 33 shown in FIG. 2, but in addition to adjusting the flow rate of the hydraulic oil supplied from the hydraulic pump P, the supply direction of the hydraulic oil supplied to the hoisting cylinder 13 is switched. Or have the function of shutting off supply. The operation control valve 35 is an electromagnetic two-position switching valve. In its neutral position, a supply oil passage 49 between the bottom chamber 13a of the hoist cylinder 13 and the hydraulic pump P and a return oil passage between the rod chamber 13b and the tank T are provided. 51. The holding valve 55 has a function of preventing the up-and-down cylinder 13 from suddenly shrinking even when the supply oil passage 49 downstream of the holding valve 55 is damaged and hydraulic oil in the supply oil passage 49 leaks out.

The holding valve 55 has a check valve 57 and a pressure control valve 59 arranged side by side. The pilot oil pressure in the return oil passage 51 is taken on the primary side of the pressure control valve 59, and when the primary pressure reaches the set pressure, a spring is set. By overcoming the bias of 61, the flow of hydraulic oil from the hoist cylinder 13 side to the operation control valve 35 side in the supply oil path 49 is allowed. When the primary pressure is lower than the set pressure, the pressure control valve 59 is closed, and the hydraulic oil discharged from the hydraulic pump P is allowed to flow into the bottom chamber 13a of the up-and-down cylinder 13 through the check valve 57. I do. The undulating cylinder 13 is a double-acting cylinder, and the supply oil passage 49 communicates with the bottom chamber 13a, and the return oil passage 13b communicates with the rod chamber 13b.

Next, the operation of the boom raising operation restricting device 30 of the present invention will be described. First, in a state where the outrigger jack 5 and the telescopic boom 11 are stored in the vehicle body 3 shown in FIG. 1, the vehicle is moved to a work site, and then a worker (not shown) projects the outrigger jack 5 and removes the tip thereof. The vehicle body 3 is stably supported by grounding. Then, the operator gets on the work table 19 and manually operates the operation lever L of the boom operation device 21. When the operator operates the operation lever L, an operation signal corresponding to the operation amount of the operation lever L is sent to the controller 33 shown in FIG. 2, and based on the operation signal, the operation control circuit 37 operates the operation control valve shown in FIG. The opening of the cylinder 35 is adjusted to a predetermined opening, and the operation control valve 35 is switched from the neutral state to allow the supply of the hydraulic oil discharged from the hydraulic pump P to the bottom chamber 13a of the up-and-down cylinder 13. When the operation control valve 35 is switched, the rod chamber 13b of the undulating cylinder 13 communicates with the tank T through the operation control valve 35. Therefore, the hydraulic oil discharged from the hydraulic pump P flows into the bottom chamber 13a of the undulating cylinder 13 via the operation control valve 35 and the check valve 57, and the hydraulic oil in the rod 13b of the undulating cylinder 13 is returned to the return oil. It flows through the road 51 and flows out to the tank T. For this reason, the undulating cylinder 13 extends.

An operation signal generated from the boom operating device 21 shown in FIG. 2 is sent to an extension operation determination circuit 39 of the controller 33, and the extension operation determination circuit 39 determines that the content of the operation signal is an extension operation of the undulating cylinder. Is determined, and the extension operation determining circuit 39 activates the operation restricting circuit 45 based on the determination result. The operation control circuit 45 operates the operation control valve 35 based on the determination result from the comparison determination circuit 43. That is, the stroke calculation circuit 41 calculates the length of the stroke of the undulating cylinder 13 based on the angle signal from the undulation angle sensor 31, and based on the calculated stroke length, the comparison determination circuit 43 determines that the stroke length is the extension limit position. Is determined to be on the stroke end side, and the determination result is sent to the operation restriction circuit 45. When the operation restricting circuit 45 receives the determination result when the stroke length is from the extension limit position to the stroke end side, the operation restricting circuit 45 controls the operation control valve 35 to restrict the extension operation of the up-and-down cylinder 13. The state is switched to the neutral state, the supply oil passage 49 is shut off, and the supply of the hydraulic oil discharged from the hydraulic pump P to the bottom chamber 13a is shut off.

As a result, even when the operator operates the boom operating device 21 to continue raising the telescopic boom 11, the operation restricting circuit 45 extends the extension cylinder 13 before the stroke end of the up-and-down cylinder 13. Can be stopped.

When the telescopic boom 11 is moved down by moving the undulating cylinder 13 down from the state in which the undulating cylinder 13 is extended just before the stroke end, the operator operates the operating lever of the boom operating device 21. Operate L. When the operation lever L is operated, the operation signal is sent to the operation control circuit 37 of the controller 33 and the extension operation determination circuit 39. Upon receiving the operation signal, the operation control circuit 37 controls the opening degree of the operation control valve 35 based on the content of the signal, and switches the method of the flow of the hydraulic oil, thereby changing the hydraulic pump P and the rod of the up-and-down cylinder 13. The chamber 13b is communicated and the tank T and the bottom chamber 13a of the hoisting cylinder 13 are communicated. As a result, the hydraulic oil discharged from the hydraulic pump P flows into the rod chamber 13b through the operation control valve 35 and the return oil passage 51, and the hydraulic oil in the bottom chamber 13a releases the pressure released by the pilot pressure of the feedback circuit. It is discharged to the tank T via the control valve 59 and the operation control valve 35. For this reason, the up-and-down cylinder 13 contracts.

The hydraulic oil that has flowed into the rod chamber 13b presses the rear surface of the piston 14a of the cylinder rod 14 of the undulating cylinder 13, but since the cylinder rod 14 is in front of the extension stroke end, the rear surface of the piston 14a is It is exposed in the chamber 13b. Therefore, the hydraulic oil flowing into the rod chamber 13b acts on the entire rear surface of the piston 14a to exert a large force on the piston 14a. Then, the magnitude of the force acting on the piston 14a does not change. As a result, the cylinder rod 14 moves toward the bottom chamber 13a at a constant speed, so that no shock is generated in the telescopic boom 11.

In the above-described embodiment, the extension operation of the up / down cylinder 13 is restricted before the stroke end in the direction in which the up / down cylinder 13 is extended. The reduction operation of the cylinder 13 may be restricted. In this case, instead of the extension operation determination circuit 39 shown in FIG. 2, a reduction operation determination circuit that determines whether or not the content of the operation signal sent from the boom operation device 21 is a reduction operation of the up / down cylinder 13 is provided. use. In addition, the comparison determination circuit 43 determines that the stroke length calculated by the stroke calculation circuit 41 is a stroke from a predetermined position (hereinafter, referred to as a “reduction limit position”) closer to the front than the stroke end of the reduction cylinder 13 on the reduction side. A comparison is made to determine whether or not there is an end. Further, the operation restricting circuit 45 restricts the retracting operation of the up-and-down cylinder 13 when the comparison determination circuit 43 determines that the stroke length is from the reduction limit position to the stroke end side. Further, in the above-described embodiment, the up-and-down operation of the telescopic boom 11 has been described. However, the cylinder used for the telescopic operation of the telescopic boom 11, the bending / extending operation of the bending / extension type boom, and the telescopic operation of the outrigger jack 5 is also described above. The operation can be applied in the same manner as in the embodiment described above.

With this configuration, when the up-down cylinder 13 is extended from the state in which the up-down cylinder 13 is reduced just before the stroke end on the reduction side and the telescopic boom 11 is raised, the extension speed of the up-down cylinder 13 is increased. Does not change abruptly and does not shock the telescopic boom. In the above-described embodiment, the stroke length of the up / down cylinder 13 is calculated by the stroke calculation circuit 41 shown in FIG. 2. However, an extension sensor that directly detects the stroke length of the up / down cylinder 13 can be used. In this case, when the comparison determination circuit 43 determines that the stroke length detected by the extension sensor is from the reduction limit position to the stroke end, the reduction operation of the undulating cylinder 13 is restricted.

Further, a potentiometer or a limit switch can be used as the undulation angle sensor 31. When a potentiometer is used, the up / down angle of the telescopic boom 11 and the output voltage of the potentiometer are made to correspond in advance, and when the output voltage of the potentiometer just before the stroke end of the up / down cylinder 13 is detected, the height of the up / down cylinder 13 is detected. Stop the extension operation. When the limit switch is used, the limit switch is configured to be turned ON when the undulating cylinder 13 is extended to a predetermined position just before the stroke end of the undulating cylinder 13, and the undulation is linked to the ON operation. The extension operation of the cylinder 13 is stopped.

Further, in the so-called boom-end shockless processing, in which the expansion and contraction operation of the up-and-down cylinder 13 approaches the stroke end, the expansion and contraction speed of the up-and-down cylinder is reduced to reduce the shock generated in the telescopic boom. The process and the control for stopping the extension operation of the up-and-down cylinder 13 before the stroke end described above can be used together.

Further, in the boom raising operation restricting device 30 described above, the maximum raising and lowering angle at which the telescopic boom 11 raises and lowering is set in advance, and the raising and lowering angle detection value and the maximum raising and lowering angle detected by the raising and lowering angle sensor 31 are set. And the extension operation of the up / down cylinder 13 can be restricted so that the detected value of the up / down angle is less than the maximum up / down angle. In this case, in the controller 33 shown in FIG. 2, the maximum undulation angle at which the telescopic boom 11 is raised is set in advance, and the detected undulation angle is compared with the maximum undulation angle. An undulation angle determination circuit for determining that the angle is less than the threshold value is provided. When the undulation angle detection circuit determines that the undulation angle detection value is less than the maximum undulation angle, the operation restriction circuit operates to restrict the extension operation of the undulation cylinder 13. Here, “less than the maximum undulation angle” refers to the undulation angle of the telescopic boom 11 corresponding to a predetermined position on the near side of the stroke end on the extension side of the undulation cylinder 13.

With this configuration, the up-and-down cylinder 13 does not extend beyond the stroke end on the extension side, and does not extend beyond the stroke end. , The up-and-down cylinder 13 contracts at a constant speed, so that no shock is generated in the telescopic boom 11.

[0031]

[Effect of the invention]

 As described above, according to the work vehicle boom elevating operation restricting device of the present invention, the boom elevates from the detected value of the boom elevating angle detecting means for detecting the angle of the boom with respect to the vehicle body, and the boom elevating means. By providing a restricting means for stopping the extension operation of the undulating cylinder at less than the maximum undulating angle, the extension operation of the undulating cylinder is regulated shortly before the stroke end on the extension side. The extension cylinder does not extend beyond the stroke end, and when the extension cylinder is contracted from the state in which the extension operation is stopped before the stroke end, the cylinder is contracted at a constant speed. Therefore, it is possible to maintain the ride comfort of the worker in a good condition even if the worker gets on the tip of the boom without causing any shock.

Further, according to the working vehicle boom raising operation restricting device of the present invention, the detection value detected by the stroke length detecting means for detecting the length of the stroke of the up-and-down cylinder is the stroke on the extension side of the up-and-down cylinder. When the stroke exceeds the predetermined position on the front side of the end, the stroke regulating means regulates the extension operation of the undulating cylinder toward the stroke end, whereby the same effect as the first aspect can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view of an aerial work vehicle equipped with a boom raising operation restricting device according to an embodiment of the present invention.

FIG. 2 is a block diagram of the boom raising operation restricting device according to the embodiment of the present invention.

FIG. 3 shows a hydraulic circuit for operating the up-and-down cylinder in one embodiment of the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 work platform (work vehicle) 3 body 11 telescopic boom (boom) 13 up / down cylinder 21 boom operation device (up / down cylinder operation / operation means) 30 boom up / down operation control device 31 up / down angle sensor (stroke length detection means, up / down angle) Detection means) 41 Stroke calculation circuit (Stroke length detection means, Stroke length calculation means) 45 Operation restriction circuit (Regulation means, Stroke restriction means)

Claims (2)

[Utility model registration claims] 1. A boom raising / lowering operation restricting device for a work vehicle having a raising / lowering cylinder for raising / lowering a boom provided on a vehicle body so as to be movable up and down, wherein the boom is raised and lowered with respect to the vehicle body. Work comprising: an undulation angle detection means for detecting an angle; and a restriction means for stopping the extension operation of the undulation cylinder when the detected value of the undulation angle detection means is less than a maximum undulation angle at which the boom is raised. Car boom raising operation restriction device. 2. A boom raising / lowering operation restricting device for a work vehicle having a raising / lowering cylinder for raising / lowering a boom movably provided on a vehicle body with respect to the vehicle body, wherein a stroke length of the lifting cylinder is long. A stroke length detecting means for detecting the stroke length of the up-and-down cylinder to the stroke end side where a detection value detected by the stroke length detecting means exceeds a predetermined position on the front side of a stroke end on the extension side of the up-and-down cylinder. A boom raising operation restricting device for a working vehicle, comprising a stroke restricting means for restricting an extension operation.