JP2015132226A - Speed control device for hydraulic actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a speed control device for a hydraulic actuator capable of changing-over a high engine speed and a low engine speed, easily performing this changing-over operation and preventing trouble from being generated.SOLUTION: This invention comprises a cam device 1 including a control valve V for controlling an operation speed of a winch motor M, an accelerator for controlling an increased or decreased number of revolution of an engine E, a manual operation lever Lw for controlling a hydraulic oil changing-over direction and a valve opening degree at the control valve V, a cam part 2 for transmitting a motion of the operation lever Lw to the accelerator, and an accelerator roller 5. The cam part 2 comprises a high-speed cam 10 for moving the accelerator roller 5 a little and a normal cam 20 for moving the accelerator roller 5 widely. Since the high-speed cam 10 and the normal cam 20 are different from each other in view of amount for moving the accelerator roller 5, selection of any one of them enables the engine speed to be increased or decreased in a high range or in a low range.

Description

  The present invention relates to a speed control device for a hydraulic actuator. More particularly, the present invention relates to an apparatus for controlling the speed of an actuator for a work machine that operates a hydraulic actuator with a hydraulic pump and drives the hydraulic pump with an engine. The present invention can be applied to any industrial actuator as long as it is a working machine using a hydraulic actuator as described above.

  In the working machine using the hydraulic pump driven by the engine as described above, the speed control of the hydraulic actuator is performed by controlling two elements of the valve opening amount of the hydraulic actuator control valve and the engine speed for rotating the hydraulic pump. Yes.

Since it is troublesome for the operator to manually control the valve opening amount and the engine speed of the control valve individually, a technology that can simultaneously operate the valve opening degree and the engine speed with one operating lever has already been developed. It was being developed.
However, in this prior art, if the valve opening is increased, the engine speed increases in conjunction with it, which is not preferable because the fuel consumption increases and the noise increases, and the operating speed of the hydraulic actuator becomes faster than necessary, There was also a problem that it was difficult to perform a fine movement operation.

Therefore, in order to solve this problem, the conventional technique of Patent Document 1 has been proposed.
In this prior art, the valve operating lever is moved forward and backward in the axial direction with respect to the accelerator operating link of the engine, and the engaging position between the engaging portion and the engaging receiving portion is changed. With this prior art, even if the switching valve is immediately changed in response to the movement of the operating lever, the accelerator operating link can be operated with a delay, even if the valve operating lever is moved to the end position. The upper limit of the engine speed can be limited. That is, the engine speed can be switched between high and low.

  However, the above prior art uses a structure for changing the insertion length of the shaft and the cylindrical portion and a mechanism for changing the engagement position between the engagement portion and the engagement receiving portion around the shaft, and is incorporated in the link mechanism. It's a complicated structure. For this reason, there is a problem that troubles are likely to occur, and handling is troublesome in that the amount of play between the engagement portion and the engagement receiving portion must be adjusted manually.

By the way, in the winch which is a kind of working machine, a high-speed winch using a high-speed hydraulic motor has already been used. In addition, there are several types of high-low speed hydraulic motors such as a swash plate type piston motor and an eccentric type motor, which have already been put into practical use, but are very expensive because the production quantity is still small.
Furthermore, if such a high-low speed hydraulic motor is used and speed control is to be performed automatically, a controller and many sensors are required, resulting in a high equipment cost.
For this reason, for small work machines such as truck-mounted cranes, products that automatically control the speed have not yet become widespread.

Utility Model Registration Gazette No. 2528724

  In view of the above circumstances, an object of the present invention is to provide a speed control device for a hydraulic actuator that is capable of switching between a high speed and a low speed of a hydraulic actuator and that is simple and hardly causes a failure. It is another object of the present invention to provide a speed control device for a hydraulic actuator that uses a simple manual device and can perform speed control at a low cost.

According to a first aspect of the present invention, there is provided a hydraulic actuator speed control apparatus, comprising: a control valve that controls an operating speed of the hydraulic actuator in a working machine that operates a hydraulic actuator for a working machine with a hydraulic pump and drives the hydraulic pump with an engine; A rotation speed controller for increasing / decreasing the rotation speed of the engine, a manual operation lever for directly controlling a pressure oil switching direction and a valve opening degree in the control valve, and a movement of the operation lever are transmitted to the rotation speed controller. A cam device comprising a cam and a cam follower, the cam device comprising: a high-speed cam that moves the cam follower small; a normal cam that moves the cam follower large; the high-speed cam; and the normal cam The cam surface of the high speed cam or the normal cam is in a position where one of them is pushed out. Characterized in that comprising a position fixing mechanism is fixed at the operating position to move the serial cam follower.
The speed control device for a hydraulic actuator according to a second aspect of the present invention is the speed control device for the hydraulic actuator according to the first aspect, wherein the high speed cam is fixed to a base end portion of the operation lever, and the normal cam is the high speed cam. The position fixing mechanism is a two-position holding notch that can hold the position at the forward position and the backward position of the normal cam.
According to a third aspect of the present invention, in the first or second aspect, the hydraulic actuator is a high / low speed variable motor, and the high speed / low speed variable motor has a high / low speed mode for the high speed cam or the normal cam. It is characterized in that a switch actuator for operating a changeover switch for switching between the two is provided.
The hydraulic actuator speed control device according to a fourth aspect of the present invention is the speed control device for the hydraulic actuator according to the third aspect, wherein the switch actuator is a push piece formed on the normal cam, and the change-over switch is located when the normal cam is in the operating position. It is the thing which operates.
A speed control device for a hydraulic actuator according to a fifth aspect of the present invention is the speed control device for a hydraulic actuator according to the third aspect, wherein the switch actuator is a switch operation plate, is slidably attached to the cam follower at the cam portion, and is attached to the cam follower. It is biased toward.

According to the first invention, when one of the high speed cam and the normal cam is pushed and pulled, the cam surface of the cam can be fixed at the operating position. Since the amount of movement of the cam follower is different between the high speed cam and the normal cam, the engine rotational speed can be increased or decreased in the high region or increased or decreased by selecting one of the cams. In addition, the cam device has a structure in which two cams are overlapped and has a simple structure with a small number of parts, so that failure is unlikely to occur and low cost can be realized. Moreover, it can be retrofitted to an existing working machine by replacing the cam device.
According to the second aspect of the invention, the cam follower can be moved by the normal cam when the normal cam is moved forward, and the cam follower can be moved by the high speed cam when the normal cam is moved backward. Since the forward position and the backward position of the normal cam can be held by the two-position holding notch, the speed of the hydraulic actuator can be reliably controlled without causing the normal cam to malfunction during the lever operation.
According to the third aspect of the invention, when the high speed cam or the normal cam is selected, the high / low speed variable motor is automatically switched to the high speed mode or the low speed mode by the switch actuator, so that the mode change is simple.
According to the fourth invention, when the normal cam is set to the operating position, the high / low speed mode of the high / low speed variable motor can be switched by operating the changeover switch with the push piece.
According to the fifth aspect of the invention, the high / low speed mode of the high / low speed variable motor can be switched by operating the changeover switch with the switch operation plate.

It is a perspective view around the cam device in the speed control device of the present invention. 1 is a hydraulic circuit diagram of a winch motor that is an example of a hydraulic actuator to which the present invention is applied. The cam apparatus which concerns on 1st Embodiment is shown, (A) is a perspective view which shows the surface side, (B) is a perspective view which shows a back surface side. (A) is explanatory drawing of the cam for high speed, (B) is explanatory drawing of the cam for normal. It is usage explanatory drawing by the cam for high speeds. The cam apparatus which concerns on 2nd Embodiment is shown, (A) is a perspective view which shows the surface side, (B) is a perspective view which shows a back surface side. (A) is explanatory drawing of a cam for normal use, (B) is usage explanatory drawing. (A) is explanatory drawing of the cam for high speed, (B) is usage explanatory drawing. It is a relation explanatory view of lever operation amount and hook speed in the speed control device of a 1st embodiment. It is a relationship explanatory drawing of the lever operation amount and hook speed in the speed control device of a 2nd embodiment. It is a side view of the small crane which is an example of a working vehicle. It is a front view of the small crane of FIG.

Next, an embodiment of the present invention will be described with reference to the drawings.
First, a truck-mounted crane is taken as an example of a working vehicle to which the present invention is applied, and its basic structure will be described.
11 and 12, CP is a crane post, B is a multistage boom, F is a hook, and J is an outrigger jack. The crane post CP turns on the swivel, the boom B moves up and down with the hoisting cylinder Cy, and expands and contracts with a boom built-in telescopic cylinder (not shown).
The hook F is moved up and down by winding and lowering the wire rope with a winch W attached to the crane post CP.

The multistage boom B, the hook F, the outrigger jack J, the winch W, and the like described above are examples of the working machine referred to in the claims. Further, the telescopic cylinder, the undulation cylinder, the winch motor, the jack cylinder, and the like are examples of the hydraulic actuator referred to in the claims.
Each of these hydraulic actuators is connected to a known hydraulic circuit including a hydraulic pump, a hydraulic control valve, a tank and the like. The hydraulic control valve can switch the pressure oil feed direction and adjust the valve opening with a plurality of manual operation levers Lv shown in FIG.

In the following embodiments, a speed control device in which the present invention is applied to a winch motor will be described.
FIG. 1 shows the operation lever Lw around the winch motor M. FIG. This operation lever Lw is one of the plurality of manual operation levers Lv shown in FIG.
A cam portion 2 is attached to the base portion of the operation lever Lw. The cam portion 2 is supported by the vertical axis 4 so that the operation lever Lw can be tilted left and right around the vertical axis 4.
A cylindrical cam follower 5 is disposed facing the cam portion 2, and the cam follower 5 is supported by a link 6 and a support shaft 7 and is swingably attached around the support shaft 7. The cam portion 2 and the cam follower 5 constitute a cam device 1 as defined in the claims.

There are various types of rotation speed controllers referred to in the claims, but the accelerator is typical. Therefore, in the following embodiments, the accelerator is the control object, and the cam follower 5 referred to in the claims is provided. A description will be given of the accelerator roller 5 that adjusts the accelerator of the engine.
An arm 8 is attached to the lower portion of the support shaft 7 so as to extend radially outward, and an accelerator wire 9 connected to the arm 8 is connected to an accelerator for controlling the engine speed of the work vehicle. . For this reason, when the accelerator roller 5 swings and the accelerator wire 9 is pushed and pulled, the engine speed increases and the discharge amount of the hydraulic pump also increases and decreases, and the drive speed of the hydraulic actuator increases and decreases.

  On the other hand, the left and right tilting of the operating lever Lw is connected to the spool end of a hydraulic control valve V for winch motor control (shown in FIG. 2) by a dedicated link or the like. Can be controlled.

Next, a hydraulic circuit of the winch motor M that is a target of speed control will be described with reference to FIG.
M is a winch hydraulic motor (hereinafter referred to as a winch motor), and a known hydraulic circuit comprising a hydraulic control valve V, a hydraulic pump P, and a tank T is used for forward and reverse rotation of the winch motor M.

  The winch motor M is a high and low speed hydraulic motor, and is a known hydraulic actuator that can select two modes of a low speed rotation mode and a high speed rotation mode. The low-speed rotation mode can output low-speed and high-torque compared to the high-speed rotation mode.

  The high-low speed mode can be switched by changing the eccentric angle of the rotor if the winch motor M is a radial type, or by a known means such as changing the tilt angle of the drive shaft and the cylinder block if it is an axial type. The switching of the winch motor M between the high speed mode and the low speed mode is performed by the switching cylinder Cm, and a solenoid-operated on-off valve Vm is provided to control expansion and contraction of the switching cylinder Cm. The solenoid S is connected to a power source via the changeover switch 40. This changeover switch 40 is attached to the cam portion 2 described in detail later.

  The hydraulic pump P is rotationally driven by the engine E of the work vehicle, and the engine speed is increased or decreased by the accelerator A. The engine speed is controlled through the accelerator wire 9 pushed and pulled by the operation lever Lw shown in FIG. 1 as described above.

(First embodiment)
Next, the cam portion 2 in the first embodiment will be described with reference to FIGS.
As shown in FIG. 3, the cam portion 2 includes a high-speed cam 10 and a normal cam 20. The high-speed cam 10 is a plate material bent into a U shape in a side view, and a base portion thereof is attached to a base portion of the operation lever Lw. The cam plate of the high-speed cam 10 is formed with a hole 11 and a guide groove 12 through which the support shaft 4 is passed.
The high-speed cam 10 may be fixed to the support shaft 4 that passes through the hole 11 so that the support shaft 4 is rotatable. The support shaft 4 is fixed, and the high-speed cam 10 (and thus the cam portion) around the hole 11. 2) may be tilted to the left and right.
The guide groove 12 is curved, and the guide shaft 3 shown in FIG. 1 passes through the guide groove 12, thereby guiding the tilting of the cam portion 2 in the left-right direction and restricting the stroke end.

  As shown in FIG. 4A, the profile of the cam surface 13 of the high-speed cam 10 is composed of a non-control surface 14 at the center and rotation speed control surfaces 15 and 15 on both sides thereof. The non-control surface 14 is a portion that does not control the engine speed. While the non-control surface 14 is in contact with the accelerator roller 5, the hydraulic system is operated by the link system dedicated to opening and closing the valve connected to the operation lever Lw. The switching direction and valve opening degree of the control valve V are controlled.

  The rotational speed control surfaces 15 and 15 on both sides of the cam surface 13 are parts for controlling the rotational speed of the engine E shown in FIG. 2, and when the rotational speed control surfaces 15 and 15 push the accelerator roller 5, the arm 8 swings. The accelerator wire 9 is pushed and pulled to increase or decrease the engine speed.

As shown in FIG. 4B, the normal cam 20 is slidably attached to the back surface of the high-speed cam 10. The normal cam 20 has a shape similar to that of the high-speed cam 10 and has a curved guide groove 22, a switch actuator 26, and a finger ring 27.
The guide groove 22 is formed wider than the guide groove 12 of the high speed cam 10, and the guide shaft shown in FIG. 1 is shown when the normal cam 20 is pushed out to the operating position and retracted to the non-operating position. 3 is allowed.

The switch operator 26 is an operator that turns the changeover switch 40 on and off. When the normal cam 20 is pushed out to the operating position, the switch operator 26 pushes and operates the changeover switch 40. .
The finger ring 27 can hook a human finger and is provided to push and pull the normal cam 20 with the human hand.

  The profile of the cam surface 23 of the normal cam 20 is composed of a non-control surface 24 at the center and rotation speed control surfaces 25 and 25 on both sides thereof. The non-control surface 24 is a portion that does not control the engine speed, and while the non-control surface 24 pushes the accelerator roller 5, the hydraulic control valve is connected to the above-described link system dedicated to opening and closing the valve connected to the operation lever Lw. The switching direction of V and the valve opening are controlled.

  The rotational speed control surface 25 of the normal cam 20 is a part for controlling the rotational speed of the engine E shown in FIG. 2, and the cam surface is higher than the rotational speed control surface 15 of the high-speed cam 10 described above. . That is, it is possible to increase the engine speed by largely pushing and pulling the accelerator wire 9.

Three guide pins 17 are planted on the back surface of the high-speed cam 10, and two guide long holes 28 and one notch long hole 29 are provided on the cam plate of the normal cam 20. Yes. The two guide pins 17 are fitted into two guide slots 28 and serve as slide guides. A two-position holding notch 29n is formed in the notch long hole 29, and one guide pin 17 is fitted in the two-position holding notch 29n. The two-position holding notch 29n has a function of allowing the guide pin 17 to move between the two holes by a slight elastic deformation and holding the guide pin 17 in the hole.
Therefore, the normal cam 20 can be manually changed between the cam operating position and the non-operating position, and can be held so that the cam does not move arbitrarily at any position. For this reason, malfunction can also be prevented. This mechanism is a position fixing mechanism referred to in the claims.

Next, the speed switching procedure by the cam device 1 comprising the cam portion 2 and the accelerator roller 5 will be described.
(Normal operation)
As shown in FIG. 4B, the normal cam 20 is pushed out to the operating position. In this case, normal operation is possible between the low speed range and the high speed range as described below.
(1) Selection of cam When the normal cam 20 is pushed out, its cam surface 23 protrudes from the cam surface 13 of the high-speed cam 10 and becomes an operating position for pushing the accelerator roller 5.
At this time, the non-control surfaces 14 and 24 have the same height in both the normal cam 20 and the high-speed cam 10, but the rotation speed control surface 25 of the normal cam 20 is higher than the rotation speed control surface 15 of the high-speed cam 10. It has become.

(2) High / low changeover switch When the switch actuator 26 pushes the changeover switch 40 and turns it on simultaneously with the pushing out of the normal cam 10, the changeover cylinder Cm shown in FIG. 2 operates and the winch motor M outputs high torque at a low speed. Switch to low speed mode.

(3) Operation In the above situation, when the operation lever Lw is moved and the normal cam 20 is moved left and right, normal operation is possible.
The contents of the normal operation will be described with reference to FIG.
In the upper graph in FIG. 9A, the vertical axis indicates the flow rate, and the horizontal axis indicates the lever pull amount S of the operation lever Lw.
The middle graph shows the valve opening of the hydraulic control valve V, and the lower graph shows the engine speed. The area below the point A on the horizontal axis is the valve opening degree control area, and the area above the point A is the engine speed control area.
The engine speed (thin line e1) shown in the lower graph keeps a constant rotation (idle state) of 800 rpm below the point A, increases linearly after the point A, and reaches 2000 rpm. The valve opening (thin line v) of the hydraulic control valve V shown in the middle graph increases linearly from the 0 point to the B point where the opening is slightly larger than the A point, and after the B point the same opening (the valve passing at this time) The flow rate changes at, for example, 20 L).

Next, the contents of normal operation will be described based on the upper graph.
When the control lever Lw is moved small in the area below the point A, that is, while the non-control surface 14 is in contact with the accelerator roller 5, the hydraulic control valve V is switched in both forward and reverse directions by a dedicated link system, and the valve opening amount Increase or decrease. In this case, the flow rate is controlled only by the valve opening, and the flow rate flowing into the winch motor M varies between 0 and 20 L / min, for example. For this reason, the winch speed is low, and a fine movement operation for moving the hook F at a low speed is possible.

  Then, when the operating lever Lw is moved largely in the region beyond the point A and the accelerator roller 5 is pushed on the rotational speed control surface 15, the accelerator roller 5 moves greatly as the lever pulling amount is increased, and the moving amount of the accelerator wire 9 is increased. growing. For this reason, the engine speed can be increased linearly from an idle state (800 rpm) to, for example, 2000 rpm, and the hydraulic oil discharge amount of the hydraulic pump P can be increased from, for example, 20 L / min to 60 L / min.

In this case, the winch motor M is supplied with hydraulic oil at a maximum of 60 L / min, for example, and the hook F can be moved at, for example, 19 m / min as indicated by the thick solid line fs. Further, in this normal operation, high torque can be output and heavy objects can be lifted.
Since the engine speed increases, noise and the like increase.

(High speed operation)
As shown in FIG. 5B, the normal cam 20 is retracted and the high-speed cam 10 is set to the operating position. In this case, high-speed operation is performed at a low flow rate.
(1) Selection of cam When the normal cam 20 is pulled back to bring the high-speed cam 10 into the operating position, the cam surface 23 of the normal cam 20 is lower than the cam surface 13 of the high-speed cam 10 (Note: the same There may be a height part).

(2) High / low changeover switch When the normal cam 20 is retracted, the switch actuator 26 is separated from the changeover switch 40 and turned OFF. For this reason, the winch motor M is switched to the high speed mode that outputs low torque at high speed.

(3) Operation In the above situation, when the operation lever Lw is moved and the high speed cam 10 is moved left and right, high speed operation is possible.
The contents of the high speed operation will be described with reference to FIG.
Since the cam surface 13 of the high-speed cam 10 is low, the amount of movement of the accelerator roller 5 is small even when the operation lever Lw is rotated to the left or right. For this reason, as indicated by a thin line e2 in the lower graph of FIG. 9B, the engine speed increases only to 1400 rpm, for example. Compared with the dotted line e1 indicating the engine speed during normal operation (maximum 2000 rpm), it is about 3/4.

  When the control lever Lw is moved small below the point A, that is, while the non-control surface 24 is in contact with the accelerator roller 5, the engine speed is idling (800 rpm), and the flow rate flowing into the winch motor M is, for example, Increase or decrease linearly up to 20 L / min. However, since the winch motor M in the high-speed mode rotates at a small amount of oil, the hook speed fs is fast. For this reason, if the load is light, it can be raised and lowered quickly, but fine movement operation is difficult instead.

  On the other hand, when the operating lever Lw is moved beyond the point A, the engine speed increases, so the flow rate also increases. However, since the rotation speed is suppressed to 1400 rpm at the maximum, the flow rate is also suppressed to 40 L / min at the maximum.

In the high-speed mode, as described above, the winch motor M has a high rotational speed even at a small flow rate, so that a high hook speed fs (for example, 19 m / min at the same maximum as in normal operation) can be maintained after the point A.
In this case, since the engine speed is kept low, noise and the like are suppressed. This mode is suitable for work in urban areas and at night.
When the winch motor M is in the high speed mode, the output of the winch W does not become a high torque, so if it is a light load, it can be used for winding it.
As described above, although the hook speed is the same as the conventional one, the engine speed can be reduced and the fuel consumption can be suppressed. It is also effective for suppressing an increase in the oil temperature of the hydraulic system.

(Second Embodiment)
The cam apparatus 1 of 2nd Embodiment is demonstrated based on FIGS.
The high speed cam 10 and the normal cam 20 constituting the cam portion 2 shown in FIG. 6A are the same as those in the first embodiment. The present embodiment is characterized in that a switch actuator is not formed on the normal cam 20 and a switch operating plate 30 dedicated to switch switching operation is provided. A push piece 31 for turning the changeover switch 40 on and off is formed on the switch operating plate 30.

  As shown in FIG. 6B, the switch operating plate 30 is disposed on the back surface of the normal cam 20 and is slidably attached to the guide pin 17 through a long hole (not shown). Further, although it is always pushed out to the accelerator roller 5 side by an appropriate biasing means (not shown) such as a spring, it is pushed back by the accelerator roller 5 when it comes into contact with the accelerator roller 5.

Next, the speed switching procedure by the cam device 1 of the second embodiment will be described.
(Normal operation)
As shown in FIG. 7, the normal operation is performed by pushing the normal cam 20 to the operating position. In this case, normal operation is possible from the low speed range to the high speed range.
FIG. 7A shows a state in which the non-control surface 24 of the normal cam 20 is used. In this case, the operation by adjusting the valve opening by the operation lever Lw is performed below the point A in FIG. 9A. Is called. FIG. 7B shows a state in which the rotational speed control surface 25 is used. In this case, an operation is performed by increasing or decreasing the engine rotational speed at point A or higher in FIG. 9A.
Details of such operation are the same as those of the first embodiment described above.

(High speed operation)
As shown in FIG. 8B, the normal cam 20 is retracted and the high-speed cam 10 is set to the operating position. In this case, high speed operation is performed.
(1) Selection of cam When the normal cam 20 is pulled back to bring the high-speed cam 10 into the operating position, the cam surface 23 of the normal cam 20 becomes lower than the cam surface 13 of the high-speed cam 10 (Note: the same height) May be part).

(2) High / low change-over switch When the normal cam 20 is retracted by manual operation, the switch operation plate 30 is in a position protruding toward the accelerator roller 5, so that when it is pushed back by the accelerator roller 5, the switch is operated. The push piece 31 of the plate 30 pushes the changeover switch 40 and is turned ON. Therefore, the winch motor M is switched to the high speed mode that outputs high speed and low torque.

(3) Operation As shown in FIG. 8A, in the state where the accelerator roller 5 is pushed by the non-control surface 14 of the high speed cam 10, the operation below the point A in FIG. 10 is performed. In this case, since the winch motor M is still in the low speed mode, the speed of the hook F (thick solid line fs1) is not fast. For this reason, it is easy to perform fine movement operation.

  Next, as shown in FIG. 8B, when the operating lever Lw is moved and the high-speed cam 10 is moved left and right beyond the non-control surface 14, the switch operating plate 30 is pushed down by the accelerator roller 5, and the changeover switch 40 is turned on. When operated, the winch motor M can be operated at high speed.

The contents of the high speed operation will be described with reference to FIG.
Since the cam surface 13 of the high-speed cam 10 is low, the amount of movement of the accelerator roller 5 is small even when the cam portion 2 is largely rotated left and right. For this reason, as indicated by the thin line e2 in the lower graph of FIG. Compared to the thin line e1 (indicated by the dotted line) indicating the engine speed (maximum 2000 rpm) during normal operation, it is about 3/4.

  While the control lever Lw is moved slightly below the point A and the non-control surface 14 is pushing the accelerator roller 5, it is the same as in the normal operation. That is, the engine speed is in an idling state (800 rpm), and the flow rate flowing into the winch motor M linearly increases or decreases up to, for example, 20 L / min.

However, when the operation lever Lw is tilted greatly as shown in FIG. 8B, the accelerator roller 5 moves the switch operating plate 30, and the push piece 31 switches the changeover switch 40 to ON by this movement, so that the winch motor M Is in high-speed mode.
In this way, when the engine is moved beyond the point A shown in the upper graph of FIG. 10, the engine speed increases, so the flow rate also increases. However, since the rotation speed is suppressed to 1400 rpm at the maximum, the flow rate is also suppressed to 40 L / min at the maximum.
In the high-speed mode, since the rotation speed of the winch motor M is high even at a small flow rate, the speed of the hook F (thick solid line fs2) can maintain a high speed (for example, 19 m / min at the same maximum as the normal operation) after the point A.

Even if the hook speed fs2 is increased as described above, the engine speed can be suppressed lower than that speed, so noise and the like are suppressed. This mode is suitable for work in urban areas and at night.
When the hydraulic motor M is in the high speed mode, the output of the winch W does not become a high torque, so if it is a light load, it can be used for winding it.
As described above, while the hook speed is the same as that in the normal operation, the engine speed can be reduced and fuel consumption can be suppressed. It is also effective for suppressing an increase in the oil temperature of the hydraulic system.

(Example)
Next, examples will be described.
The specifications of the winch motor M in this embodiment are as follows.
The standard for switching the high and low speed motor M is normal mode operation when the load is 1.7 t or more, and high speed mode operation when the load is 1.7 t or less.

<Normal mode operation with a load of 1.7 tons or more>
Cam: Normal cam 20
High and low speed motor capacity: 23.6cc / rev
Maximum engine speed: 2000rpm
Maximum hook speed: 19m / min
<High-speed mode operation with a suspended load of 1.7 t or less>
Cam: Cam 10 for high speed
High and low speed motor capacity: 14.7cc / rev
Maximum engine speed: 1400rpm
Maximum hook speed: 19m / min

  As described above, when the load is 1.7 t or less, the hook speed is the same as that in the normal operation, but the engine speed can be reduced and the fuel consumption can be suppressed. It is also effective for suppressing an increase in the oil temperature of the hydraulic system.

(Other embodiments)
In each of the above embodiments, the high-speed cam 10 is fixed to the operation lever Lw. Instead, the normal cam 20 is fixed to the lever 1 and the high-speed cam 10 is slidably attached to the normal cam 20. Also good.
In this case, a switch actuator 26 for operating the changeover switch 40 may be attached to the high-speed cam 10.

  According to the present invention, even a truck-mounted crane that does not have a control device can be equipped with a high and low speed winch easily and inexpensively. In addition, since the present invention can be retrofitted simply by replacing the cam device 1 at the lever operation portion of the winch, the time required for adding specifications to the existing working machine can be reduced.

  Since the cam device 1 used in the present invention has a simple structure based on the two cams 10 and 20, the number of parts is small and failure is unlikely to occur.

In the above embodiment, the present invention is applied to a winch of a truck-mounted crane. However, the present invention can be applied to various other industrial machines and hydraulic working machines incorporated in those industrial machines.
The present invention can be used not only for a truck equipped with a crane but also for an automobile transport vehicle, an aerial work vehicle, and the like.

DESCRIPTION OF SYMBOLS 1 Cam apparatus 2 Cam part 4 Vertical axis | shaft 5 Accel roller 9 Accel wire 10 High speed cam 13 Cam surface 14 Non-control surface 15 Rotation speed control surface 20 Normal cam 23 Cam surface 24 Non-control surface 25 Rotation speed control surface 26 Switch operation Child 30 Switch operating plate 40 Changeover switch M Winch motor P Hydraulic pump E Engine V Hydraulic control valve

Claims (5)

In a working machine that operates a hydraulic actuator for a working machine with a hydraulic pump and drives the hydraulic pump with an engine,
A control valve for controlling the operating speed of the hydraulic actuator;
A rotational speed controller for increasing or decreasing the rotational speed of the engine;
A manual operation lever for directly controlling the pressure oil switching direction and the valve opening in the control valve;
A cam for transmitting the movement of the operation lever to the rotation speed controller and a cam device comprising a cam follower;
The cam device includes a high-speed cam that moves the cam follower small and a normal cam that moves the cam follower greatly;
The high-speed cam and the normal cam are overlapped with each other, and the position where the cam surface of the high-speed cam or the normal cam is fixed to the operating position for moving the cam follower at the position where one of the cams is pushed out. A hydraulic actuator speed control device comprising a mechanism. In the cam device, the high-speed cam is fixed to a base end portion of the operation lever,
The normal cam is slidably attached to the high-speed cam;
2. The speed control device for a hydraulic actuator according to claim 1, wherein the position fixing mechanism is a two-position holding notch capable of holding the position at the forward position and the backward position of the normal cam. The hydraulic actuator is a high-low speed variable motor;
3. The hydraulic actuator speed control device according to claim 1, wherein a switch actuator for operating a changeover switch for switching the high-low speed mode of the high-low speed variable motor is provided on the high-speed cam or the normal cam. . The switch actuator is a push piece formed on the normal cam;
4. The speed control device for a hydraulic actuator according to claim 3, wherein the change-over switch is operated when the normal cam is in the operating position. 4. The switch actuator according to claim 3, wherein the switch actuator is a switch operation plate, is slidably attached to the cam follower at the cam portion, and is biased toward the cam follower. Hydraulic actuator speed control device.