JPS6342657Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a traveling speed control device for a wheeled hydraulic excavator, and particularly to a device that can perform good speed control.

<Prior Art> Fig. 1 is a side view showing the external appearance of a wheeled hydraulic excavator to which the present invention is applied, and Fig. 2 is a basic configuration of a traveling hydraulic circuit included in the wheeled hydraulic excavator shown in Fig. 1. Circuit diagrams illustrating Figures 3 and 4
The figures are explanatory diagrams showing the main parts of a conventional traveling speed control device, with FIG. 3 being a side view showing the accelerator pedal-related parts, and FIG. 4 being a side view showing the operating lever-related parts.

First, a wheel type hydraulic excavator and a traveling hydraulic circuit will be briefly explained with reference to FIGS. 1 and 2. In FIG. 1, 1 is an upper rotating body;
Reference numeral 2 denotes a working device attached to the upper revolving structure 1, which is composed of a boom, an arm, a bucket, etc., and is used to perform excavation work, etc. Reference numeral 3 denotes a lower traveling body located below the revolving upper structure 1, and has wheels 4. The wheels 4 are operated by a hydraulic motor 5 for traveling.

Further, in FIG. 2, 5 is the aforementioned hydraulic motor, 7 is a variable displacement hydraulic pump that drives this hydraulic motor 5, and 6 is a drive source that drives this variable displacement hydraulic pump 7, that is, an engine. Reference numeral 8 denotes a traveling direction switching valve disposed between the hydraulic motor 5 and the variable displacement hydraulic pump 7, and 9 is an operating lever for switching the traveling direction switching valve 8. Although not shown in FIG. 2, the traveling direction switching valve 8 is connected with other direction switching valves to form one multiple valve, and for this multiple valve, one An operating lever 9 is arranged. Therefore, the operating lever 9 is used as a travel lever, a turning lever, etc. depending on the type of directional control valve constituting the multiple valve. In FIG. 2, 10 is a counter balance valve, 11 is a relief valve, and 12 is a clutch valve, and this clutch valve 12 is connected to the hydraulic motor 5 during braking.
Bypass the hydraulic oil supplied to the Also 12
A is a conduit that guides brake pressure to the clutch valve 12.

And the third one, which shows the conventional traveling speed control device.
In Figure 4, 13 is the accelerator pedal, and the floor 13
A is rotatably fixed to the engine 6, and is provided to control the output, that is, the rotational speed of the engine 6 during driving. 14 is a rod whose one end is fixed to the accelerator pedal 13 so as to be rotatable therebetween; 15 is a rod 14;
A rotatable lever 16 is connected at one end to the lever 15 and a spring 17 is connected to the lever 15 at one end so as to be rotatable therebetween. The rod 18 is an accelerator lever which is rotatable and is provided to control the rotational speed of the engine 6 during excavation work. 19
is a link having two elongated holes, into which a pin provided at the other end of the rod 17 and a pin provided at the lower end of the accelerator lever 18 are loosely fitted. 20 is a rod whose one end is connected to the link 19; 21 is a fuel lever whose other end is rotatably connected to the rod 20, and which is itself rotatable;
It is fixed to the engine 6 and controls the rotation speed of the engine 6. 9 is the aforementioned operating lever;
Reference numeral 22 is a rod rotatably connected to the operating lever 9, and reference numeral 8 is the aforementioned driving direction switching valve. The spool 23 of the traveling direction switching valve 8 is connected to the rod 22 and has a concave cam 23a at its end. As mentioned above, the traveling direction switching valve 8 constitutes one multi-unit valve together with other direction switching valves, and the other direction switching valves are also connected to the spool 23 of this running direction switching valve 8.
The cam 23a has a configuration similar to that of the cam 23a. 25 is a rotatable lever, and has a roller 24 at one end. This roller 24 is
Cam 23 of spool 23 of travel direction switching valve 8
a, and the cams of the spools of other directional control valves constituting the same multiple valve.
26 is a spring that biases the lever 25 in the clockwise direction in FIG. 4; 27 is a rod whose one end is connected to the lever 25 so as to be rotatable therebetween; and 28 is a rod whose other end is rotatable between the two ends. It is connected and fixed to the variable displacement hydraulic pump 7 described above with a regulator lever that is itself rotatable.

In addition, the above-mentioned rod 22, the traveling direction switching valve 8 having the spool 23, other direction switching valves of the same multiple valves, the lever 25, the spring 26,
The rod 27 and the regulator lever 28 are connected to the variable displacement hydraulic pump 7 according to the operation of the operating lever 9.
This constitutes a discharge capacity control means for controlling the discharge capacity of the pump.

In the case of the conventional traveling speed control device configured in this way, by changing the degree of depression of the accelerator pedal 13 during driving, and by changing the degree of rotation of the accelerator lever 18 during excavation work etc. The fuel lever 21 can be rotated as appropriate via the link 19 and the rod 20, thereby increasing or decreasing the rotational speed of the engine 6. And when driving, the control lever 9
By operating the travel direction switching valve 8, the lever 25 is rotated via the cam 23a of the spool 23 and the roller 24, and the rod 27 is rotated.
The regulator lever 28 is rotated appropriately via the
The discharge capacity of the variable displacement hydraulic pump 7 increases or decreases.

7 and 8 are characteristic diagrams illustrating the characteristics of the conventional traveling speed control device described above, respectively. FIG. 7 shows the engine rotation speed N and pump discharge amount Q when the regulator lever angle θ is constant. FIG. 8 is a characteristic diagram showing the relationship between the regulator lever angle θ and the pump discharge amount Q when the engine speed N is constant. As is clear from these figures, generally the engine speed N
The accelerator angle α is proportional to The angle α and the traveling speed V of the hydraulic shovel have a proportional relationship as shown in FIG.

In a hydraulic excavator having such a traveling speed control device, the following operations are performed at the time of starting.

That is, first, the engine 6 is idled, and then a brake pedal (not shown) is stepped on. As a result, the wheel 4 shown in FIG. 1 is fixed, and the brake pressure is transmitted to the clutch valve 12 via the conduit 12a shown in FIG. The position can be switched. Next, the operating lever 9 is operated, thereby switching the travel direction switching valve 8. In this state, the pressure oil of the variable displacement hydraulic pump 7 is supplied to the clutch valve 12.
Bypass at In addition, with the switching operation of the travel direction switching valve 8, the lever 2 shown in FIG.
5 rotates, which causes the regulator lever 2 to rotate.
8 rotates, and the discharge capacity of the variable displacement hydraulic pump 7 becomes maximum. Next, an operation is performed to return the brake pedal (not shown). As a result, the wheels 4 are free to rotate, the clutch valve 12 is returned to the position shown in FIG. 2, and the hydraulic motor 5
Pressure oil from a variable displacement hydraulic pump 7 is supplied to the pump. As a result, the hydraulic motor 5 is driven and the wheels 4
rotates, and the hydraulic excavator starts running. In addition, to adjust the driving speed, press the accelerator pedal 1.
3 to rotate the fuel lever 21 and control the rotational speed of the engine 6.

<Problems to be Solved by the Invention> By the way, the conventional traveling speed control device described above has the following problems.

(1) When starting the hydraulic excavator, press the operating lever 9.
When the regulator lever 28 is operated, the variable displacement hydraulic pump 7 reaches its maximum discharge capacity, and the accelerator pedal 1 is rotated as shown in FIG.
The initial speed is high even without pressing 3, which can lead to a sudden start, which is dangerous.

(2) The brake pedal is depressed when the vehicle is temporarily stopped, such as when waiting at a traffic light, but the operating lever 9 remains in operation during this time, so the discharge capacity of the variable displacement hydraulic pump 7 is maintained at its maximum, thus reducing energy loss. big.

The present invention was developed in view of the actual situation in the prior art, and its purpose is to provide a wheel-type hydraulic pump that can minimize the discharge capacity of a variable-displacement hydraulic pump when starting and when stopping temporarily such as waiting at a traffic light. An object of the present invention is to provide a traveling speed control device for a shovel.

<Means for Solving the Problems> In order to achieve this object, the present invention provides a variable displacement hydraulic pump, a regulator lever for controlling the discharge capacity of the variable displacement hydraulic pump, and a regulator lever for controlling the discharge capacity of the variable displacement hydraulic pump. Discharge capacity control means comprising another rotatable lever connected to the lever via a rod and having a roller at its end that abuts the spool of the travel directional valve, and a drive source for driving the variable displacement hydraulic pump. , an accelerator pedal that controls the rotation speed of this drive source, and a hydraulic motor that is driven by the discharge oil of the variable displacement hydraulic pump and operates the wheels of the lower traveling body, In a travel speed control device for a wheeled hydraulic excavator that controls the rotation speed of a hydraulic motor by controlling the amount of rotation, the rotational force of the accelerator pedal is transmitted as the rotational force of another lever of the discharge volume control means. In addition to providing another possible rod, the shape of the surface portion of the spool of the travel direction switching valve that the roller comes into contact with is configured to include a straight portion extending along the moving direction of the spool.

<Example> Hereinafter, a traveling speed control device for a wheeled hydraulic excavator according to the present invention will be explained based on the drawings. FIG. 5 is a side view showing essential parts of an embodiment of the present invention, and FIG. 6 is a partially enlarged sectional view taken along the line A-A in FIG. In addition, in these FIGS. 5 and 6, the same members as those described above are indicated by the same reference numerals.

In FIG. 5, 29 is a rod, and one end thereof is connected to the lever 15 so as to be rotatable therebetween. 31
is a joint loosely fitted to the other end of the rod 29, and the lever 25 mentioned above is connected to the joint 31 so as to be rotatable therebetween, as shown in FIG. 3
1a is a ring provided so as to be able to engage with a step formed at the end of the rod 29 and to come into contact with the end of the joint 31, and 30 is a spring that biases this ring 31a. Reference numeral 32 denotes a spool of the travel direction switching valve 8, and the end 32a that the roller 24 comes into contact with has a surface shape that does not cause the lever 25 to rotate regardless of the movement of the rod 22, that is, the movement of the spool 32. There is. That is, the shape of the surface portion of the end portion 32a of the spool 32 that is in contact with the roller 24 is formed into a shape including a direct portion extending along the moving direction of the spool, for example, a cylindrical shape. Note that the driving directional control valve 8 constitutes one multi-unit valve together with other directional control valves as in the past, but the spools of the other directional control valves are the same as in the conventional case, that is, the cam 23a shown in FIG. has been formed. The other configurations are the same as the conventional traveling speed control device shown in FIGS. 3 and 4.

In one embodiment configured in this way,
When the operating lever 9 is operated when starting or traveling, the spool 32 of the travel direction switching valve 8 moves via the rod 22, but the end 32a that the roller 24 comes into contact with is cylindrical. Therefore, the lever 25 does not rotate, and accordingly, the regulator lever 28 does not rotate at all, and the discharge capacity of the variable displacement hydraulic pump 7 shown in FIG. 2 is kept at a minimum. When the accelerator pedal 13 is depressed when the vehicle starts or runs, the lever 15 rotates via the rod 14, thereby pulling the rod 17 and the rod 29 to the left in FIG. When the rod 17 is towed, the rod 20 is towed via the link 19, which causes the fuel lever 21 to rotate.
The rotational speed of the engine 6 shown in FIG. 2 tends to increase. When the rod 29 is towed, the joint 31 moves to the left in FIG. 6 via the spring 30 and the ring 31a, as shown in FIG. Rotate counterclockwise. As the lever 25 rotates, the rod 27 is pulled to the left in FIG. Capacity tends to increase. Therefore, the rotational speed of the hydraulic motor 5 shown in FIG. 2 increases. After the regulator lever 28 reaches its maximum position, when the accelerator pedal 13 is subsequently depressed, the rods 17 and 2
9 is further pulled to the left in FIGS. 5 and 6. At this time, although the spring 30 continues to contract as the rod 29 is pulled, the lever 25 does not rotate. On the other hand, as the rod 17 is towed, the fuel lever 21 further rotates, and the rotational speed of the engine 6 shown in FIG. 2 further increases. Note that 33 in FIG. 5 indicates the control range of the regulator lever 28.
4 indicates the control range of the fuel lever 21, that is, the engine rotation speed control range.

FIG. 10 is a characteristic diagram showing the relationship between the accelerator angle α obtained by the above-described operation and the traveling speed V of the hydraulic excavator. In this Figure 10, 3
5 indicates the control range of the regulator lever 28, and 36 indicates the control range of the fuel lever 21, that is, the engine speed control range. As shown in FIG. 10, when the accelerator pedal 13 is not depressed, for example when starting or when stopping temporarily such as waiting at a traffic light, the engine speed is at its lowest, and the engine speed is at its lowest, and the engine speed is at its lowest when the accelerator pedal 13 is not depressed. The flow rate of pressure oil and the minimum. Therefore, the traveling speed V of the hydraulic excavator becomes extremely slow. Further, the adjustment range of the traveling speed V using the accelerator pedal 13 can be set to a sufficiently wide range.

Note that during work such as excavation work, the same operations as in the past are performed.

That is, when the accelerator lever 18 is operated, the fuel lever 21 rotates via the link 19 and the rod 20, and the rotation speed of the engine 6 increases. In other words, the lever 15 does not operate,
Therefore, the regulator lever 28 does not rotate. In addition, when the operating lever 9 is operated, the spool of another working direction switching valve (not shown) connected to the running direction switching valve 8 via the rod 22 moves. Since a cam similar to the conventional one, that is, a cam 23a shown in FIG. 4 is formed, the lever 25 rotates via the roller 24, thereby rotating the regulator lever 28. The discharge capacity of the variable displacement hydraulic pump 7 increases, allowing desired work to be performed. At this time, joint 31 is connected to rod 29.
Since the rod 29 is loosely fitted in the fuel lever 21, the rod 29 is not pulled regardless of the rotation of the lever 25, and does not affect the rotation of the fuel lever 21 in any way.

<Effects of the invention> Since the invention is configured as described above,
The discharge capacity of the variable displacement hydraulic pump can be minimized when starting or temporarily stopping at traffic lights, etc.
This makes it possible to reduce the initial speed when starting, thereby improving safety compared to conventional methods, and also has the effect of suppressing energy loss during temporary stops compared to conventional methods. be.

[Brief explanation of drawings]

FIG. 1 is a side view showing the external appearance of the wheeled hydraulic excavator to which the present invention is applied; FIG. 2 is a circuit diagram showing the basic configuration of the traveling hydraulic circuit included in the wheeled hydraulic excavator shown in FIG. 1; Figures 3 and 4
The figures are explanatory diagrams showing the main parts of a conventional traveling speed control device, in which Fig. 3 is a side view showing the accelerator pedal-related parts, Fig. 4 is a side view showing the operating lever-related parts,
FIG. 5 is a side view showing essential parts of an embodiment of the traveling speed control device for a wheeled hydraulic excavator according to the present invention, FIG. 6 is an enlarged cross-sectional view of a portion taken along the line A-A in FIG. Each figure is a characteristic diagram illustrating the characteristics of a conventional traveling speed control device, and FIG. 10 is a characteristic diagram illustrating the characteristics of an embodiment of the present invention shown in FIG. DESCRIPTION OF SYMBOLS 1... Upper revolving body, 2... Working device, 3... Lower traveling body, 4... Wheels, 5... Hydraulic motor, 6...
...Engine (drive source), 7...Variable displacement hydraulic pump, 8...Directional switching valve for travel, 9...Operation lever, 13...Accelerator pedal, 13a...Floor, 1
4, 17, 20, 22, 27, 29... Rod,
15, 25... Lever, 16, 26, 30... Spring, 18... Accelerator lever, 19... Link,
21... Fuel lever, 23, 32... Spool,
23a...Cam, 24...Roller, 28...Regulator lever, 31...Joint, 31a...
...Ring, 32a... end.

Claims (1)

[Scope of utility model registration request] A variable displacement hydraulic pump, a regulator lever that controls the discharge capacity of the variable displacement hydraulic pump, and a regulator lever that is connected to the regulator lever via a rod and whose end abuts the spool of the travel direction switching valve. a discharge capacity control means comprising another rotatable lever having a roller; a drive source for driving the variable displacement hydraulic pump; an accelerator pedal for controlling the rotational speed of the drive source; It is equipped with a hydraulic motor that is driven by the oil discharged from the pump and operates the wheels of the lower traveling body, and by controlling the discharge amount of the variable displacement hydraulic pump, the rotation speed of the hydraulic motor is controlled and the travel speed is controlled. In the traveling speed control device for a wheeled hydraulic excavator, there is provided another rod capable of transmitting the rotational force of the accelerator pedal as the rotational force of the other lever of the discharge volume control means, and the traveling speed of the wheeled hydraulic excavator is 1. A running speed control device for a wheeled hydraulic excavator, characterized in that a surface portion of a spool of a directional control valve is configured to include a straight line portion extending along the moving direction of the spool.