JPH10311302A - Hydraulic equipment for cargo handling vehicles - Google Patents

Abstract

(57) [Problem] In a cargo handling vehicle that uses a traveling internal combustion engine as a power source and performs cargo handling using hydraulic pressure, the engine speed is increased to increase noise and cause energy loss. The present invention provides a hydraulic device that does not require any pressure. A hydraulic pressure source is a variable hydraulic pressure supply source capable of freely changing the discharge amount per unit rotation, and an operation amount detection means for detecting an operation amount of an operation means for operating actuators. And a rotation speed detection means 6 for detecting the rotation speed of the internal combustion engine 2, and a discharge control means 8 for controlling the discharge amount of the variable hydraulic pressure supply source 3. The discharge amount of the variable hydraulic pressure supply source is increased within a range not exceeding the set discharge amount of the pressure supply source 3, and when the rotation speed detected by the rotation speed detection means falls below a predetermined rotation speed, the variable hydraulic pressure supply source is The discharge amount was not increased further.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic device for cargo handling work using a traveling internal combustion engine as a power source in a cargo handling vehicle such as a truck crane.

[0002]

2. Description of the Related Art Conventionally, in an engine vehicle for cargo handling work represented by a truck crane or the like, a hydraulic actuator such as a hydraulic motor or a hydraulic cylinder is used for work related to hoisting such as turning of a crane or hoist winch. Many are used. The operation of these hydraulic actuators is performed by generating pressure oil by a hydraulic pump driven by a traveling engine of a vehicle, and guiding the pressure oil to each actuator by operating a switching valve. Since the hydraulic pump has a fixed displacement, adjusting the operating speed of the hydraulic actuator, such as the loading speed, requires operating the throttle to move the engine speed up and down.

[0003]

SUMMARY OF THE INVENTION In such a case,
When the operation speed of the actuator is increased when the load is light or empty, it is necessary to increase the engine speed and increase the supply flow rate of the pump to the actuator. However, this causes environmental problems such as an increase in noise due to an increase in the engine speed.

When the load is heavy, the engine output is required to increase the engine speed. As a result, the flow rate supplied to the actuator is increased, and the operating speed is increased. If it is desired to lower the operating speed, unnecessary pressure oil must be released by a relief valve or the like, which results in energy loss.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a hydraulic device for a cargo handling vehicle according to the present invention is driven by an internal combustion engine for running a vehicle, and can freely change a discharge amount per unit rotation. A variable hydraulic pressure source to be obtained, one or more actuators driven by a fluid supplied from the variable hydraulic pressure source, operating means for operating the actuator, and rotation speed detection for detecting the rotation speed of the internal combustion engine Means, an operation amount detection means for detecting an operation amount of the operation means, and a discharge amount of the variable hydraulic pressure supply source within a range not exceeding a set discharge amount set as a parameter with the operation amount detected by the operation amount detection means. Discharge amount control means for controlling the discharge amount of the variable hydraulic pressure supply source so as not to further increase when the rotation number detected by the rotation number detection means falls below a predetermined rotation number. Characterized in that it comprises.

[0006]

Therefore, in such a case, when the object to be moved by the actuator is a light load or an empty load, the load applied to the internal combustion engine is small, so that the discharge amount of the variable hydraulic pressure supply source is increased. However, the rotation speed does not fall below the predetermined rotation speed. Therefore, the operating speed of the actuator increases with the increase in the discharge amount. Conversely, if the target object is a heavy load, the load on the internal combustion engine increases with an increase in the discharge amount of the variable hydraulic pressure supply source, and at a certain point, its rotation speed falls below a predetermined rotation speed. The point in time is determined to be the load limit of the internal combustion engine, and the discharge amount of the variable hydraulic pressure supply source is not increased so that no excessive load acts on the internal combustion engine. As a result, the operating speed of the actuator will not increase further. In other words, the operating speed of the internal combustion engine is increased according to the magnitude of the load acting on the actuator without increasing the rotational speed of the internal combustion engine and increasing the noise, or releasing unnecessary pressure fluid and causing energy loss. It will be adjusted automatically. Moreover, the adjustment of the operating speed is
Since the operation is performed within a range that does not exceed the preset discharge amount of the variable hydraulic pressure supply source, the operation amount of the operation means is set as a parameter in advance, if the set discharge amount is set according to the operation amount of the operation lever, Even if the load is light, the operation speed of the actuator can be reduced by the operation amount of the operation lever.

If the rate of increase of the variable hydraulic pressure supply source by the discharge amount control means can be set to a constant speed so as not to increase suddenly, the operating means can be operated rapidly. Also, since the flow rate supplied to the actuator does not suddenly increase, it is possible to prevent the actuator from suddenly operating or transiently causing an overload on the internal combustion engine to cause a stall.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. This embodiment is a hydraulic device applied to, for example, a truck crane 1 as shown in FIGS. First, the truck crane 1 will be briefly described. As shown in FIG. 1, the truck crane 1 is provided with a so-called truck provided with a lifting crane 1A.
The crane 1A includes a boom 11, and the boom 1
The hook 12 is hung from the tip of the hook 1 via a wire 13. And the load is hung on the hook 12,
The load is lifted and moved by the expansion and contraction, turning, and tilting of the boom 11, and the operation of moving the wire 13 forward and backward.

Returning to the main discussion, this hydraulic device is applied to move this crane 1A as shown in FIG. 2, and is a variable pressure device driven by an engine 2, which is an internal combustion engine for running a vehicle. Variable pressure pump 3, which is a hydraulic pressure source,
Actuators 41 to 44 driven by fluid supplied from the variable pump 3, direction switching valves 5 with manual operation levers 51 as operation means provided between the variable pump 3 and these actuators 41 to 44, rotation number detecting means It comprises an engine speed sensor 6 as a barrel, a detection switch 7 as an operation amount detecting means for detecting an operation amount of the operation lever 51, and a controller 2 as a discharge amount control means for increasing and decreasing the discharge amount of the variable pump 3. Note that oil is used as a working fluid in the hydraulic device.

[0010] Explaining each part specifically, the variable pump 3
Is capable of freely changing the discharge amount per rotation, and the discharge amount is controlled by a discharge amount command signal a
Is set in accordance with the voltage of. of course,
As the variable pump 3, various types represented by a swash plate type, an oblique axis type and the like can be used. The actuator directly operates the crane 1A, and in this embodiment, a hydraulic motor 41 for hoist winch for winding the wire 13, a hydraulic motor 42 for turning the boom 11, and a telescopic cylinder 43 for extending and retracting the boom 11 (FIG. 1 is not shown), and a total of four types of derrick cylinders 44 for tilting the boom 11 are provided. Then, the pressure oil discharged from the variable pump 3 is supplied to these four types of actuators 41 to 44 via the direction switching valve 5, respectively.

As shown in FIG. 2, the directional control valve 5 has two input ports P and R and two output ports A and B,
This is a generally known type in which the fluid path between the input ports P, R and the output ports A, B is changed by operating the manual operation lever 51. Specifically, the control lever 51
Closes between the input ports P and R and the output ports A and B in the neutral position. The input port P communicates with the output port A when the operation lever 51 is tilted in one direction, and the input port R communicates with the output port B when the operation lever 51 is tilted in the other direction. P and the output port B, and the input port R and the output port A are communicated with each other.

As shown in FIG. 2, the hydraulic piping of this embodiment has an input port P connected to the output side of the variable pump 3, an input port R connected to the tank 10, and an output port A connected to the corresponding actuator 41. One of the oil outlets and the output port B is connected to the other one of the corresponding actuators 41 to 44, respectively. That is, the hydraulic circuit is configured so that when the operator tilts the operation lever 51 from the neutral position in any direction, the actuators 41 to 44 can operate in a direction corresponding to the tilt direction. In this embodiment, a stack type directional control valve 5 is used, and when the operation levers 51 of all directional control valves 5 are in the neutral position, the output of the variable pump 3 is communicated to the tank 10. In this case, energy loss in this case is prevented. In addition, the output of the variable pump 3 is communicated with the tank 10 via a relief valve to regulate the upper limit of the system pressure and to prevent danger when abnormally high pressure is generated.

The engine speed sensor 6 outputs a frequency or voltage proportional to the engine speed as a speed signal b, and a generally well-known sensor is used. The detection switch 7 detects whether or not the directional control valve 5 has been operated. In the present embodiment, a limit switch is used, which is provided at the end of the operation lever 51 of the directional control valve 5. And whether the operation lever 51 is located at the neutral position or at any other position.
An operation signal c which is an operation amount indicating only a value is output.

The controller 8 includes, for example, a C (not shown).
A generally known device including a PU, a memory, an input interface, an output interface, and the like is used. At least an operation signal c from each detection switch 7 and a rotation speed signal b from the engine speed sensor 6 are input to this input interface. Further, the output interface outputs at least a discharge amount command signal a for commanding the discharge amount of the variable pump 3. Then, the value of the discharge amount command signal a, that is, the variable pump 3
Of each of the signals b and c input to the input interface based on software stored in a memory in advance.
To determine.

An outline of the software will be described below with reference to a flowchart shown in FIG. First, in step S1, a predetermined engine speed is set to, for example, an idling speed (for example, 700 rpm). Next, in step S2, the engine speed signal b is detected, and the value is stored as the engine speed.

In step S3, it is determined whether or not the operation lever 51 is operated based on the operation signal c from each detection switch 7. And operation lever 5
If it is determined that No. 1 has been operated, step S4
If it is determined that the operation has not been performed, the process proceeds to step S9. In step S4, the upper limit of the pump discharge amount, which is the set discharge amount, is set to the maximum discharge amount. Specifically, the maximum value of the discharge amount command signal a is set to a value corresponding to the pump maximum discharge amount. Then, the process proceeds to step S5.

In step S5, the detected engine speed is compared with the idling speed. If the engine speed is equal to or higher than the idling speed, it is determined that an excessive load is not applied to the engine 2, and the process proceeds to step S6. move on. Otherwise, go to step S8. Step S
In 6, it is determined whether the pump discharge amount is lower than the upper limit amount set in step S4. If it is below, the process proceeds to step S7, and if not, the process proceeds to step S8.

In step S7, the pump discharge amount is increased at a constant speed, and the process returns to step S1. In step S8, the pump discharge amount is not changed, and step S8 is performed.
Return to 1. In step S9, the pump discharge amount is set to the minimum discharge amount 0. This includes setting the upper limit of the pump discharge amount to the minimum discharge amount 0. Then, the process returns to step S1.

This series of operations is repeated as one control cycle. In this embodiment having the above-described configuration, an operation when the operator operates the turning motor 42, for example, will be described with reference to FIG. First, when the operator does not operate the operation lever 51, the operation lever 51 is not operated.
Is in the neutral position, the state of which is detected by the detection switch 7 (step S3), and the pump discharge amount becomes the minimum value 0 (step S9).

Next, when the operator tilts the operation lever 51 in any direction and operates, for example, an empty load or a very light load, the operation of the operation lever 51 is detected by the detection switch 7. (Step S3). At first, the pump discharge amount is the minimum discharge amount 0 and no load is applied to the engine 2, so that the engine speed is maintained at the idle speed. Therefore, according to the determinations in steps S5 and S6, the pump discharge amount increases at a constant speed (step S5).
7). Thus, even if the load is light and the pump discharge amount increases, almost no load is applied to the engine 2. Therefore, the pump discharge amount increases to the maximum discharge amount set in step S4 while the engine rotational speed remains idle. The state is maintained. The time change of the pump discharge amount described above is shown in FIG. That is, when an empty load or a very light load is operated, the discharge amount of the variable pump 3 increases to the maximum discharge amount while the engine speed remains idle and the turning motor 4
2 will be driven at maximum speed.

When a heavy load is operated, immediately after the operation of the operation lever 51 is detected by the detection switch 7 (step S3), the pump discharge amount is the minimum value and the load on the engine 2 is increased as described above. The engine speed is maintained at the idling speed because it does not start. Therefore, according to the determinations in steps S5 and S6, the pump discharge amount increases at a constant speed (step S7). Then
Since the load acting on the engine 2 increases with an increase in the pump discharge amount, and the engine rotational speed falls below the idle rotational speed, the pump discharge amount is fixed when the engine rotational speed falls below the idle rotational speed (step S8). As a result, the pump discharge rate is
The balance is achieved at a point where the engine speed is slightly lower than the idle speed, so that an excessive load is prevented from being applied to the engine 2. The time variation of the pump discharge amount described above is shown in FIG. That is, if the load is heavy, the discharge amount of the variable pump 3 is determined so that the load applied to the engine 2 is not excessive, and the operating speed of the turning motor 42 becomes correspondingly small. In the present embodiment, the pump discharge amount is not changed in step S8. However, the same operation as described above can be obtained even if the pump discharge amount is reduced.

That is, according to the present embodiment, the operating speed is adjusted according to the magnitude of the load acting on the actuators 41 to 44. Therefore, with such a simple control, it is possible to prevent the output energy of the engine 2 from being lost due to an unnecessary increase in the engine speed and an increase in noise, or an unnecessary release of pressure oil. Further, as described in step 7, the discharge amount increasing speed of the variable pump 3 (the gradient of the first half of the graphs G and H shown in FIG. 4).
Is set appropriately in software. Therefore,
Even if the operation lever 51 is suddenly operated, the actuator 4
It is possible to prevent a sudden increase in the flow rate supplied to the actuators 1 to 44, and it is possible to prevent the actuators 41 to 44 from suddenly operating or from transiently applying an excessive load to the engine 2 and causing engine stall.

Further, according to this embodiment, since the detection switch 7 is provided at the end of the operation lever 51, it can be easily retrofitted to the existing directional control valve 5. Including this, the conventional fixed pump can be replaced with the variable pump 3 according to the present embodiment, and the existing hydraulic piping and the arrangement of parts can be significantly changed only by performing simple electric wiring including the controller 8 and the like. It can be easily and inexpensively replaced with this device. Therefore, the present embodiment can be applied to a small or medium-sized work vehicle that requires a particularly low cost.

It should be noted that the present invention is not limited to the above-described embodiment, but can be variously modified. For example, in the above-described embodiment, the detection switch 7 is used to detect the operation amount of the operation lever 51, and the lever operation amount indicates only two values (the neutral position or not). Is set to the minimum discharge amount 0, and if not, the set discharge amount is set to the maximum discharge amount. Thus, a detector (for example, a potentiometer) capable of detecting the stroke of the operating lever is provided instead of the detection switch 7, and the set discharge amount of the variable pump is set in proportion to the operation amount detected by the detector, that is, the stroke amount. I will decide. By controlling the discharge amount of the variable pump within a range not exceeding the set discharge amount and controlling the load acting on the engine, even if the load is light, the operation speed of the actuator can be reduced by the operation amount. become able to.

Further, in this embodiment, the operation speed of the actuator can be increased / decreased also by the throttle operation as in the related art. In this case, for example, if a throttle detector for detecting an operation amount of a throttle lever (not shown) is provided, and a predetermined engine speed is set according to the detected throttle opening, the engine can be further improved. It can be used efficiently.

Further, the type and number of the hydraulic actuators are not limited to those of the present embodiment, and the hydraulic components such as the direction switching valve and the controller are not limited to those of the embodiment. For example, the direction switching valve may be of an electromagnetic drive type. Of course, it goes without saying that the present invention is applicable not only to truck cranes but also to various work engine vehicles.

In addition, the configuration of each section is not limited to the illustrated example, and various modifications can be made without departing from the spirit of the present invention.

[0028]

The present invention is embodied in the form described above and has the following effects. The present invention provides a hydraulic pressure source which is a variable hydraulic pressure supply source capable of freely changing a discharge amount per unit rotation, an operation amount detection means for detecting an operation amount of an operation means for operating an actuator, and a rotation of an internal combustion engine. A rotational speed detecting means for detecting the number of rotations, and a discharge amount control means for controlling the discharge amount of the variable hydraulic pressure supply source. The discharge amount control means controls the variable hydraulic pressure supply source in which the operation amount is set as a parameter. The discharge amount of the variable hydraulic pressure supply source is increased within a range not exceeding the set discharge amount, and the discharge amount of the variable hydraulic pressure supply source is further increased when the rotation speed detected by the rotation speed detection means falls below a predetermined rotation speed. This is a hydraulic device that controls so as not to increase. Therefore, with such a simple control, it is possible to increase the operation speed of the actuator without increasing the rotation speed of the internal combustion engine,
Noise can be reduced. Further, even when a high load acts on the actuator, by reducing the discharge amount, the load acting on the internal combustion engine can be suppressed, and energy loss can be reduced. In addition, the adjustment of the operating speed is performed within a range that does not exceed the set discharge amount of the variable hydraulic pressure source set in advance by using the operation amount of the operation means as a parameter. If the setting is made, the operation speed of the actuator can be reduced by the operation amount.

[Brief description of the drawings]

FIG. 1 is an overall view showing a first embodiment of the present invention.

FIG. 2 is a circuit diagram of a hydraulic device in the embodiment.

FIG. 3 is a control flowchart of a controller in the embodiment.

FIG. 4 is a graph showing a change over time of the discharge amount of the variable pump in the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Vehicle (truck crane) 2 ... Internal combustion engine (engine) 3 ... Variable hydraulic pressure supply source (variable pump) 41-44 ... Actuator 5 ... Operating means (directional switching valve) 6 ··· Rotation speed detection means (engine speed sensor) 7 ··· Operation amount detection means (detection switch) 8 ··· Discharge amount control means (controller)

Claims (1)

[Claims] 1. A variable hydraulic pressure source which is driven by an internal combustion engine for running a vehicle and which can freely change a discharge amount per unit rotation thereof, and a variable hydraulic pressure source which is driven by a fluid supplied from the variable hydraulic pressure source. A plurality of actuators, operating means for operating the actuators, rotational speed detecting means for detecting the rotational speed of the internal combustion engine, operating amount detecting means for detecting the operating amount of the operating means, and detecting by the operating amount detecting means The discharge amount of the variable hydraulic pressure supply source is increased within a range that does not exceed the set discharge amount set as a parameter with the manipulated amount set as a parameter, and when the rotation speed detected by the rotation speed detection means falls below a predetermined rotation speed, the variable hydraulic pressure is reduced. A hydraulic device for a cargo handling vehicle, comprising: a discharge amount control means for controlling a discharge amount of a supply source so as not to further increase.