JP2004340259A - Drive system for travelling of construction machinery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure smooth turn operation by preventing sudden drop of turn speed. <P>SOLUTION: When load pressure of variable displacement hydraulic motors 7 and 8 as a drive source of right and left travelling bodies is beyond a setting value, motor capacity is enlarged. On condition that a drive system is automatically set to switch from a second-speed mode with small torque at high speed to a first-speed mode with large torque at low speed, the speed mode is forcibly switched to the first-speed mode when spin turn operation is performed by the second-speed mode. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a traveling drive device for a construction machine having a crawler traveling body such as a hydraulic shovel.
[0002]
[Prior art]
This type of travel drive device uses a hydraulic motor as a drive source, and switches the capacity of the motor between a large torque and low speed 1 speed mode and a small torque and high speed 2 speed mode. Normally, the first speed mode is set when the running load is large such as when starting or climbing a hill, and the second speed mode is set when the running load is small and the high speed running is required such as on a flat ground. .
[0003]
Conventionally, as a technique relating to the switching of the traveling mode, an automatic switching method for automatically switching to a first speed mode when a load pressure (operating pressure) of a hydraulic motor exceeds a set value during traveling in a second speed mode ( For example, see Patent Document 1).
[0004]
[Patent Document 1]
JP-A-5-156666 [0005]
[Problems to be solved by the invention]
However, according to the above-mentioned known technique, in a large-sized machine having a large own weight and a large load pressure during traveling, a spin-turn operation for turning the two hydraulic motors in opposite directions during the second speed traveling is performed. At the time, the following trouble occurred.
[0006]
That is, if the load pressure of both hydraulic motors sufficiently exceeds the set value by the spin turn operation, the mode is automatically switched to the first speed mode, but there is no problem. However, the load pressure rises to near the set value, or the load pressure increases over the set value. If it fluctuates, the pump flow rate is reduced by the PQ characteristic (pressure × flow rate = constant horsepower characteristic where the pressure is equal to the flow rate) of the pump which is the hydraulic pressure source in the second speed mode with a small torque. Significantly (below the spin turn in the first speed mode).
[0007]
In such a case, the spin turn is slowed down, and the movement is contrary to the operator's will. As a result, the operability is deteriorated, and the evaluation of the performance of the machine is reduced.
[0008]
As a technique related to this, in Patent Document 1 described above, during the second speed running, at the time of a pivot turn in which one hydraulic motor is stopped and the direction is changed only by the other hydraulic motor, the capacity of the stopped hydraulic motor is increased. There is disclosed a technique for enhancing braking force.
[0009]
However, in this known technique, the drive-side hydraulic motor remains in the second-speed mode (small torque), so that it is impossible to prevent the sudden decrease in the turn speed due to the decrease in the pump flow rate.
[0010]
Therefore, the present invention provides a traveling drive device for a construction machine capable of preventing a sharp drop in the turn speed and performing a smooth turn operation.
[0011]
[Means for Solving the Problems]
According to the first aspect of the present invention, the left and right traveling bodies, the hydraulic motors for separately driving the two traveling bodies, the operation means for commanding the operation of the two hydraulic motors, and the load pressure for detecting the load pressure of the two hydraulic motors are provided. Detecting means, turn operation detecting means for detecting that a turn operation such as a spin turn has been performed, mode switching means for switching a traveling mode between a plurality of traveling modes having different torques, and a mode for the mode switching means. Control means for sending a switching signal, wherein the control means, when in a predetermined small torque running mode, when the load pressure detected by the load pressure detecting means becomes equal to or higher than a set value, and when the turn operation is performed. When a turn operation is detected by the detection means, the driving mode is switched to a predetermined large torque running mode.
[0012]
According to a second aspect of the present invention, in the configuration of the first aspect, a mode instructing means is provided which is operated by an operator to instruct a running mode of a predetermined small torque to the control means, and the control means detects a turn operation. Sometimes, the driving mode is switched to a predetermined large torque driving mode regardless of the mode instruction by the mode instruction means.
[0013]
According to a third aspect of the present invention, in the configuration of the first or second aspect, the mode switching means changes the capacity of the hydraulic motor to switch the traveling mode between the large torque first speed mode and the small torque second speed mode. The control means switches the running mode to the first speed mode when the load pressure becomes equal to or higher than a set value during the running in the second speed mode and when the turn operation is performed. It is comprised in.
[0014]
According to a fourth aspect of the present invention, in the configuration of any one of the first to third aspects, the turn operation detecting means detects that a spin turn operation in which the rotation directions of both hydraulic motors are opposite to each other is performed. It was done.
[0015]
According to the above configuration, when the load pressure is equal to or higher than the set value and the turn operation such as the spin turn is performed during the traveling in the traveling mode with the predetermined small torque (the second speed mode in claim 3). Then, both hydraulic motors are automatically switched to the large torque running mode (the first speed mode) by the operation of the control means.
[0016]
Therefore, for example, even when the load pressure rises to near the set value or fluctuates over the set value during the spin turn operation of claim 4, the hydraulic motor runs at a predetermined large torque when the spin turn operation is performed. The mode is switched to a mode, whereby the load pressure is reduced and the pump flow rate is restored, so that a sharp drop in speed as in the conventional case does not occur. Therefore, the operability of the turn operation is improved.
[0017]
Further, according to the second aspect of the present invention, when the mode is provided with the mode instructing means and the mode is switched to the low-torque running mode by the operator's intention, even if the low-torque running mode is instructed, it is compulsory during the turn operation. Since the driving mode is set to a large torque, a favorable turn operability can be ensured.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to the drawings.
[0019]
FIG. 3 shows a hydraulic shovel on which the traveling drive device according to the embodiment is mounted.
[0020]
In FIG. 1, reference numeral 1 denotes a crawler-type traveling device on which an upper revolving unit 2 is mounted so as to be pivotable about a vertical axis, and the upper revolving unit 2 is provided with a boom 3, an arm 4 and a bucket 5. The work attachment 6 is attached.
[0021]
In the traveling device 1 of the hydraulic shovel, the left and right traveling bodies (only one side is shown here) 1a are separately driven by variable displacement traveling hydraulic motors, and the capacity of the motors is switched between large and small. As a result, the traveling mode is switched between a first speed mode with a large torque and a low speed and a second speed mode with a small torque and a high speed.
[0022]
FIG. 1 shows the configuration of a traveling drive device having this mode switching function.
[0023]
In FIG. 1, reference numerals 7 and 8 denote variable displacement hydraulic motors for right and left traveling bodies, and reference numeral 9 denotes a hydraulic pump serving as a hydraulic source for both hydraulic motors 7 and 8. , 8 are provided with hydraulic pilot control valves 10 and 11 for left traveling and right traveling, respectively.
[0024]
The control valves 10 and 11 are switched by left and right remote control valves 12 and 13 as operating means, respectively. The switching operation of the control valves 10 and 11 causes the hydraulic motors 7 and 8 to operate. The rotation direction (shovel running direction) and speed are controlled. T is a tank.
[0025]
The mode switching means in the traveling drive device includes capacity switching cylinders 14 and 15 for switching the capacity of the two hydraulic motors 7 and 8 in two ways, large and small, and an electromagnetic capacity switching for controlling the operation of the two capacity switching cylinders 14 and 15. The capacity switching valve 16 is controlled by a controller 17 as control means.
[0026]
The capacity switching valve 16 has a tank position a communicating with the tank T and a pressure supply position b for supplying the hydraulic pressure from the auxiliary hydraulic source 18 to the capacity switching cylinders 14 and 15, and is controlled by a control signal from the controller 17. When the switching valve 16 switches from the illustrated tank position a to the pressure supply position b, the two-capacity switching cylinders 14 and 15 are extended to switch the two hydraulic motors 7 and 8 to the small-capacity (second speed mode). .
[0027]
On the other hand, as a detecting means, a load pressure sensor 19 for detecting a load pressure, and a turn operation sensor for detecting that a spin turn operation has been performed by the left and right forward and reverse pilot pressures output from the traveling remote control valves 12 and 13. 20 to 23 are provided, and signals from these sensors 19 to 23 are input to the controller 17.
[0028]
The controller 17 receives a signal from a second speed instruction switch 24 that is manually operated by an operator and instructs a second speed mode. When the second speed instruction signal is input, the controller 17 supplies an exciting current to the capacity switching valve 16. Is sent to extend the capacity switching cylinder 14, and both hydraulic motors 7, 8 are set to the second speed mode.
[0029]
The operation of this apparatus including the control contents of the controller 17 will be described with reference to the flowchart of FIG.
[0030]
After the start of the control, it is determined in step S1 whether or not a second speed command is issued by the second speed command switch 24. If NO, normal control is performed in step S2, that is, the capacity switching valve 16 is set to the tank position a. Then, both the hydraulic motors 7 and 8 are set to the first speed mode, and control for running at a large torque and a low speed is performed, and then the process returns to the step S1.
[0031]
On the other hand, in the case of YES (a second speed instruction has been issued), the flow shifts to step S3, where an exciting current is sent from the controller 17 to the capacity switching valve 16, and the switching valve 16 is switched to the pressure supply position b. , Both hydraulic motors 7 and 8 are switched to the second speed mode.
[0032]
Then, in the second speed mode, it is determined in step S4 whether a spin turn operation has been performed based on a signal from the turn operation sensors 20 to 23 (a signal of left forward + right reverse or a right forward + left reverse). Is determined.
[0033]
Here, when the spin turn operation is not performed, the normal control is performed in step S5, that is, when the load pressure detected by the load pressure sensor 19 is less than the set value, the second speed mode is maintained. After the control for automatically switching the two hydraulic motors 7 and 8 to the first speed mode is performed, the process returns to step S1.
[0034]
Accordingly, high-speed traveling is possible in a situation where the traveling load is small such as a flat road, and a large torque is produced in a situation where the traveling load is high, so that starting and climbing traveling can be performed smoothly.
[0035]
On the other hand, if the answer is YES in step S4 in the second speed mode, that is, if the spin turn operation is performed, regardless of the second speed mode instruction and the value of the load pressure, both hydraulic motors 7, 8 are set to 1 in step S6. The mode is forcibly switched to the speed mode.
[0036]
By switching to the first speed mode, a rise in load pressure is suppressed, and a pump flow rate in the first speed mode is secured based on the PQ characteristics. As described above, the phenomenon that the pump flow rate is reduced by increasing the load pressure to near the set value or fluctuating over the set value does not occur, and the speed is reduced to the first speed or less.
[0037]
Therefore, a smooth spin-turn operation that does not go against the intention of the operator can be ensured, and the operability of the spin-turn operation is improved.
[0038]
After step S6, the process returns to step S1, and thereafter, the traveling operation in the first speed mode is performed unless the second speed instruction is given again by the mode instruction switch 24.
[0039]
Other Embodiments (1) In the above embodiment, the second speed mode is set when the second speed instruction switch 24 is operated, and the first speed mode is set otherwise. A configuration in which the first speed and the second speed are manually switched by a switch may be employed.
[0040]
Also in this case, a configuration may be adopted in which the mode is switched to the first-speed mode when the load pressure becomes equal to or higher than the set value while the second-speed mode is selected and when the spin turn operation is performed.
[0041]
Alternatively, assuming that there is no second-speed instruction switch or changeover switch as described above, and the first-speed / second-speed switching is automatically performed based only on the load pressure, the second-speed mode is set when the load pressure is equal to or less than the set value. It may be configured to switch to the first speed mode when the spin turn operation is performed in the state of being turned on.
[0042]
(2) In the above embodiment, when the spin turn operation is performed, the mode is switched to the first speed mode. However, the pivot turn operation in which one hydraulic motor is stopped and only the other hydraulic motor is rotated to change the direction is performed. May be configured to switch to the first speed mode even when is performed.
[0043]
(3) In the above embodiment, the turn operation is detected by the pilot pressure of the remote control valves 12 and 13, but the mechanical movement of the remote control valves 12 and 13 during the turn operation may be detected by a limit switch or the like. Good.
[0044]
Alternatively, in a machine that controls an electromagnetic pilot-type control valve by operating an electric joystick, a configuration that detects an electric signal (for example, voltage) from the electric joystick can be employed as the turn operation detecting means.
[0045]
(4) In the above-described embodiment, the drive mode is switched between the first speed and the second speed by switching the capacity of the hydraulic motors 7 and 8 between large and small. May be taken.
[0046]
(5) In the above embodiment, the driving mode is switched between the first speed and the second speed. However, the driving mode may be switched between the first speed, the second speed, the third speed, and higher modes.
[0047]
In this case, when a turn operation is performed during traveling in a mode other than the first speed mode, all the modes may be switched to the first speed mode, or a mode immediately below the mode when the turn operation is performed. (For example, the second speed mode under the third speed mode).
[0048]
【The invention's effect】
As described above, according to the present invention, when the vehicle is traveling in a traveling mode with a predetermined small torque (second speed mode in claim 3), when the load pressure exceeds a set value, and when a turn operation such as a spin turn is performed. When the vehicle is turned, the two hydraulic motors are automatically switched to a predetermined large torque running mode (the first speed mode) by the operation of the control means. During operation), the pump pressure can be secured by suppressing an increase in load pressure, and a sudden drop in speed can be prevented.
[0049]
Therefore, a smooth turn operation that does not go against the intention of the operator can be secured, and the operability of the turn operation can be improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing an overall configuration of a traveling drive device according to an embodiment of the present invention.
FIG. 2 is a flowchart for explaining the operation of the apparatus.
FIG. 3 is a schematic side view of a hydraulic excavator to which the present invention is applied.
[Explanation of symbols]
1a Traveling body 7, 8 Traveling hydraulic motor 9 Hydraulic pump 10, 11 Control valve 12, 13 Traveling remote control valve 14, 15 as operating means Capacity switching cylinder 16 constituting mode switching means 16 Capacity switching valve 17 Control means Controller 19 as load pressure sensors 20 to 23 as load pressure detection means Turn operation sensor 24 as turn operation detection means 24 Mode instruction switch as mode instruction means

Claims (4)

Right and left traveling bodies, hydraulic motors for separately driving the two traveling bodies, operating means for commanding the operation of the two hydraulic motors, load pressure detecting means for detecting the load pressure of the two hydraulic motors, spin turn, etc. Turn operation detecting means for detecting that a turn operation has been performed, mode switching means for switching a traveling mode between a plurality of traveling modes having different torques, and control means for sending a mode switching signal to the mode switching means. Wherein the control means detects a turn operation by the turn operation detection means when the load pressure detected by the load pressure detection means becomes equal to or more than a set value in a predetermined small torque traveling mode. A traveling drive device for a construction machine, wherein each of the traveling modes is switched to a predetermined large torque traveling mode. Mode instruction means is provided which is operated by an operator and instructs the control means in a traveling mode of a predetermined small torque. When the turn operation is detected, the control means operates in the traveling mode regardless of the mode instruction by the mode instruction means. The driving device for a construction machine according to claim 1, wherein the driving mode is switched to a predetermined large torque driving mode. 3. The traveling drive device for a construction machine according to claim 1, wherein the mode switching means switches the traveling mode between a first speed mode with a large torque and a second speed mode with a small torque by changing the capacity of the hydraulic motor. The control means is configured to switch the traveling mode to the first-speed mode when the load pressure becomes equal to or higher than a set value during traveling in the second-speed mode and when the turn operation is performed. A traveling drive device for a construction machine, comprising: The turn operation detecting means is configured to detect that a spin turn operation in which the rotation directions of both hydraulic motors are opposite to each other is performed, the turn operation detection means being configured to detect the spin operation. Driving equipment for construction machinery.

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