JP2012122555A - Control method of traveling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control method of a traveling device that can perform delicate control corresponding to a load in a low speed zone and can perform control close to a speed control independent on a load of a travelling system in a high speed zone.SOLUTION: The control method of a traveling device equipped with a driving source, a fluid pressure pump of variable-capacity type driven by the driving source, and a fluid pressure motor of variable-capacity type connected to an axis of the traveling device, and constructed so that the pump and the motor form a closed circuit, is characterized by controlling a horsepower (W(Nm)) of the traveling device to a revolution (Nm) of the motor according to a function represented by W(Nm)=α×Ne×Nm×(XO-Nm), (wherein Ne indicates a revolution of the motor; α and XO indicate a positive constant; and n indicates an integer of 1 or more).

Description

  The present invention relates to a traveling device control method, and more particularly, a traveling device control method including a hydraulic circuit configured to form a closed circuit by a variable displacement fluid pressure pump and a variable displacement fluid pressure motor. About.

Conventionally, a hydrostatic pump in which a variable capacity fluid pressure pump driven by a driving source such as an engine and a variable capacity fluid pressure motor connected to an axle and rotating a tire or the like are connected in a closed circuit. A traveling device for a transmission is disclosed in Patent Document 1, for example.
In the case of this type of traveling device, the rotational speed of the drive source is determined based on a command from an accelerator pedal or the like, and the fluid pressure pump is driven at this rotational speed. Since the fluid pressure pump and the fluid pressure motor form a closed circuit, the fluid pressure motor is substantially driven at a speed proportional to the rotational speed, and the vehicle speed is also proportional to the rotational speed. As a result, the conventional traveling device travels with a horsepower characteristic proportional to the vehicle speed.
However, in the case of a horsepower characteristic proportional to the vehicle speed as in a conventional traveling device, the output horsepower from the start of running to the low speed range is insufficient, and an excessive output horsepower is generated in the high speed range. There was a problem that the ring was bad and the energy from the drive source could not be used effectively.

JP 2006-240324 A (FIG. 2)

  Therefore, the present invention provides a control method for a traveling device that enables subtle control according to the load in the low speed range and enables control close to speed control independently of the load of the traveling system in the high speed range. With the goal.

In order to solve the above problems, the inventors have found a solution as follows.
That is, the control method of the traveling device of the present invention includes a drive source, a variable displacement fluid pressure pump driven by the drive source, and a variable displacement fluid connected to an axle. A traveling device control method comprising a pressure motor, wherein the pump and the motor are configured as a closed circuit, wherein the horsepower of the traveling device (with respect to the rotational speed (Nm) of the motor ( W (Nm))
W (Nm) = α ・ Ne ・ Nm ・ (X0-Nm) ⁿ
(In the formula, Ne is the rotation speed of the pump, α and X0 are positive constants, and n is an integer of 1 or more.)
It controls according to the function represented by these.
According to a second aspect of the present invention, in the first aspect of the present invention, the rotational speed (Ne) of the pump is converted into a pressure control value of the pump to detect the pressure in the closed circuit. However, the pressure control value is adjusted.

  As described above, according to the present invention, force control is performed when the traveling device is started up, and in the intermediate speed range, horsepower control is performed when the speed is relatively low, and load is applied when the speed is relatively high. Independently, speed control for keeping the speed constant can be mainly controlled.

Explanatory drawing of the function of the horsepower characteristic of one embodiment of the present invention Explanatory drawing of the traveling device of the embodiment

Next, an embodiment of the present invention will be described with reference to the drawings.
In FIG. 1, a variable displacement fluid pressure pump 1 and a variable displacement fluid pressure motor 2 are connected through flow paths 3 and 4 so as to form a closed circuit. The variable displacement fluid pressure pump 1 and the motor 2 are not particularly limited as long as their capacities can be changed. For example, an oblique shaft type or a swash plate type should be used. Can do. In the following description, the variable displacement fluid pressure pump 1 and the motor 2 will be described using a swash plate pump and a motor.
The pump 1 is driven by a drive source 6 such as an engine via a drive shaft 5. The drive source 6 is controlled by a member 7 for setting the rotational speed of an accelerator pedal, a lever, or the like. The drive shaft 5 connecting the drive source 6 and the pump 1 is provided with a sensor 8 for detecting the rotational speed Ne of the motor. In addition, sensors 9 and 10 for pressure detection are provided in the flow paths 3 and 4, respectively. Signals from these sensors 9 and 10 are sent to a pump control device 11 for controlling the tilt angle of the pump 1.
The motor 2 is connected to a traveling system such as wheels via a drive shaft 12. Note that the traveling system includes a clutch or the like as necessary. The drive shaft 12 is provided with a sensor 13 for detecting the rotational speed Nm of the motor 2. A signal from the sensor 13 is sent to a motor control device 14 for controlling the tilt angle of the motor 2.

The pump control device 11 controls the pump 1 using a value obtained by multiplying the rotation speed Ne of the pump 1 by a constant α as a discharge pressure command value. In the present embodiment, the tilt amount of the pump 1 is controlled. Note that the pump control device 11, based on the discharge pressure command value, discharges to the flow path 3 side, and discharges the flow path 3 side pressure to the flow path 4 side. The pressure is acquired by the sensors 9 and 10 and is controlled to the intended pressure by performing closed loop control.
The constant α is not particularly limited as long as it is a positive constant.

The motor control device 14 controls the motor 2 using a value obtained by multiplying the rotation speed Nm of the motor 2 by (X0−Nm) ⁿ as an absorption amount command value of the motor 2. In the present embodiment, the amount of tilt of the motor 2 is controlled.
X0 is a positive constant and n is not particularly limited as long as it is an integer of 1 or more. In this embodiment, Nm · (q _max −β · Nm) ⁿ is used as Nm · (X0−Nm) ⁿ . Here, q _max is the maximum absorption amount of the motor 2, and β is a constant of 0 or more. q _max −β · Nm is preferably 15% or less of q _max .

By performing the above control, the horsepower (W (Nm)) of the traveling device is an upwardly convex curve as shown in FIG. 1, and the intersection point with the Nm axis (axis proportional to the speed of the motor 2) is X0.
By controlling the horsepower so that it becomes such a function, when the traveling device is started, the force control is mainly controlled, and the horsepower control is performed on the lower side of the intermediate range of the speed (the rotational speed Nm of the motor 2). Thus, on the higher side of the intermediate range, it becomes possible to control with characteristics close to speed control independent of the load of the motor 2.

DESCRIPTION OF SYMBOLS 1 Fluid pressure pump 2 Fluid pressure motor 3 Flow path 4 Flow path 5 Drive shaft 6 Drive source 7 Member for setting rotation speed 8 Rotation speed detection sensor 9 Pressure detection sensor 10 Pressure detection sensor 11 Pump control device 12 Drive shaft 13 Rotational speed detection sensor 14 Motor controller

Claims (2)

A drive source, a variable displacement fluid pressure pump driven by the drive source, and a variable displacement fluid pressure motor connected to an axle, the pump and the motor being in a closed circuit A method of controlling a configured traveling device,
The horsepower (W (Nm)) of the traveling device with respect to the rotational speed (Nm) of the motor,
W (Nm) = α ・ Ne ・ Nm ・ (X0-Nm) ⁿ
(In the formula, Ne is the rotation speed of the pump, α and X0 are positive constants, and n is an integer of 1 or more.)
Control method according to the function represented by the following.   The rotation speed (Ne) of the pump is converted into a pressure control value of the pump, and adjusted to be the pressure control value while detecting the pressure in the closed circuit. The control method of the traveling apparatus as described.

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