JPH06137308A - Oil pressure estimating device - Google Patents

Abstract

PURPOSE:To provide a pressure estimating device capable of linearly detecting oil pressure in a hydraulic circuit with inexpensive constitution without using an expensive pressure sensor. CONSTITUTION:A controller 17 receives a signal (a) from a pressure switch 9, and judges that the oil pressure at the time is the operation threshold of the pressure switch 9 at the time when the state of the pressure switch 9 is changed. Thereafter, the controller 17 calculates oil consumption in actuators 13, 15 on the basis of signals (d), (g), (h) showing stroke qualities of the actuators 13, 15, and calculates the change quantity of oil pressure from the oil consumption according to the known oil consumption-oil pressure characteristic possessed by an accumulator 7. The present oil pressure is estimated from the oil pressure change quantity and the operation threshold of the pressure switch 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic pressure estimating device for estimating hydraulic pressure in a hydraulic circuit having an accumulator.

[0002]

2. Description of the Related Art In a conventional hydraulic circuit having an accumulator, it is constantly monitored whether or not the hydraulic pressure is within an appropriate pressure range, and if the hydraulic pressure exceeds the appropriate range, the hydraulic pump is stopped, and The on / off control of the hydraulic pump is performed so that the hydraulic pump is operated if the value is below the range.

For this control, a pressure switch is used as a means for detecting whether or not the hydraulic pressure is within an appropriate range. As shown in FIG. 2, this pressure switch operates so as to turn off when the hydraulic pressure exceeds a predetermined upper threshold value and turn off when the hydraulic pressure falls below a predetermined lower threshold value.

[0004]

As described above, in the conventional hydraulic circuit, only the binary judgment is made by using the hydraulic switch whether or not the hydraulic pressure exceeds the predetermined threshold value. . This is because it is a binary control whether the control for the hydraulic pump is on or off. However, needless to say, if it is possible to perform a linear hydraulic pressure detection that can determine what the hydraulic pressure is, it is possible to provide finer control for various operating elements related to the hydraulic circuit including the hydraulic pump. Yes.

A pressure sensor has been conventionally known as a means for performing such linear pressure detection. However, this pressure sensor has a problem that the cost is high.

Therefore, it is an object of the present invention to provide a pressure estimating device capable of linearly detecting the hydraulic pressure in a hydraulic circuit with an inexpensive structure without using a costly pressure sensor.

[0007]

In order to achieve the above object, the present invention provides a pressure switch which is turned on / off with a predetermined hysteresis characteristic with respect to an oil pressure supplied to a load, and a pressure switch which is supplied to the load. A device for estimating the hydraulic pressure in a hydraulic circuit that has an accumulator that stores hydraulic oil and generates a hydraulic pressure according to the amount of the oil, and consumes the oil due to the load after the on / off state of the pressure switch is switched. From the means for measuring the quantity and the measured oil consumption, according to the known oil consumption-hydraulic characteristics of the accumulator,
Means for calculating the amount of change in hydraulic pressure and turning on / off of the pressure switch
It is characterized in that it is provided with means for calculating a hydraulic pressure from a predetermined threshold value for switching the off state and the calculated hydraulic pressure change amount.

[0008]

The pressure switch is turned on / off depending on whether the hydraulic pressure is above the upper threshold value or below the lower threshold value. Therefore, when the on / off state of the pressure switch is switched, it can be seen that the hydraulic pressure is at the upper threshold value or the lower threshold value. The device of the present invention measures the oil consumption amount due to the load from the time when the hydraulic pressure reaches the upper or lower threshold value. Then, according to the known oil consumption-hydraulic pressure characteristic of the accumulator, a hydraulic pressure change amount corresponding to the measured oil consumption amount is calculated, and the present hydraulic pressure is calculated from this hydraulic pressure change amount and the above-mentioned upper or lower threshold value. Is estimated.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a hardware configuration of an embodiment of a hydraulic pressure estimating device according to the present invention. This embodiment is suitable for a hydraulic circuit for driving a vehicle clutch, shift and select.

In FIG. 1, the hydraulic pressure generator 1 has a hydraulic pump 3, a motor 5 for driving the hydraulic pump 3, an accumulator 7 for storing oil under pressure, and a hydraulic switch 9 for opening and closing according to the hydraulic pressure.

The hydraulic pressure generator 1 sucks up oil from the oil tank 11, applies pressure to the oil, and supplies it to the clutch actuator 13 and the shift / select actuator 15. A controller 17 is provided to control the operation of this hydraulic circuit. Controller 17
Includes a microcomputer, and as input signals, the pressure switch signal a from the pressure switch 9, the clutch sensor signal d from the clutch sensor 19 that detects the stroke amount of the clutch actuator 13, and the select sensor 21 that detects the stroke amount of the select actuator. From the shift sensor 23 for detecting the stroke amount of the shift actuator. In addition, this controller 17
Is a drive signal b for turning on / off the motor 5, a clutch drive signal c for driving the clutch actuator 13, a select drive signal f for driving the select actuator, and a shift actuator as output signals. A shift drive signal g for generating

The pressure switch signal a input from the pressure switch 9 to the controller 17 indicates the state of the pressure switch 9, which has the characteristic shown in FIG. That is, when the oil pressure falls below the lower threshold value P1, the switch 9 closes, and when it exceeds the upper threshold value P2, the switch 9 opens.
Then, the controller 17 turns on / off the motor 5 in response to the open / closed state of the pressure switch 9. As a result, the pressure of the oil supplied from the hydraulic pressure generator 1 is kept within the range between the threshold values P1 and P2.

The accumulator 7, as shown in FIG.
The oil 25 is stored therein, and the pressure of the filling gas 27 is applied to the stored oil. And the actuator 1
The amount of oil stored in the accumulator 7 increases or decreases in accordance with the amount of oil consumption at 3 and 15, and the hydraulic pressure applied from the filling gas changes. Its characteristics are determined by the filling gas pressure of the accumulator 7 and the capacity of the container, as shown in FIG. The hydraulic pressure actually used is in the range between the pressures P1 and P2, and the characteristic curve in this range is approximated to a straight line having a slope α1 and there is no practical problem.

In this embodiment according to the present invention, the characteristic of FIG. 4 is utilized to estimate the oil pressure during motor stop from the oil consumption amount. In this case, the oil consumption is
It can be easily calculated from the stroke amount of 15 according to the following formula.

Oil consumption = Actuator stroke amount × K [Equation 1] where K is the cylinder cross-sectional area of the actuator.

Therefore, the hydraulic pressure when the motor is stopped can be roughly calculated from the following equation.

Hydraulic pressure = P2-oil consumption / α1 [Equation 2] On the other hand, when the motor is driven, the hydraulic pump 3 acts to increase the hydraulic pressure in proportion to its operating time, as shown in FIG. go. The slope α2 of this increase is determined by the rotation speed of the motor 5, the performance of the pump 3, and the characteristics of the accumulator 7. Therefore, the hydraulic pressure during the motor drive can be roughly calculated from the following equation in consideration of the hydraulic pressure increase amount by the hydraulic pump 3 and the decrease amount of the accumulated hydraulic pressure in the accumulator 7 according to the oil consumption amount.

Hydraulic pressure = P1 + motor drive time × α2−oil consumption / α1 [Equation 3] The above hydraulic pressure estimation calculation is performed by the controller 17. FIG. 6 shows a processing flow of pressure estimation calculation by the controller 17.

First, it is checked whether or not there is an error in the signals from the stroke sensors 19, 21, 23 of various actuators (S1). If there is an error, the hydraulic pressure is considered to be at a predetermined reference value (S8). If there is no error, it is checked whether the state of the pressure switch 9 has changed (S2). If there is no change in the state of the pressure switch,
Next, it is checked whether or not the power has just been turned on (S3).
Immediately after the power is turned on, the process proceeds to step S8 and the hydraulic pressure is considered to be at a predetermined reference value. If it is not immediately after the power is turned on, the process proceeds to step S4.

In step S4, the oil consumption of the clutch actuator 13, the select and shift actuator 15 is calculated. This is obtained by multiplying the stroke amount of each actuator by the cylinder cross-sectional area, as described above. Next, it is determined whether the motor 5 is being driven (S5). If the motor is being driven, the hydraulic pressure is calculated according to the above-mentioned formula 3 (S6), and if the motor is stopped, the hydraulic pressure is calculated according to the above-mentioned formula 2 (S7).

By the way, in step S2, the pressure switch 9
If it is determined that the state of (1) has changed, the process proceeds to step S9, and the changed switch state is checked. And
When the switch is on, the hydraulic pressure is lower threshold P
It is determined to be 1 (S10), and when it is off, it is determined that the hydraulic pressure is at the upper threshold value P2 (S11). Then, the oil consumption of each actuator is cleared to 0 (S1
2) The flag indicating whether or not the power has just been turned on is returned to the state indicating "not immediately after" (S13).

The processes of steps S9 to S13 are to judge that the oil pressure is at the lower threshold value P1 or the upper threshold value P2 when the on / off state of the pressure switch 9 is switched. . The changing hydraulic pressure after this is estimated by the processing of S4 to S7 described above.

[0023]

As described above, according to the present invention,
Since the hydraulic pressure is calculated from the oil consumption in the hydraulic circuit by using the relationship between the accumulated oil amount in the accumulator and the hydraulic pressure, it is possible to estimate the linear hydraulic pressure without using an expensive pressure sensor. .

[Brief description of drawings]

FIG. 1 is a block diagram showing a hardware configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing operating characteristics of a pressure switch.

FIG. 3 is a cross-sectional view showing a structure of an accumulator.

FIG. 4 is a diagram showing a relationship between oil consumption and oil based on characteristics of an accumulator.

FIG. 5 is a diagram showing a relationship between motor drive time and hydraulic pressure based on characteristics of a hydraulic pump.

FIG. 6 is a flowchart showing a process of a controller for estimating hydraulic pressure.

[Explanation of symbols]

 1 Hydraulic Pressure Generation Section 3 Hydraulic Pump 5 Motor 7 Accumulator 9 Pressure Switch 13 Clutch Actuator 15 Shift Select Actuator 17 Controller 19 Clutch Sensor 21 Select Sensor 23 Shift Sensor

Claims (1)

[Claims] 1. A pressure switch that is turned on / off with a predetermined hysteresis characteristic with respect to a hydraulic pressure supplied to a load, and an accumulator that stores oil to be supplied to the load and generates a hydraulic pressure according to the amount of the oil. A device for estimating a hydraulic pressure in a hydraulic circuit having: a means for measuring an oil consumption amount due to the load from the time when the on / off state of the pressure switch is switched; Means for calculating the amount of change in the oil pressure according to a known oil consumption-oil pressure characteristic of the accumulator, a predetermined threshold value for switching the on / off state of the pressure switch, and the calculated oil pressure change A hydraulic pressure estimating device, comprising: means for calculating the hydraulic pressure based on an amount.