KR101968409B1 - Hydraulic apparatus with a pressure sensor calibration means and a calibrating method thereof - Google Patents

Abstract

According to an aspect of the present invention, there is provided a hydraulic device including a correction means for a pressure sensor, comprising: a sump for storing a working fluid; A pump for circulating the working fluid stored in the sump; A hydraulic circuit extending between the sump and the pump; A pressure sensor for measuring a pressure of a working fluid circulating through the hydraulic circuit; And a controller for controlling the operation of the pump based on the data provided from the pressure sensor, wherein the controller is configured to control the data supplied from the pressure sensor in a state where the pump is stopped for a predetermined holding time (t) The pressure is measured on the basis of the measured pressure, and the measured pressure value is determined as the correction value.

Description

TECHNICAL FIELD [0001] The present invention relates to a hydraulic device having a pressure sensor correcting means,

The present invention relates to a hydraulic device including a correction means of a pressure sensor.

BACKGROUND ART [0002] Mechanisms that operate by using hydraulic pressure as a power source in connection with a power train of an automobile are widely known. For example, a vehicular friction clutch device or a power distributing device and the like, and has a system for supplying a working fluid so as to have a required pressure in accordance with the running condition of the vehicle and environmental parameters. Such hydraulic devices typically include a pump as an actuator for generating hydraulic pressure and a sump or tank for storing working fluid.

In recent years, as the performance level required for a vehicle gradually increases, it becomes necessary to control the hydraulic pressure supplied through the hydraulic system more precisely. To this end, the hydraulic system includes a pressure sensor for measuring the supplied hydraulic pressure and a controller for adjusting the hydraulic pressure supplied based on the measured data using the pressure sensor.

In such a hydraulic system, accurate pressure measurement through a pressure sensor can be adjusted so that the pressure of the supplied fluid can be adjusted to correspond to a required level, so that the performance of the pressure sensor becomes an important factor. In addition, it is important to keep the accuracy and characteristics of the pressure sensor constant.

In this regard, in order to maintain the characteristics of the pressure sensor, the hydraulic system requires periodic pressure sensor calibration. That is, the characteristics of the vehicle not only change as the travel distance and the use period of the vehicle increase, but also change depending on the environmental conditions of the place where the vehicle is used. Therefore, accurate measurement of pressure can be performed only by periodically correcting the measured value of the pressure sensor in accordance with the change of the condition.

Therefore, a correction means for a pressure sensor provided in the hydraulic device as described above is required.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a hydraulic device including a pressure sensor correcting means and capable of easily and accurately performing a pressure sensor correction in a hydraulic device, .

It is another technical object of the present invention to provide a pressure sensor correction method for a hydraulic device as described above.

According to one aspect of the present invention, there is provided a sump comprising: a sump for storing a working fluid; A pump for circulating the working fluid stored in the sump; A hydraulic circuit extending between the sump and the pump; A pressure sensor for measuring a pressure of a working fluid circulating through the hydraulic circuit; And a controller for controlling the operation of the pump based on the data provided from the pressure sensor, wherein the controller is configured to control the data supplied from the pressure sensor in a state where the pump is stopped for a predetermined holding time (t) The pressure is measured on the basis of the measured pressure, and the measured pressure value is determined as the correction value.

Here, the sump or the hydraulic circuit may be exposed to atmospheric pressure at least at one point.

The apparatus further includes a temperature sensor for measuring the temperature of the working fluid, and the controller may change the holding time t according to the measured temperature.

Also, the holding time t may be set longer as the measured temperature is lower.

In addition, the controller can determine that the pressure sensor is abnormal when the determined correction value deviates from a predetermined allowable value.

According to another aspect of the present invention, there is provided a sump comprising: a sump for storing a working fluid; A pump for circulating the working fluid stored in the sump; A hydraulic circuit extending between the sump and the pump; A pressure sensor for measuring a pressure of a working fluid circulating through the hydraulic circuit; And a controller for controlling the operation of the pump based on the data provided from the pressure sensor, the method comprising the steps of: detecting an operation stoppage time of the pump; Determining whether the stop time exceeds a predetermined hold time (t); And a pressure value measured when the stop time exceeds the holding time (t).

Here, the method further comprises the step of measuring the temperature of the working fluid, and the holding time t may be set differently depending on the temperature.

In addition, it may further include determining that the pressure sensor is abnormal when the determined correction value is out of the predetermined tolerance.

According to aspects of the present invention as described above, since the pressure sensor is calibrated in a state where the internal pressure that can be remained by the previous operation is completely eliminated after the operation of the pump is stopped in the correction process of the pressure sensor, Correction can be performed.

In addition, it is possible to determine whether or not the pressure sensor is abnormal by using the calculated correction value, thereby preventing a malfunction of the vehicle due to the sensor error.

1 is a block diagram schematically showing an embodiment of a hydraulic apparatus according to the present invention.
FIG. 2 is a view schematically showing a structure of a power transmission apparatus for a four-wheel drive vehicle to which the embodiment is applied and a method of operation thereof.
3 is a graph showing current, voltage and sensor output voltage applied to the pump before pressure sensor calibration.
4 is a flowchart showing a correction process of the pressure sensor in the embodiment shown in FIG.

Hereinafter, embodiments of a hydraulic apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram schematically illustrating an embodiment of a hydraulic device according to the present invention. Referring to FIG. 1, a hydraulic device according to the present invention includes a sump 10 for storing a working fluid, And a pump 20 for circulating the stored working fluid. Here, the pump 20 may employ any kind of pump, and in the illustrated example, an electric pump capable of easily controlling the flow rate by the controller is employed.

The electric pump has a separate motor for driving the impeller, and can control the voltage applied to the motor to circulate the working fluid at a flow rate required by the system. To this end, a controller 30 for controlling the motor is provided. The controller 30 controls the flow rate of the working fluid by controlling the voltage supplied to the motor as described above.

Here, the hydraulic device includes a pressure sensor 40 for measuring the flow rate or pressure of the working fluid, and the pressure sensor 40 is connected to the hydraulic circuit 50 including the sump 10 and the pump 20, And measures the pressure of the working fluid flowing therein and transmits it to the controller (30). The pressure value thus transmitted is used to control the pump so as to supply the fluid with the pressure required by the system.

On the other hand, the hydraulic circuit 50 supplies a working fluid to an actuator composed of the cylinder 122 and the piston 124. Specifically, the fluid is supplied into the pressure chamber 126 determined by the cylinder 122 and the piston 124, and the fluid thus supplied functions as a power source for operating the system.

For example, the fluid machine can be applied to the four-wheel drive vehicle power transmission apparatus shown in Fig. Referring to FIG. 2, a plurality of first plates 112 interlock with a first axis (not shown); A plurality of second plates (114) interposed between the first plates (112) and interlocking with a second axis (not shown); Contact means 120 for reducing the distance between the first plates 112 to contact the second plate 114 with the first plate 112; And a separating means 130 for separating the second plate 114 from the first plate 112 by widening an interval between the first plate 112 and the first plate 112, A cylinder 122 having a first end; A piston 124 reciprocating within the cylinder 122 and contacting and spacing the plate laminate 110 as a lamination of the plurality of first plates 112 and the plurality of second plates 114; A pressure chamber 126 for applying pressure to the piston 124 such that the piston 124 is moved toward the plate laminate 110; And a sealing member 128 interposed between the cylinder 122 and the piston 124 to seal the space between the plate accommodating space in which the plate laminate 110 is provided and the pressure chamber 126 .

The control method of the power transmission apparatus may include controlling the pressure of the pressure chamber 126 to reciprocate the piston 124 so that the plurality of first plates 112 and the plurality of second plates 114 ).

Calculating a required pressure P to be applied to the pressure chamber 126 to satisfy a required torque amount to be transmitted through the first plate 112 and the second plate 114; And a pressure adjusting step of adjusting the pressure in the pressure chamber 126 to the required pressure P after the required pressure calculating step is completed. Here, when the pressure adjusting step is completed, the flow returns to the required pressure calculating step.

According to this control method, in the initial startup state, the pressure in the pressure chamber 126 is zero, the piston 124 is spaced from the plate laminate 110, and the plurality of first plates 112 and the plurality of second plates 114 is zero.

Next, for example, in a power cut-off state after the power transmission is not performed as in the case immediately after starting, a predetermined first pressure P1 is applied to the pressure chamber 126, and the piston 124 Wherein the transmission torque between the plurality of first plates and the plurality of second plates is greater than zero and less than zero, ).

A second pressure P2 higher than the first pressure P1 is applied to the pressure chamber 126 in the power transmission state and the piston 124 is moved to the plate stack 110 And the transfer torque between the plurality of first plates 112 and the plurality of second plates 114 is greater than zero (0) It becomes a large value.

Then, when returning to the power cut-off state after power transmission, the first pressure P1 is applied to the pressure chamber 126, and the piston 124 returns to the initial position according to the intention of the piston 124, A preload is applied to the laminate 110 and the transmission torque between the plurality of first plates 112 and the plurality of second plates 114 is intended to be equal to zero.

In this way, the pressure in the pressure chamber 126 varies in various values during the operation of the power transmission device. In addition, in the case of a system that delivers the transmission torque to any value, rather than merely on-off, the pressure in the pressure chamber must be adjusted very precisely.

To this end, a feedback control system using a pressure sensor is provided. In order for the control system to operate correctly, the pressure sensor needs to be controlled such that the measured value from the pressure sensor matches the actual pressure.

3 is a graph showing the voltage and current applied to the pump and the output from the pressure sensor. When the operation of the pump is stopped in FIG. 3, that is, when the voltage or current applied to the pump is zero, the output voltage from the pressure sensor should be zero in principle. However, when the output voltage of the pressure sensor is changed in FIG. 3, the sensor output voltage decreases over a considerable period of time after the voltage or current applied to the motor is cut off, and finally converges to about 0.02V .

It can be interpreted that the pressure in the hydraulic circuit does not immediately become zero even if the pump is stopped, but the residual pressure exists for a considerable period of time due to the influence of viscosity and density of the fluid. In addition, the reason why the sensor output value does not become 0 even after a considerable period of time is due to the characteristic change due to the environment in which the vehicle is used and repetition of use, and a correction value corresponding to the corresponding value should be applied in the subsequent measurement.

Also, in calculating the correction value, it is understood that measurement and correction value calculation must be performed after the time when the residual pressure is eliminated rather than immediately after the voltage applied to the motor is cut off. Therefore, the embodiments of the present invention perform the correction after the sufficient time has elapsed for the residual pressure to be eliminated in performing the pressure sensor correction.

Referring to FIG. 4, the correction process in the above embodiment is shown. The process begins with the engine starting. When the engine is started, the control unit compares the time when the engine is stopped with the time required to resolve the residual pressure, that is, the reference time. If the stopped time does not exceed the reference time, the residual pressure has not been solved yet and correction can not be performed. Therefore, the correction value stored in the memory is used as it is.

If the time at which the engine is stopped exceeds the reference time, the correction value is determined because the residual pressure is canceled and correction is possible. Here, the correction value is set to a value obtained by subtracting a voltage value actually output from a voltage value (here, 0 V) to be outputted when the pressure is not applied by the pump, that is, the atmospheric pressure condition. However, such a correction value is meaningful only within a certain permissible range, and a correction value calculated to exceed the permissible range may mean that there is an abnormality in the pressure sensor.

Therefore, after calculating the correction value, it is checked whether or not the value is within the allowable range. If the value is within the permissible range, the correction value is used as the correction value. Otherwise, the previously determined correction value is utilized. Here, a step of warning the user that there is an abnormality in the pressure sensor may be added.

Meanwhile, the above-described process is a correction process that proceeds at the time of initial startup, but in order to increase the accuracy, or in the case of long-distance operation, the above-described correction process may be performed even while the vehicle is in operation.

That is, when the correction of the pressure sensor is to be performed during the running of the vehicle, the correction is performed while the operation of the pump is stopped so as not to hinder the running of the vehicle. For example, the power transmission device may be inactivated when the gear is in neutral or parking mode for a long period of time while the engine is running, or when the engine continues to operate in a fuel consumption-oriented operation mode (so-called eco mode). Therefore, if the pump maintains the stopped state for more than the reference time even during operation, the correction value can be calculated.

The process is the same as described above, and the two correction processes may be performed only one of them, and all of them may be performed as shown in FIG.

On the other hand, the reference time may be a value determined in advance according to the characteristics of the vehicle, but it may be set differently in consideration of environmental conditions. That is, the reference time means a time at which the residual pressure is canceled, which is a value depending on the viscosity of the working fluid. Therefore, the viscosity of the working fluid increases because the atmospheric temperature is low or the temperature of the working fluid is not sufficiently high at the initial stage of starting, thereby increasing the time until the residual pressure is relieved.

On the other hand, when the temperature is high, the viscosity is also lowered, so that the residual pressure is more quickly resolved. Therefore, in determining the reference time, the temperature of the working fluid may be measured and the reference time may be set differently according to the measured temperature. For example, in the example shown in FIG. 1, it is also possible to consider an example in which a temperature sensor for measuring the temperature of the working fluid is additionally installed in addition to the pressure sensor, and the measured value is sent to the controller to determine the reference time have.

At this time, the reference time may be set to be relatively long if the temperature of the working fluid is low, and may be set relatively short if the temperature is high.

10 Sump
20 Pump
30 controller
40 Pressure sensor
50 Hydraulic circuit
122 cylinders
124 piston
126 Pressure chamber

Claims (8)

A sump for storing working fluid;
A pump for circulating the working fluid stored in the sump;
A hydraulic circuit extending between the sump and the pump;
A pressure sensor for measuring a pressure of a working fluid circulating through the hydraulic circuit; And
And a controller for controlling operation of the pump based on data provided from the pressure sensor,
Wherein the controller measures the pressure on the basis of data provided from the pressure sensor while the pump is stopped for a predetermined holding time (t) or longer and determines the measured pressure value as the correction value. The method according to claim 1,
Wherein said sump or said hydraulic circuit is exposed to atmospheric pressure at at least one point. The method according to claim 1,
Further comprising a temperature sensor for measuring the temperature of the working fluid, wherein the controller varies the holding time (t) according to the measured temperature. The method of claim 3,
Wherein the holding time (t) is set longer as the measured temperature is lower. The method according to claim 1,
Wherein the controller determines that the pressure sensor is abnormal when the determined correction value deviates from a predetermined allowable value. A sump for storing working fluid;
A pump for circulating the working fluid stored in the sump;
A hydraulic circuit extending between the sump and the pump;
A pressure sensor for measuring a pressure of a working fluid circulating through the hydraulic circuit; And
And a controller for controlling the operation of the pump based on data provided from the pressure sensor,
Detecting an operation stoppage time of the pump;
Determining whether the stop time exceeds a predetermined hold time (t); And
And determining a correction value based on a pressure value measured when the stop time exceeds the holding time (t). The method according to claim 6,
Further comprising the step of measuring the temperature of the working fluid, wherein said holding time (t) is differently set according to said temperature. 8. The method of claim 7,
And determining that the pressure sensor is abnormal if the determined correction value deviates from a predetermined allowable value.

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