JP7655091B2 - Hydraulic control device for automatic transmission - Google Patents

Description

The present invention relates to a hydraulic control device for an automatic transmission mounted on a vehicle.

Automatic transmissions installed in vehicles generally have multiple planetary gear sets (planetary gear mechanisms) and multiple frictional engagement elements such as clutches and brakes. This type of automatic transmission is configured to selectively engage the multiple frictional engagement elements to selectively switch the power transmission path that passes through each planetary gear set, thereby achieving a gear shift that corresponds to the driving state of the vehicle.

The frictional engagement element of an automatic transmission includes multiple friction plates, a piston that presses the multiple friction plates together to engage them, and a hydraulic chamber to which hydraulic oil is supplied to urge the piston in the direction of engagement. The frictional engagement element is designed to be engaged or released by supplying or discharging the hydraulic pressure of the hydraulic oil to or from the hydraulic chamber.

The hydraulic pressure of the hydraulic oil generated by the oil pump is supplied to each of the hydraulic chambers of the multiple frictional fastening elements through a first oil passage common to the multiple frictional fastening elements connected to the oil pump and a second oil passage branching from the first oil passage and connected to each frictional fastening element. The hydraulic pressure supplied to the frictional fastening elements is controlled to suppress shocks and improve responsiveness when the frictional fastening elements are engaged.

The properties of the hydraulic oil supplied to the hydraulic chamber of the frictional fastening element, such as viscosity, change depending on the oil temperature. For this reason, automatic transmissions are equipped with an oil temperature sensor that detects the oil temperature, and the hydraulic pressure is controlled depending on the oil temperature detected by the oil temperature sensor. To ensure that the oil temperature of an automatic transmission is at an appropriate temperature, an oil temperature sensor abnormality determination device that determines whether there is an abnormality in the oil temperature sensor is also known (see, for example, Patent Document 1).

JP 2010-180927 A

In an automatic transmission, in order to precisely control the hydraulic pressure supplied to each of the multiple frictional engagement elements, an oil temperature sensor may be placed in an oil passage common to the multiple frictional engagement elements connected to an oil pump to detect the oil temperature, and the flow rate of hydraulic oil supplied to each of the multiple frictional engagement elements may be calculated based on the oil temperature to control the hydraulic pressure. In such cases, it is desirable to improve the detection accuracy of the oil temperature sensor in order to precisely control the hydraulic pressure control of the automatic transmission.

In response to this, it is possible to use a high-precision oil temperature sensor with improved accuracy across the entire temperature range instead of a normal oil temperature sensor. However, using a high-precision oil temperature sensor with improved accuracy across the entire temperature range can result in increased costs.

The present invention aims to provide a hydraulic control device for an automatic transmission that supplies hydraulic pressure from an oil pump to multiple frictional fastening elements, and that can accurately detect the oil temperature of the automatic transmission while suppressing increases in cost.

The present invention provides a hydraulic control device for an automatic transmission that supplies hydraulic pressure from an oil pump to a plurality of frictional fastening elements through a first oil passage common to the plurality of frictional fastening elements and a plurality of second oil passages branching off from the first oil passage, and that includes a first oil temperature sensor that detects the oil temperature in the first oil passage, a plurality of second oil temperature sensors that detect the oil temperatures in the plurality of second oil passages, respectively, and an oil temperature correction means that corrects the oil temperature detected by the first oil temperature sensor using the oil temperatures detected by the plurality of second oil temperature sensors, respectively.

According to the present invention, a first oil temperature sensor is provided that detects the oil temperature of a first oil passage common to a plurality of frictional fastening elements, and a plurality of second oil temperature sensors are provided that detect the oil temperatures of a plurality of second oil passages that respectively supply hydraulic pressure to a plurality of frictional fastening elements, and an oil temperature correction means corrects the oil temperature detected by the first oil temperature sensor using the oil temperatures detected by the plurality of second oil temperature sensors. Since the first oil temperature sensor is learned and corrected using the plurality of second oil temperature sensors, the detection accuracy of the first oil temperature sensor can be improved, and the oil temperature of the automatic transmission can be detected with high accuracy.

As the first oil temperature sensor, a first oil temperature sensor with improved accuracy by calibrating only the high temperature range above a predetermined temperature such as 40 degrees is used, and the oil temperature is accurately detected by the first oil temperature sensor in the high temperature range, and in the low temperature range below the predetermined temperature where the variation in the oil temperature detected by the second oil temperature sensor is small, the oil temperature detected by the first oil temperature sensor is learned and corrected using the oil temperatures detected by the multiple second oil temperature sensors, thereby making it possible to accurately detect the oil temperature of the automatic transmission in the low temperature range and the high temperature range. The oil temperature of the automatic transmission can be accurately detected without using an expensive, high-precision oil temperature sensor as the first oil temperature sensor that is calibrated in the high temperature range and the low temperature range respectively to improve accuracy over the entire temperature range.

Therefore, in an automatic transmission in which hydraulic pressure from an oil pump is supplied to multiple frictional fastening elements, the oil temperature of the automatic transmission can be detected with high accuracy while suppressing increases in costs compared to when the oil temperature is detected using only the first oil temperature sensor.

It is preferable that the oil temperature correction means corrects the oil temperature when the oil temperatures detected by each of the second oil temperature sensors are within a predetermined range.

With this configuration, the oil temperature is corrected when the oil temperatures detected by the multiple second oil temperature sensors are within a predetermined range. Therefore, when the oil temperatures detected by the multiple second oil temperature sensors are low and within a predetermined range with little variation in oil temperature, such as after a predetermined time has elapsed since the engine was stopped, the oil temperatures detected by the multiple second oil temperature sensors can be used to improve the detection accuracy of the first oil temperature sensor.

It is preferable that the oil temperature correction means corrects the oil temperature detected by the first oil temperature sensor based on the average value of the oil temperatures detected by the first oil temperature sensor and the multiple second oil temperature sensors.

With this configuration, the oil temperature detected by the first oil temperature sensor is corrected based on the average value of the oil temperatures detected by the first oil temperature sensor and the multiple second oil temperature sensors, making it relatively easy to improve the detection accuracy of the first oil temperature sensor.

It is preferable that a plurality of hydraulic pressure sensors are provided to detect the hydraulic pressure of the second oil passages, and that the second oil temperature sensor is integrally provided with the hydraulic pressure sensor.

With this configuration, the second oil temperature sensor is integrally provided with the hydraulic pressure sensor that detects the hydraulic pressure of the second oil passage, so the oil temperature sensor integrally provided with the hydraulic pressure sensor can be used as the second oil temperature sensor, and the accuracy of oil temperature detection by the first oil temperature sensor can be improved while suppressing increases in costs without providing a separate second oil temperature sensor.

The oil temperature detected by the first oil temperature sensor can be used to calculate the flow rate of hydraulic oil to be supplied to each of the multiple frictional fastening elements.

With this configuration, the oil temperature detected by the first oil temperature sensor is used to calculate the flow rate of hydraulic oil to be supplied to each of the multiple frictional fastening elements. Therefore, when the oil temperature is used to calculate the flow rate of hydraulic oil to be supplied to each of the multiple frictional fastening elements and control the hydraulic pressure to be supplied to each of the multiple frictional fastening elements, the oil temperature can be detected with high accuracy and the hydraulic pressure to be supplied to each of the multiple frictional fastening elements can be controlled with high accuracy.

It is preferable that the first oil temperature sensor is configured to have higher accuracy in a high temperature range above a predetermined temperature than in a low temperature range below the predetermined temperature.

With this configuration, the first oil temperature sensor is configured to be more accurate in the high temperature range than in the low temperature range, so costs can be kept down compared to using an expensive oil temperature sensor that is calibrated separately for the high and low temperature ranges to increase accuracy across the entire temperature range.

The hydraulic control device for an automatic transmission according to the present invention can accurately detect the oil temperature of an automatic transmission in which hydraulic pressure from an oil pump is supplied to each of a number of frictional fastening elements while suppressing increases in cost.

1 is a circuit diagram showing a main portion of a hydraulic control circuit for an automatic transmission according to an embodiment of the present invention; FIG. 4 is an explanatory diagram for explaining a tolerance of an oil temperature sensor. 1 is a block diagram showing a hydraulic control device for an automatic transmission; FIG. 4 is a diagram showing a target correction temperature range of the oil temperature sensor. FIG. 11 is a diagram showing a target correction temperature characteristic used for initial oil temperature correction. FIG. 4 is a diagram showing a target correction temperature characteristic and an execution correction temperature characteristic used in normal oil temperature correction. FIG. 13 is a diagram showing correction reflection characteristics. 5 is a flowchart showing a temperature correction control for an oil temperature sensor. FIG. 11 is another diagram showing the correction reflection characteristic.

The following describes an embodiment of the present invention with reference to the attached drawings.

Figure 1 is a circuit diagram showing the main parts of a hydraulic control circuit for an automatic transmission according to an embodiment of the present invention. The automatic transmission according to an embodiment of the present invention is mounted on a vehicle such as, but not limited to, a front-engine, rear-drive vehicle, and receives power from the engine. The automatic transmission includes a transmission mechanism in a transmission case, on the axis of an input shaft connected to the engine, the transmission mechanism including multiple planetary gear sets and multiple frictional fastening elements such as clutches and brakes.

The automatic transmission is configured so that the power transmission path passing through each planetary gear set is selectively switched by selectively engaging a plurality of frictional engagement elements that constitute the transmission mechanism, thereby achieving a gear shift stage according to the driving state of the vehicle. The automatic transmission has four planetary gear sets and five frictional engagement elements consisting of three clutches and two brakes, and is configured so that eight forward gears and a reverse gear are formed by selectively engaging three of these frictional engagement elements.

The automatic transmission is connected to the engine without going through a fluid transmission device such as a torque converter, and is provided with a power on/off clutch as a frictional fastening element between the engine and the input shaft of the automatic transmission. The power on/off clutch is configured to be able to connect and disconnect between the output shaft of the engine and the input shaft of the automatic transmission. When the power on/off clutch is engaged, power can be transmitted between the engine and the automatic transmission.

In an automatic transmission, a drive sprocket for driving an oil pump is connected to the engine output shaft and arranged coaxially between the engine and the power connecting/disconnecting clutch, and an oil pump located inside the transmission case and radially away from the axis of the automatic transmission is driven via a chain.

In this embodiment, the automatic transmission has six frictional fastening elements, consisting of five frictional fastening elements that make up the shift mechanism and a frictional fastening element that makes up the power engagement/disengagement clutch. Each frictional fastening element has multiple friction plates, a piston that presses the multiple friction plates to engage them, and a hydraulic chamber to which hydraulic oil is supplied to urge the piston in the engagement direction, and is adapted to be engaged or released by supplying or discharging the hydraulic pressure of the hydraulic oil to or from the hydraulic chamber.

As shown in FIG. 1, the automatic transmission 1 has a hydraulic control circuit 20 that selectively supplies hydraulic pressure from the oil pump 2 to multiple, specifically six, frictional engagement elements 10 to transmit power from the engine to the automatic transmission 1 and achieve a desired gear shift.

The hydraulic control circuit 20 is configured so that the hydraulic pressure of the working oil generated by the oil pump 2, which serves as a hydraulic pressure supply source that supplies hydraulic pressure, is supplied to the hydraulic chambers of the multiple frictional fastening elements 10 via a first oil passage 21 that is common to the multiple frictional fastening elements 10 connected to the oil pump 2, and a second oil passage 22 that branches off from the first oil passage 21 and is connected to each frictional fastening element 10.

The first oil passage 21 is provided with a pressure regulating valve 3 that adjusts the discharge pressure of the oil pump 2 to a line pressure of a specified hydraulic pressure, as well as a specified hydraulic circuit 4 that includes a manual valve that switches the supply destination of the line pressure according to the range selected by the driver, and a shift valve that switches the supply and discharge of hydraulic pressure to the multiple frictional engagement elements 10.

Each of the second oil passages 22 is provided with a solenoid valve 11 that controls the hydraulic pressure supplied to the frictional engagement element 10. A linear solenoid is used as the solenoid valve 11. The solenoid valve 11 is configured to operate so as to adjust the hydraulic pressure input to the source pressure port to a control pressure of a predetermined hydraulic pressure, i.e., the hydraulic pressure to be supplied to the hydraulic chamber, and output the adjusted hydraulic pressure to the output port, or to shut off communication between the source pressure port and the output port and connect the output port to the drain port, thereby supplying and discharging the hydraulic pressure to be supplied to the frictional engagement element 10. The solenoid valve 11 is controlled by the control unit 30 together with the pressure regulating valve 3 and other solenoid valves in the predetermined hydraulic circuit 4.

A hydraulic pressure sensor 12 that detects the hydraulic pressure of the second oil passage 22 is disposed downstream of the solenoid valve 11 in the second oil passage 22. The hydraulic pressure detected by the hydraulic pressure sensor 12 is used to calculate the flow rate of hydraulic oil supplied to each frictional fastening element 10 and to control the hydraulic pressure of each frictional fastening element 10. An oil temperature sensor (second oil temperature sensor) 13 that detects the oil temperature of the second oil passage 22 is integrally provided in the hydraulic pressure sensor 12, and the hydraulic pressure sensor 12 uses the oil temperature detected by the second oil temperature sensor 13 to monitor whether the temperature of the hydraulic pressure sensor 12 has increased due to an overcurrent or the like.

The second oil temperature sensor 13, which is integral with the oil pressure sensor 12, is a temperature sensor equipped with a thermistor or the like whose resistance decreases as the temperature rises, and is configured so that the detection accuracy is within a first predetermined range, such as ±1 degree, in high temperature ranges above a predetermined temperature, such as 40 degrees, and in low temperature ranges below the predetermined temperature.

In the automatic transmission 1, an oil temperature sensor (first oil temperature sensor) 14 that detects the oil temperature in the first oil passage 21 is provided in the first oil passage 21. The first oil temperature sensor 14 is provided downstream of the pressure regulating valve 3 and upstream of the specified hydraulic circuit 4 in the first oil passage 21 connected to the oil pump 2. A temperature sensor equipped with a thermistor or the like is used as the first oil temperature sensor 14.

The first oil temperature sensor 14 is calibrated in a high temperature range above a predetermined temperature such as 40 degrees, and is configured to have higher accuracy in the high temperature range than in a low temperature range below the predetermined temperature. The first oil temperature sensor 14 has a detection accuracy within a first predetermined range such as ±1 degree in a low temperature range below the predetermined temperature, but in a high temperature range above the predetermined temperature, the detection accuracy is increased so that it is within a second predetermined range smaller than the first predetermined range such as ±0.5 degrees.

Figure 2 is an explanatory diagram explaining the tolerance of the oil temperature sensor. In Figure 2, the first oil temperature sensor 14 is shown with temperature (°C) on the horizontal axis and detection accuracy (°C), which is the tolerance of the oil temperature sensor, on the vertical axis. Compared to a normal oil temperature sensor that has a nearly constant tolerance W1 regardless of temperature as shown by the two-dot chain line L1 in Figure 3, the first oil temperature sensor 14 is highly accurate, calibrated so that the tolerance W2 is equal to or less than a predetermined value in the high temperature range above a predetermined temperature Ta, such as 40 degrees, as shown by the solid line L2 in Figure 3.

The first oil temperature sensor 14 is calibrated and configured to have high accuracy in the high temperature range, so that the tolerance W3 decreases as the temperature increases even in the low temperature range below the desired temperature Ta, but is still larger than the tolerance W2. The first oil temperature sensor 14 is configured to have higher accuracy in the high temperature range than in the low temperature range.

In the low temperature range below a predetermined temperature Ta, the first oil temperature sensor 14 learns and corrects the oil temperature detected by the first oil temperature sensor 14 by using the oil temperatures detected by the multiple second oil temperature sensors 13, and is configured to increase accuracy in the low temperature range, as shown by the dashed line L3 in Figure 3.

As mentioned above, the oil temperature detected by the first oil temperature sensor 14 is used to calculate the flow rate of hydraulic oil supplied to each frictional fastening element 10, and is used for hydraulic control of each frictional fastening element 10, etc.

When calculating the flow rate of hydraulic oil supplied to each frictional fastening element 10, the differential pressure between the indicated pressure for the solenoid valve 11 provided in the second oil passage 22 and the hydraulic pressure detected by the hydraulic sensor 12 provided in the second oil passage 22 is calculated, and the inflow flow rate of hydraulic oil into the hydraulic chamber of the frictional fastening element 10 is calculated using characteristic data showing the relationship between the differential pressure and the inflow flow rate of hydraulic oil into the hydraulic chamber of the frictional fastening element 10, and the cumulative flow rate of hydraulic oil supplied to the hydraulic chamber of the frictional fastening element 10 is calculated. Then, the predicted hydraulic pressure of the hydraulic chamber is calculated from the calculated cumulative flow rate of hydraulic oil supplied to the hydraulic chamber of the frictional fastening element 10, and the hydraulic pressure supplied to the frictional fastening element 10 is controlled based on the predicted hydraulic pressure.

The characteristic data showing the relationship between the differential pressure and the inflow flow rate of the hydraulic oil into the hydraulic chamber of the frictional engagement element 10 depends on the temperature of the hydraulic oil, and is set so that the inflow flow rate increases as the oil temperature increases and decreases as the oil temperature decreases. The flow rate of the hydraulic oil to be supplied to each frictional engagement element 10 is calculated using the characteristic data according to the oil temperature detected by the first oil temperature sensor 14. The calculation of the flow rate of the hydraulic oil to be supplied to each frictional engagement element 10 is performed by the control unit 30.

The control unit 30 corrects the oil temperature detected by the first oil temperature sensor 14 using the oil temperatures detected by the multiple second oil temperature sensors 13, so as to increase the detection accuracy of the oil temperature detected by the first oil temperature sensor 14.

Figure 3 is a block diagram showing a hydraulic control device for an automatic transmission. As shown in Figure 3, the hydraulic control device 40 for an automatic transmission includes a control unit 30 that controls each solenoid valve 11 in the hydraulic control circuit 20 to form a gear stage according to the driving state.

The control unit 30 receives inputs of a range sensor 5 that detects the range selected by the driver's operation, a vehicle speed sensor 6 that detects the vehicle speed, an accelerator opening sensor 7 that detects the amount of depression of the accelerator pedal (accelerator opening) by the driver, multiple oil pressure sensors 12 that detect the oil pressure supplied to each of the multiple frictional fastening elements, a first oil temperature sensor 14 that detects the oil temperature in the first oil passage 21, multiple second oil temperature sensors 13 that detect the oil temperatures in each of the multiple second oil passages 22, an engine speed sensor (not shown) that detects the engine speed, and signals from a soak timer (not shown) that detects the soak time, which is the time elapsed since the engine was stopped.

Based on these signals, the control unit 30 outputs control signals to the pressure regulating valve 3 provided in the first oil passage 21 in the hydraulic control circuit 20, the multiple solenoid valves 11 provided in each of the multiple second oil passages 22, and other solenoid valves included in the specified hydraulic circuit 4, depending on the driving conditions, and selectively supplies hydraulic pressure from the oil pump 2 to each of the six frictional engagement elements 10 to transmit power from the engine to the automatic transmission 1 and form a specified gear stage depending on the driving conditions. The control unit 30 is mainly composed of a microcomputer.

As described above, the control unit 30 calculates the flow rate of hydraulic oil to be supplied to each of the multiple frictional engagement elements 10 based on the oil temperature detected by the first oil temperature sensor 14 based on various signals, and controls the hydraulic pressure to be supplied to the hydraulic chamber of each frictional engagement element 10 based on the calculated flow rate of hydraulic oil.

The control unit 30 also corrects the oil temperature detected by the first oil temperature sensor 14 using the oil temperatures detected by the multiple second oil temperature sensors 13, for example, to control the hydraulic pressure with high precision. The control unit 30 stores various data for correcting the oil temperature detected by the first oil temperature sensor 14. The control unit 30 constitutes an oil temperature correction means that corrects the oil temperature detected by the first oil temperature sensor 14 using the oil temperatures detected by the multiple second oil temperature sensors 13.

The first oil temperature sensor 14 and the second oil temperature sensor 13 each include a detection unit that detects the oil temperature, such as a thermistor having a resistance according to temperature, a measurement circuit unit that is connected to the detection unit and measures the oil temperature, and an output unit that is connected to the measurement circuit unit and outputs an output signal corresponding to the oil temperature, and are configured to detect the oil temperature.

The second oil temperature sensor 13 is configured to have a detection accuracy within a first predetermined range, such as ±1 degree, in high temperature ranges above a predetermined temperature, such as 40 degrees, and in low temperature ranges below the predetermined temperature. The first oil temperature sensor 14 has a detection accuracy within a first predetermined range, such as ±1 degree, in low temperature ranges below a predetermined temperature, such as 40 degrees, but its accuracy is increased so that in high temperature ranges above the predetermined temperature, its detection accuracy is within a second predetermined range, such as ±0.5 degrees, which is smaller than the first predetermined range. The measurement circuit section of the first oil temperature sensor 14 is formed so that its detection accuracy is within the second predetermined range in the high temperature range.

Figure 4 is a diagram showing the target correction temperature range of the oil temperature sensor. In Figure 4, the horizontal axis represents the measured temperature, and the vertical axis represents the target correction temperature, showing the target correction temperature range in which the oil temperature detected by the first oil temperature sensor 14 is corrected. The target correction temperature range is set so that the target correction temperature is between the upper limit line L4 and the lower limit line L5.

As shown in FIG. 4, the upper limit line L4 is set to 6 degrees when the temperature is between -30 degrees and -20 degrees, is set to have a predetermined slope of 6 degrees at -20 degrees and 4 degrees at 40 degrees when the temperature is between -20 degrees and 40 degrees, and is set to have a predetermined slope of 4 degrees at 40 degrees and zero at 110 degrees when the temperature is between 40 degrees and 110 degrees.

The lower limit line L5 is set to -6 degrees when the temperature is between -30 degrees and -20 degrees, is set to have a predetermined slope of -6 degrees at -20 degrees and -4 degrees at 40 degrees when the temperature is between -20 degrees and 40 degrees, and is set to have a predetermined slope of -4 degrees at 40 degrees and zero at 110 degrees when the temperature is between 40 degrees and 110 degrees.

If the target correction temperature for the measured temperature is within the target correction temperature range between the upper limit line L4 and the lower limit line L5, the target correction temperature is set, but if it is higher than the upper limit line L4, it is set to the target correction temperature of the upper limit line L4, and if it is lower than the lower limit line L5, it is set to the target correction temperature of the lower limit line L5. For example, if the target correction temperature P1 is 2 degrees at a measured temperature of 20 degrees, the target correction temperature is set to 2 degrees, but if the target correction temperature P2 is 6 degrees at a measured temperature of 40 degrees, it is set to 4 degrees, which is the target correction temperature P3 of the upper limit line L4.

In this way, when the target correction temperature for the measured temperature is set, it is set within the target correction temperature range, which prevents the target correction temperature from being set erroneously due to a malfunction of the oil temperature sensor, etc.

In a vehicle equipped with an automatic transmission 1, after a predetermined time has elapsed, such as eight hours, after the engine has been stopped, the oil temperature detected by the first oil temperature sensor 14 is corrected based on the average value of the oil temperatures detected by the first oil temperature sensor 14 and the multiple second oil temperature sensors 13.

When correcting the oil temperature detected by the first oil temperature sensor 14, an average oil temperature is calculated, which is the average value of the oil temperature detected by the first oil temperature sensor 14 (first oil temperature) and the oil temperature detected by the second oil temperature sensor 13 (second oil temperature). In the automatic transmission 1, the average oil temperature of the seven oil temperatures consisting of one first oil temperature and six second oil temperatures is calculated as the average oil temperature of the first oil temperature and the second oil temperature.

Next, an oil temperature error of the average oil temperature of the calculated first oil temperature and second oil temperature is calculated with respect to the oil temperature detected by the first oil temperature sensor 14. The difference between the average oil temperature of the first oil temperature and the second oil temperature and the first oil temperature is calculated as the oil temperature error. Then, based on the calculated oil temperature error, a target correction temperature characteristic for correcting the oil temperature detected by the first oil temperature sensor 14 is calculated.

Once the target correction temperature characteristics are calculated, an execution correction temperature characteristic is calculated that actually reflects the target correction temperature characteristics when correcting the oil temperature detected by the first oil temperature sensor 14, and the oil temperature detected by the first oil temperature sensor 14 is corrected based on the calculated execution correction temperature characteristic.

Figure 5 is a diagram showing the target correction temperature characteristic used for initial oil temperature correction. In Figure 5, the horizontal axis represents the measured temperature, and the vertical axis represents the target correction temperature, showing the target correction temperature characteristic used for initial temperature correction. In initial oil temperature correction, which corrects the oil temperature detected by the first oil temperature sensor 14 for the first time in a vehicle equipped with an automatic transmission 1, the target correction temperature characteristic line L6 as shown in Figure 5 is used.

For the target correction temperature characteristic line L6, the oil temperature error is multiplied by (-1) to set the target correction temperature T21 at the oil temperature T11 detected by the first oil temperature sensor 14. For example, if the first oil temperature is 4 degrees and the average oil temperature of the first and second oil temperatures is 6 degrees, the oil temperature error of -2 degrees is calculated by subtracting the average oil temperature of 6 degrees from the first oil temperature of 4 degrees, and the oil temperature error of -2 degrees is multiplied by (-1) to calculate the target correction temperature of 2 degrees.

For temperatures between -30 degrees and 110 degrees, the target correction temperature characteristic line L6 is set so that at temperatures higher than temperature T11, it connects the target correction temperature T21 at temperature T11 with the target correction temperature of zero at a temperature of 110 degrees, and has a predetermined slope such that the target correction temperature decreases as the temperature increases, and at temperatures lower than temperature T11, it is set to the same target correction temperature T21 as the target correction temperature T21 at temperature T11.

When the target correction temperature characteristic line L6 is calculated, an execution correction temperature characteristic is calculated that actually reflects the target correction temperature characteristic when correcting the oil temperature detected by the first oil temperature sensor 14. In the initial oil temperature correction, the correction reflection rate α that actually reflects the target correction temperature characteristic is set to 100%, and the target correction temperature characteristic is calculated as it is as the execution correction temperature characteristic.

When the execution correction temperature characteristic is calculated, the output section of the first oil temperature sensor 14 is controlled to correct the oil temperature detected by the first oil temperature sensor 14 using the execution correction temperature characteristic and output the corrected oil temperature. The next time the oil temperature is detected by the first oil temperature sensor 14, the first oil temperature sensor 14 corrects the oil temperature detected by the sensor section and the measurement circuit section using the execution correction temperature characteristic, i.e., corrects the oil temperature by adding the target correction temperature, and outputs the corrected oil temperature.

Figure 6 is a diagram showing the target correction temperature characteristic and the execution correction temperature characteristic used in normal oil temperature correction. In Figure 6, the horizontal axis represents the measured temperature, and the vertical axis represents the temperature characteristic, showing the target correction temperature characteristic and the execution correction temperature characteristic used in normal oil temperature correction. In normal oil temperature correction, which corrects the oil temperature detected by the first oil temperature sensor 14 after the initial oil temperature correction, the target correction temperature characteristic line L7 shown by the solid line in Figure 6 is used.

As with the target correction temperature characteristic line L6, the target correction temperature characteristic line L7 is set by multiplying the oil temperature error by (-1) at the oil temperature T12 detected by the first oil temperature sensor 14 to set the target correction temperature T22.

The target correction temperature characteristic line L7 is set for temperatures (T12-40) to (T12+40) degrees so that at temperatures higher than temperature T12, it connects the target correction temperature T22 at temperature T12 with the target correction temperature of zero at temperature (T12+40) degrees, and has a predetermined slope that the target correction temperature decreases as the temperature increases, and at temperatures lower than temperature T12, it connects the target correction temperature T22 at temperature T12 with the target correction temperature of zero at temperature (T12-40) degrees, and has a predetermined slope that the target correction temperature decreases as the temperature decreases.

For normal oil temperature correction, once the target correction temperature characteristic line L7 is calculated, an effective correction temperature characteristic is calculated that actually reflects the target correction temperature characteristic when correcting the oil temperature detected by the first oil temperature sensor 14.

Figure 7 is a diagram showing the correction reflection characteristics. In Figure 7, the horizontal axis represents the measured temperature, and the vertical axis represents the correction reflection rate, showing the correction reflection characteristics used for normal oil temperature correction. In initial oil temperature correction, a correction reflection characteristic line is used in which the correction reflection rate is set to 100% for temperatures from (T12-40) to (T12+40) degrees regardless of temperature, and in normal oil temperature correction, the correction reflection characteristic line L8 shown in Figure 7 is used.

For temperatures (T12-40) to (T12+40), the correction reflection rate α is set to 40% at temperature T12, and at temperatures higher than temperature T12, the correction reflection rate is set to have a predetermined slope that connects the correction reflection rate α at temperature T12 with the correction reflection rate that is zero at temperature (T12+40) degrees and the correction reflection rate decreases as the temperature increases, and at temperatures lower than temperature T12, the correction reflection rate is set to have a predetermined slope that connects the correction reflection rate α at temperature T12 with the correction reflection rate that is zero at temperature (T12-40) degrees and the correction reflection rate decreases as the temperature decreases.

In normal oil temperature correction, the actual correction temperature characteristic is calculated by multiplying the target correction temperature characteristic by the correction reflection characteristic, and the actual correction temperature characteristic line L9, as shown by the two-dot chain line in Figure 6, is calculated from the target correction temperature line L7 and the correction reflection characteristic line L8.

For temperatures (T12-40) to (T12+40), the execution correction temperature characteristic line L9 is set to an execution correction temperature αT22 obtained by multiplying the target correction temperature T22 by the correction reflection rate α at temperature T12, and is set to have a predetermined slope at temperatures higher than temperature T12, connecting the execution correction temperature αT22 at temperature T12 with the execution correction temperature that is zero at temperature (T12+40) degrees, so that the execution correction temperature decreases as the temperature increases, and is set to have a predetermined slope at temperatures lower than temperature T12, connecting the execution correction temperature αT22 at temperature T12 with the execution correction temperature that is zero at temperature (T12-40) degrees, so that the execution correction temperature decreases as the temperature decreases.

For normal oil temperature correction, once the execution correction temperature characteristic is calculated, the output section of the first oil temperature sensor 14 is controlled to correct the oil temperature detected by the first oil temperature sensor 14 using the execution correction temperature characteristic and output it. The next time the oil temperature is detected by the first oil temperature sensor 14, the first oil temperature sensor 14 corrects the oil temperature detected by the sensor section and the measurement circuit section using the execution correction temperature characteristic, i.e., corrects the oil temperature by adding the target correction temperature, and outputs it.

In this way, by repeatedly performing normal oil temperature correction, the oil temperature detected by the first oil temperature sensor 14 is learned and corrected using multiple second oil temperature sensors 13, so the oil temperature detected by the first oil temperature sensor 14 can be detected with high accuracy.

In this embodiment, when the target correction temperature characteristic is calculated, in the initial oil temperature correction, the target correction temperature characteristic data as shown in FIG. 5 is calculated as is, whereas in the normal oil temperature correction, the target correction temperature characteristic data as shown in FIG. 6 is calculated as is if it is within the target correction temperature range shown in FIG. 4, but if it is outside the target correction temperature range shown in FIG. 4, it is corrected to be within the target correction temperature range and calculated.

Figure 8 is a flowchart showing the oil temperature correction control of the oil temperature sensor, and is a flowchart showing the oil temperature correction control of the first oil temperature sensor 14. As shown in Figure 8, the oil temperature correction control for correcting the oil temperature detected by the first oil temperature sensor 14 is performed by the control unit 30.

First, various signals are read into the control unit 30 (step S1). Signals from the range sensor 5, vehicle speed sensor 6, accelerator opening sensor 7, multiple oil pressure sensors 12, first oil temperature sensor 14, multiple second oil temperature sensors 13, engine speed sensor, soak timer, etc. are read.

Next, based on the various signals read in step S1, it is determined whether or not a predetermined time has elapsed since the engine was stopped (step S2). In a vehicle equipped with an automatic transmission 1, the predetermined time after the engine was stopped is set to 8 hours. The oil temperature correction control is performed while the engine is stopped after the predetermined time has elapsed since the engine was stopped.

If the determination result in step S2 is YES, it is determined whether the oil temperatures detected by the first oil temperature sensor 14 and the multiple second oil temperature sensors 13 are within a predetermined range (step S3). An average oil temperature of the first and second oil temperatures detected by the first oil temperature sensor 14 and the second oil temperature sensor 13 is calculated, and it is determined whether the first oil temperature and the second oil temperature are within a predetermined range, such as 6 degrees, relative to the calculated average oil temperature. The oil temperatures detected by the first oil temperature sensor 14 and the second oil temperature sensor 13 are detected simultaneously. Note that the oil temperatures detected by the first oil temperature sensor 14 and the second oil temperature sensor 13 may be average values for the same predetermined period.

If the determination result in step S3 is YES, the oil temperature error between the oil temperature (first oil temperature) detected by the first oil temperature sensor 14 and the average oil temperature (average oil temperature of the first oil temperature and the second oil temperature) of the oil temperatures detected by the first oil temperature sensor 14 and the multiple second oil temperature sensors 13 is calculated (step S4).

When the oil temperature error is calculated in step S4, a target correction temperature characteristic for correcting the oil temperature detected by the first oil temperature sensor 14 is calculated based on the calculated oil temperature error (step S5). In the initial oil temperature correction, the target correction temperature characteristic is calculated as the target correction temperature characteristic line L6 as shown in FIG. 5.

When the target correction temperature characteristic is calculated in step S5, an effective correction temperature characteristic is calculated (step S6) that actually reflects the target correction temperature characteristic when correcting the oil temperature detected by the first oil temperature sensor 14. In the initial oil temperature correction, the target correction temperature characteristic is calculated as the effective correction temperature characteristic as is.

When the execution correction temperature characteristic is calculated in step S6, correction control of the oil temperature detected by the first oil temperature sensor 14 is executed based on the calculated execution correction temperature characteristic (step S7), and the process ends. The next time the oil temperature is detected by the first oil temperature sensor 14, the oil temperature detected by the first oil temperature sensor 14 is corrected by the execution correction temperature characteristic and output.

The output section of the first oil temperature sensor 14 is configured to correct the oil temperature detected by the first oil temperature sensor 14 using the execution correction temperature characteristic the next time the oil temperature is detected by the first oil temperature sensor 14, and output the corrected oil temperature. Similarly, the output section of the first oil temperature sensor 14 is also configured to correct the oil temperature detected by the first oil temperature sensor 14 using the execution correction temperature characteristic for the normal oil temperature correction performed after the initial oil temperature correction, and output the corrected oil temperature.

When the target correction temperature characteristic is calculated in step S5, in normal oil temperature correction, the target correction temperature characteristic is calculated as the target correction temperature characteristic line L7 shown by the solid line in Figure 6.

For normal oil temperature correction, once the target correction temperature characteristic is calculated in step S5, an effective correction temperature characteristic is calculated (step S6) that actually reflects the target correction temperature characteristic when correcting the oil temperature detected by the first oil temperature sensor 14. For normal oil temperature correction, a correction reflection characteristic line L8 as shown in FIG. 7 is set. For normal oil temperature correction, the effective correction temperature characteristic is calculated by multiplying the target correction temperature characteristic by the correction reflection characteristic, and an effective correction temperature characteristic line L9 as shown by the two-dot chain line in FIG. 6 is calculated.

For normal oil temperature correction, once the execution correction temperature characteristic is calculated in step S6, correction control of the oil temperature detected by the first oil temperature sensor 14 is executed based on the calculated execution correction temperature characteristic (step S7), and the process ends. The next time the oil temperature is detected by the first oil temperature sensor 14, the oil temperature detected by the first oil temperature sensor 14 is corrected using the execution correction temperature characteristic and output.

When the target correction temperature characteristic is calculated in step S5, in the initial oil temperature correction, the target correction temperature characteristic as shown in FIG. 5 is calculated as is, whereas in the normal oil temperature correction, the target correction temperature characteristic as shown in FIG. 6 is calculated as is if it is within the target correction temperature range shown in FIG. 4, but if it is outside the target correction temperature range shown in FIG. 4, it is corrected to be within the target correction temperature range and calculated.

On the other hand, if the determination result in step S2 is NO, the process ends without performing oil temperature correction control of the first oil temperature sensor 14. If a predetermined time, such as 8 hours, has not elapsed since the engine was stopped, the oil temperature detected by the multiple second oil temperature sensors 13 may be high and there may be a large variation in the oil temperature, so oil temperature correction control is not performed.

Also, if the determination result in step S3 is NO, the process ends without performing oil temperature correction control of the first oil temperature sensor 14. If the first oil temperature and the second oil temperature are not within a predetermined range with respect to the average oil temperature of the first oil temperature and the second oil temperature detected by the first oil temperature sensor 14 and the second oil temperature sensor 13, there is a risk that the first oil temperature sensor 14 and the second oil temperature sensor 13 are erroneously detecting the oil temperature, so oil temperature correction control is not performed.

In this way, in the hydraulic control device 40 for the automatic transmission according to this embodiment, the oil temperature detected by the first oil temperature sensor 14 is corrected using the oil temperatures detected by the multiple second oil temperature sensors 13, and the first oil temperature sensor 14 is learned and corrected using the multiple second oil temperature sensors 13. This improves the detection accuracy of the first oil temperature sensor 14, and enables the oil temperature of the automatic transmission to be detected with high accuracy.

Even when a first oil temperature sensor 14 with improved accuracy only in the high temperature range is used as the first oil temperature sensor 14, the oil temperature detected by the multiple second oil temperature sensors 13 is used to learn and correct the oil temperature detected by the first oil temperature sensor 14, making it possible to accurately detect the oil temperature of the automatic transmission even in the low temperature range.

In this way, the oil temperature detected by the first oil temperature sensor 14 is used to calculate the flow rate of hydraulic oil supplied to each of the multiple frictional fastening elements 10, as described above, and the calculation of the flow rate of hydraulic oil can be performed with high accuracy.

In this embodiment, it is determined whether a predetermined time, such as 8 hours, has elapsed since the engine was stopped. However, since experiments have shown that the oil temperatures detected by the second oil temperature sensors 13 are within 0.5 degrees when 8 hours have elapsed since the engine was stopped, it is also possible to determine whether the oil temperatures detected by the second oil temperature sensors 13 are within a predetermined range, such as 0.5 degrees, instead of whether a predetermined time has elapsed since the engine was stopped.

In addition, when the oil temperature error is calculated, the average oil temperature of all oil temperatures is used as the average oil temperature of the first oil temperature and the second oil temperature, but the oil temperature error may be calculated using the average oil temperature of the oil temperatures excluding the maximum oil temperature and the minimum oil temperature.

In addition, the output section of the first oil temperature sensor 14 is adapted to correct the oil temperature detected by the first oil temperature sensor 14 using the execution correction temperature characteristic before outputting it, but the oil temperature detected by the first oil temperature sensor 14 may also be corrected by the control unit 30 using the execution correction temperature characteristic before outputting it.

In addition, when the target correction temperature characteristic is calculated, in normal oil temperature correction, if the target correction temperature characteristic as shown in Figure 6 is outside the target correction temperature range shown in Figure 4, it is corrected to be within the target correction temperature range and calculated, but it is also possible to calculate the target correction temperature characteristic without setting the target correction temperature range.

In this embodiment, when the execution correction temperature characteristic is calculated, the correction reflection characteristic line L8 as shown in FIG. 7 is used in the normal oil temperature correction, but the correction reflection rate α at temperature T12 may be set to another value such as 60% instead of 40%.

Figure 9 is another diagram showing the correction reflection characteristic. Instead of the correction reflection characteristic line L8 as shown in Figure 7, the correction reflection characteristic line L7' as shown in Figure 9 may be used to calculate the execution correction temperature characteristic.

The correction reflection characteristic line L7' is set to have a predetermined slope so that the correction reflection rate α is set to 40% at temperature T12 for temperatures (T12-40) to (T12+40), and at temperatures higher than temperature T12, the correction reflection rate is 40% at temperature T12, 20% at temperature (T12+10), 10% at temperature (T12+20), and zero at temperature (T12+40), respectively, and at temperatures lower than temperature T12, the correction reflection rate is set to have a predetermined slope so that the correction reflection rate is 40% at temperature T12, 20% at temperature (T12-10), 10% at temperature (T12-20), and zero at temperature (T12-40), respectively.

As for the correction reflection rate characteristic line L7', the correction reflection rate α at temperature T12 may be set to another value, such as 60% instead of 40%.

In this embodiment, the first oil temperature sensor 14 provided in the first oil passage 21 common to the multiple frictional engagement elements 10 is provided downstream of the pressure regulating valve 3 and upstream of the specified hydraulic circuit 4, but it may also be provided upstream of the pressure regulating valve 3 or in the specified hydraulic circuit 4. The automatic transmission 1 has six frictional engagement elements 10, but the oil temperature correction control is similarly applicable to automatic transmissions having multiple frictional engagement elements other than six.

In this way, the hydraulic control device 40 for the automatic transmission according to this embodiment is provided with a first oil temperature sensor 14 that detects the oil temperature of the first oil passage 21 common to the multiple frictional fastening elements 10, and multiple second oil temperature sensors 13 that detect the oil temperatures of the multiple second oil passages 22 that supply hydraulic pressure to the multiple frictional fastening elements 10, respectively, and the oil temperature detected by the first oil temperature sensor 14 is corrected by the oil temperature correction means 30 using the oil temperatures detected by the multiple second oil temperature sensors 13. Since the first oil temperature sensor 14 is learned and corrected using the multiple second oil temperature sensors 13, the detection accuracy of the first oil temperature sensor 14 can be improved, and the oil temperature of the automatic transmission can be detected with high accuracy.

As the first oil temperature sensor 14, a first oil temperature sensor 14 with improved accuracy is used by calibrating only the high temperature range above a predetermined temperature Ta such as 40 degrees, and the first oil temperature sensor 14 detects the oil temperature with high accuracy in the high temperature range, and in the low temperature range below the predetermined temperature Ta where the variation in the oil temperature detected by the second oil temperature sensor 13 is small, the oil temperature detected by the first oil temperature sensor 14 is learned and corrected using the oil temperatures detected by the multiple second oil temperature sensors 13, so that the oil temperature of the automatic transmission can be detected with high accuracy in the low temperature range and the high temperature range. The oil temperature of the automatic transmission can be detected with high accuracy without using an expensive, high-precision oil temperature sensor as the first oil temperature sensor, which is calibrated in the high temperature range and the low temperature range respectively to improve accuracy over the entire temperature range.

Therefore, in an automatic transmission 1 in which hydraulic pressure from the oil pump 2 is supplied to each of a plurality of frictional fastening elements 10, the oil temperature of the automatic transmission can be detected with high accuracy while suppressing increases in costs compared to when the oil temperature is detected using only the first oil temperature sensor.

The oil temperature correction means 30 also corrects the oil temperature when the oil temperatures detected by the second oil temperature sensors 13 are within a predetermined range. This makes it possible to improve the detection accuracy of the first oil temperature sensor 14 by using the oil temperatures detected by the second oil temperature sensors 13 when the oil temperatures detected by the second oil temperature sensors 13 are low and within a predetermined range with little variation, such as after a predetermined time has elapsed since the engine was stopped.

The oil temperature correction means 30 also corrects the oil temperature detected by the first oil temperature sensor 14 based on the average value of the oil temperatures detected by the first oil temperature sensor 14 and the multiple second oil temperature sensors 13. This makes it relatively easy to improve the detection accuracy of the first oil temperature sensor 14.

In addition, multiple oil pressure sensors 12 are provided to detect the oil pressure of the second oil passage 22, and the second oil temperature sensor 13 is provided integrally with the oil pressure sensor 12. This allows the oil temperature sensor 13 provided integrally with the oil pressure sensor 12 to be used as the second oil temperature sensor 13, and improves the accuracy of oil temperature detection by the first oil temperature sensor 14 while suppressing increases in costs without providing a separate second oil temperature sensor.

The oil temperature detected by the first oil temperature sensor 14 is also used to calculate the flow rate of hydraulic oil to be supplied to each of the multiple frictional fastening elements 10. As a result, when the flow rate of hydraulic oil to be supplied to each of the multiple frictional fastening elements 10 is calculated using the oil temperature to control the hydraulic pressure to be supplied to each of the multiple frictional fastening elements 10, the oil temperature can be detected with high accuracy and the hydraulic pressure to be supplied to each of the multiple frictional fastening elements 10 can be controlled with high accuracy.

The first oil temperature sensor 14 is also configured to be more accurate in the high temperature range above the predetermined temperature Ta than in the low temperature range below the predetermined temperature Ta. This makes it possible to suppress increases in costs compared to using an expensive oil temperature sensor that is calibrated separately for the high temperature range and the low temperature range to increase accuracy across the entire temperature range.

In the embodiment described above, in a vehicle equipped with an automatic transmission 1, normal oil temperature correction is performed after initial oil temperature correction, but it is also possible to perform normal oil temperature correction from the time the oil temperature detected by the first oil temperature sensor 14 is corrected for the first time without performing initial oil temperature correction.

The present invention is not limited to the illustrated embodiments, and various improvements and design changes are possible without departing from the spirit of the present invention.

As described above, according to the present invention, in an automatic transmission in which hydraulic pressure from an oil pump is supplied to each of a number of frictional fastening elements, it is possible to accurately detect the oil temperature of the automatic transmission while suppressing increases in costs, and therefore the present invention may be suitably used in the manufacturing industry of automatic transmissions or vehicles equipped with such transmissions.

Reference Signs List 1 Automatic transmission 2 Oil pump 10 Frictional engagement element 12 Oil pressure sensor 13 Second oil temperature sensor 14 First oil temperature sensor 20 Oil pressure control circuit 21 First oil passage 22 Second oil passage 30 Control unit 40 Oil pressure control device

Claims (6)

A hydraulic control device for an automatic transmission that supplies hydraulic pressure from an oil pump to a plurality of frictional engagement elements through a first oil passage common to the plurality of frictional engagement elements and a plurality of second oil passages branched from the first oil passage,
a first oil temperature sensor that detects an oil temperature in the first oil passage;
a plurality of second oil temperature sensors each detecting an oil temperature of the second oil passages;
and an oil temperature correction means for correcting the oil temperature detected by the first oil temperature sensor using the oil temperatures detected by each of the plurality of second oil temperature sensors. the oil temperature correction means corrects the oil temperature when the oil temperatures detected by each of the second oil temperature sensors are within a predetermined range.
2. The hydraulic control device for an automatic transmission according to claim 1. The oil temperature correction means corrects the oil temperature detected by the first oil temperature sensor based on an average value of the oil temperatures detected by the first oil temperature sensor and the plurality of second oil temperature sensors.
3. A hydraulic control device for an automatic transmission according to claim 1 or 2. a plurality of hydraulic pressure sensors each detecting an hydraulic pressure in the second oil passage;
The second oil temperature sensor is integrally provided with the oil pressure sensor.
The hydraulic control device for an automatic transmission according to any one of claims 1 to 3. The oil temperature detected by the first oil temperature sensor is used to calculate a flow rate of hydraulic oil to be supplied to each of the plurality of frictional engagement elements.
The hydraulic control device for an automatic transmission according to any one of claims 1 to 4. The first oil temperature sensor is configured to have higher accuracy in a high temperature range equal to or higher than a predetermined temperature range than in a low temperature range below the predetermined temperature.
The hydraulic control device for an automatic transmission according to any one of claims 1 to 5.

Images