Hydraulic control device for automatic transmission

Abstract

To accurately detect the oil temperature of an automatic transmission while suppressing an increase in cost.SOLUTION: A hydraulic control device of an automatic transmission 1 for supplying hydraulic pressure from an oil pump 2 to a plurality of friction fastening elements 10 through a first oil path 21 common to the plurality of friction fastening elements 10 and a plurality of second oil paths 22 branched from the first oil path 21 comprises: a first oil temperature sensor 14 for detecting the oil temperature of the first oil path 21; a plurality of second oil temperature sensors 13 for detecting the oil temperatures of the plurality of second oil paths 22; and oil temperature correction means 30 for correcting the oil temperature which is detected by the first oil temperature sensor 14 by using the oil temperatures which are detected by the plurality of second oil temperature sensors 13.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a hydraulic control device for an automatic transmission mounted on a vehicle. [Background technology]

[0002] An automatic transmission mounted on a vehicle generally includes a plurality of planetary gear sets (planetary gear mechanisms) and a plurality of frictional engagement elements such as clutches, brakes, etc. This type of automatic transmission is configured to selectively engage the plurality of frictional engagement elements to selectively switch the power transmission path passing through each planetary gear set, thereby achieving a gear shift stage according to the driving state of the vehicle.

[0003] A frictional fastening element of an automatic transmission includes a plurality of friction plates, a piston that presses the plurality of friction plates to fasten them together, and a hydraulic chamber to which hydraulic oil is supplied to urge the piston in the fastening direction, and is adapted to be fastened or released by supplying or discharging the hydraulic pressure of the hydraulic oil to or from the hydraulic chamber.

[0004] The hydraulic pressure of the working oil generated by the oil pump is supplied to each of the hydraulic chambers of the multiple frictional engagement elements through a first oil passage common to the multiple frictional engagement elements connected to the oil pump and a second oil passage branching off from the first oil passage and connected to each frictional engagement element. The hydraulic pressure supplied to the frictional engagement elements is controlled so as to suppress shocks and improve responsiveness when the frictional engagement elements are engaged.

[0005] The properties of the hydraulic oil supplied to the hydraulic chamber of the frictional fastening element, such as viscosity, change according to the oil temperature. For this reason, an oil temperature sensor that detects the oil temperature is provided in the automatic transmission, and the hydraulic pressure is controlled according to the oil temperature detected by the oil temperature sensor. To ensure that the oil temperature of the automatic transmission is at an appropriate temperature, an abnormality determination device for the oil temperature sensor that determines an abnormality in the oil temperature sensor is also known (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2010-180927 A Summary of the Invention [Problem to be solved by the invention]

[0007] 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 is disposed 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 is calculated in accordance with the oil temperature to control the hydraulic pressure. In such a case, 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.

[0008] In response to this, it is conceivable to use a high-precision oil temperature sensor that has improved accuracy over the entire temperature range instead of a normal oil temperature sensor, however, using a high-precision oil temperature sensor that has improved accuracy over the entire temperature range may result in increased costs.

[0009] Therefore, an object of the present invention is to provide a hydraulic control device for an automatic transmission that supplies hydraulic pressure from an oil pump to each of a plurality of frictional fastening elements, and that can accurately detect the oil temperature of the automatic transmission while suppressing increases in costs. [Means for solving the problem]

[0010] The present invention provides a hydraulic control device for an automatic transmission that supplies hydraulic pressure from an oil pump to each of 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, the hydraulic control device comprising: a first oil temperature sensor that detects the oil temperature of the first oil passage; a plurality of second oil temperature sensors that detect the oil temperatures of 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 each of the plurality of second oil temperature sensors.

[0011] According to the present invention, a first oil temperature sensor that detects the oil temperature in a first oil passage common to a plurality of frictional fastening elements and a plurality of second oil temperature sensors that detect the oil temperatures in a plurality of second oil passages that supply hydraulic pressure to the plurality of frictional fastening elements respectively are provided, and the oil temperature detected by the first oil temperature sensor is corrected by the oil temperature correction means 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.

[0012] 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 in the low temperature range and the high temperature range 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.

[0013] Therefore, in an automatic transmission in which oil pressure from an oil pump is supplied to each of 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.

[0014] It is preferable that the oil temperature correcting means corrects the oil temperature when the oil temperatures detected by each of the plurality of second oil temperature sensors are within a predetermined range.

[0015] With this configuration, the oil temperature is corrected when the oil temperatures detected by each of 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 after the engine is stopped, the detection accuracy of the first oil temperature sensor can be improved using the oil temperatures detected by the multiple second oil temperature sensors.

[0016] It is preferable that 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.

[0017] 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.

[0018] It is preferable that a plurality of oil pressure sensors are provided for detecting the oil pressure of the second oil passage respectively, and the second oil temperature sensor is provided integrally with the oil pressure sensor.

[0019] With this configuration, the second oil temperature sensor is integrally provided with the hydraulic pressure sensor that detects the hydraulic pressure in the second oil passage, so that the oil temperature sensor integrally provided with the hydraulic pressure sensor can be used as the second oil temperature sensor. This makes it possible to improve the accuracy of oil temperature detection by the first oil temperature sensor while suppressing increases in costs without having to provide a separate second oil temperature sensor.

[0020] 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 a plurality of frictional engagement elements.

[0021] 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.

[0022] The first oil temperature sensor is preferably configured to have higher accuracy in a high temperature range equal to or higher than a predetermined temperature than in a low temperature range below the predetermined temperature.

[0023] 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 reduced compared to using an expensive oil temperature sensor that is calibrated separately in the high and low temperature ranges to improve accuracy across the entire temperature range. Effect of the Invention

[0024] According to the hydraulic control device for an automatic transmission of the present invention, in an automatic transmission in which hydraulic pressure from an oil pump is supplied to each of a plurality of frictional engagement elements, it is possible to accurately detect the oil temperature of the automatic transmission while suppressing increases in costs. [Brief description of the drawings]

[0025] [Figure 1] 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; [Diagram 2] FIG. 4 is an explanatory diagram for explaining a tolerance of an oil temperature sensor. [Diagram 3] 1 is a block diagram showing a hydraulic control device for an automatic transmission; [Figure 4] FIG. 4 is a diagram showing a target correction temperature range of the oil temperature sensor. [Diagram 5] FIG. 11 is a diagram showing a target correction temperature characteristic used for initial oil temperature correction. [Figure 6] FIG. 4 is a diagram showing a target correction temperature characteristic and an execution correction temperature characteristic used in normal oil temperature correction. [Figure 7] FIG. 13 is a diagram showing a correction reflection characteristic. [Figure 8] 5 is a flowchart showing a temperature correction control for an oil temperature sensor. [Figure 9] FIG. 11 is another diagram showing the correction reflection characteristic. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0027] Fig. 1 is a circuit diagram showing a main part of a hydraulic control circuit of an automatic transmission according to an embodiment of the present invention. The automatic transmission according to the embodiment of the present invention is mounted on a vehicle such as a front engine / rear drive vehicle, and receives power from an engine, although the present invention is not limited thereto. The automatic transmission includes a transmission mechanism that includes a plurality of planetary gear sets and a plurality of frictional fastening elements such as clutches and brakes, located on the axis of an input shaft connected to the engine, in a transmission case.

[0028] The automatic transmission is configured to selectively switch the power transmission path through each planetary gear set by selectively engaging a plurality of frictional engagement elements that constitute the transmission mechanism, thereby achieving a gear stage according to the driving state of the vehicle. The automatic transmission has four planetary gear sets, five frictional engagement elements consisting of three clutches and two brakes, and is configured to achieve eight forward gears and a reverse gear by selectively engaging three of these frictional engagement elements.

[0029] The automatic transmission is connected to the engine without a fluid power transmission device such as a torque converter, and includes a power connecting / disconnecting clutch as a frictional fastening element between the engine and the input shaft of the automatic transmission. The power connecting / disconnecting clutch is configured to be capable of connecting and disconnecting the output shaft of the engine and the input shaft of the automatic transmission. When the power connecting / disconnecting clutch is engaged, power can be transmitted between the engine and the automatic transmission.

[0030] In an automatic transmission, a drive sprocket for driving an oil pump is connected to the output shaft of the engine and arranged coaxially between the engine and the power connecting / disconnecting clutch, and an oil pump arranged inside the transmission case and radially spaced from the axis of the automatic transmission is driven via a chain.

[0031] In this embodiment, the automatic transmission has six frictional engagement elements, consisting of five frictional engagement elements that constitute the speed change mechanism and a frictional engagement element that constitutes the power engagement / disengagement clutch. Each frictional engagement 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.

[0032] As shown in FIG. 1, the automatic transmission 1 has a hydraulic control circuit 20 that selectively supplies hydraulic pressure from an oil pump 2 to a plurality of frictional engagement elements 10, specifically, six frictional engagement elements 10, to transmit power from the engine to the automatic transmission 1 and to achieve a predetermined gear shift stage.

[0033] 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 each of 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.

[0034] 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 predetermined hydraulic pressure, as well as a predetermined hydraulic circuit 4 that includes a manual valve that switches the supply destination of the line pressure in accordance with the range selected by the driver, and a shift valve that switches the supply and discharge of hydraulic pressure to and from the multiple frictional engagement elements 10.

[0035] A solenoid valve 11 is provided in each of the second oil passages 22 to control the hydraulic pressure supplied to the frictional engagement elements 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 block communication between the source pressure port and the output port and communicate the output port with a drain port, thereby supplying and discharging the hydraulic pressure to be supplied to the frictional engagement elements 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.

[0036] An oil pressure sensor 12 that detects the oil pressure of the second oil passage 22 is disposed downstream of the solenoid valve 11 in the second oil passage 22. The oil pressure detected by the oil pressure sensor 12 is used for calculating the flow rate of hydraulic oil supplied to each frictional fastening element 10 and for hydraulic control 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 with the oil pressure sensor 12, and the oil pressure sensor 12 uses the oil temperature detected by the second oil temperature sensor 13 to monitor whether the temperature of the oil pressure sensor 12 has increased due to an overcurrent or the like.

[0037] The second oil temperature sensor 13, which is integrally provided with the oil pressure sensor 12, uses 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 specified range, such as ±1 degree, in the high temperature range above a specified temperature, such as 40 degrees, and in the low temperature range below the specified temperature.

[0038] In the automatic transmission 1, an oil temperature sensor (first oil temperature sensor) 14 that detects the oil temperature of 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 predetermined 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.

[0039] 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 the low temperature range below the predetermined temperature, but in the 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 degree.

[0040] Fig. 2 is an explanatory diagram explaining the tolerance of an oil temperature sensor. In Fig. 2, for the first oil temperature sensor 14, the horizontal axis represents temperature (°C) and the vertical axis represents the detection accuracy (°C), which is the tolerance of the oil temperature sensor. Compared to a normal oil temperature sensor that has an almost constant tolerance W1 regardless of temperature, as shown by the two-dot chain line L1 in Fig. 3, the first oil temperature sensor 14 is calibrated so that the tolerance W2 is equal to or less than a predetermined value in a high temperature range above a predetermined temperature Ta, such as 40 degrees, as shown by the solid line L2 in Fig. 3, and is configured to have high accuracy.

[0041] The first oil temperature sensor 14 is calibrated and configured to have high accuracy in the high temperature range, and therefore the tolerance W3 decreases as the temperature increases in the low temperature range below the desired temperature Ta, but is 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.

[0042] In the low temperature region 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 region, as shown by the dashed line L3 in Figure 3.

[0043] As described above, the oil temperature detected by the first oil temperature sensor 14 is used for calculating the flow rate of hydraulic oil supplied to each frictional engagement element 10, and is used for hydraulic control of each frictional engagement element 10, etc.

[0044] When calculating the flow rate of hydraulic oil to be supplied to each frictional engagement element 10, a differential pressure between an indicated pressure for a solenoid valve 11 provided in the second oil passage 22 and an oil pressure detected by an oil pressure sensor 12 provided in the second oil passage 22 is calculated, and the inflow flow rate of hydraulic oil to the hydraulic chamber of the frictional engagement element 10 is calculated using characteristic data indicating the relationship between the differential pressure and the inflow flow rate of hydraulic oil to the hydraulic chamber of the frictional engagement element 10, and an integrated flow rate of hydraulic oil to be supplied to the hydraulic chamber of the frictional engagement element 10 is calculated. A predicted oil pressure of the hydraulic chamber is then calculated from the calculated integrated flow rate of hydraulic oil to be supplied to the hydraulic chamber of the frictional engagement element 10, and the oil pressure supplied to the frictional engagement element 10 is controlled based on the predicted oil pressure.

[0045] The characteristic data indicating the relationship between the differential pressure and the inflow flow rate of hydraulic oil into the hydraulic chamber of the frictional engagement element 10 depends on the oil temperature of the hydraulic oil, and is set so that the higher the oil temperature, the larger the inflow flow rate becomes and the lower the oil temperature becomes. The flow rate of hydraulic oil to be supplied to each frictional engagement element 10 is calculated using the characteristic data corresponding to the oil temperature detected by the first oil temperature sensor 14. The calculation of the flow rate of hydraulic oil to be supplied to each frictional engagement element 10 is performed by the control unit 30.

[0046] The control unit 30 corrects the oil temperature detected by the first oil temperature sensor 14 using the oil temperatures detected by each of the multiple second oil temperature sensors 13, so as to improve the detection accuracy of the oil temperature detected by the first oil temperature sensor 14.

[0047] Fig. 3 is a block diagram showing a hydraulic control device for an automatic transmission. As shown in Fig. 3, a hydraulic control device 40 for an automatic transmission includes a control unit 30 that controls each solenoid valve 11 in a hydraulic control circuit 20 to form a gear stage according to the driving state.

[0048] The control unit 30 receives inputs of a range sensor 5 which detects the range selected by the driver's operation, a vehicle speed sensor 6 which detects the vehicle speed, an accelerator opening sensor 7 which detects the amount of depression of the accelerator pedal by the driver (accelerator opening), a plurality of oil pressure sensors 12 which detect the oil pressure supplied to each of a plurality of frictional fastening elements, a first oil temperature sensor 14 which detects the oil temperature in the first oil passage 21, a plurality of second oil temperature sensors 13 which detect the oil temperatures in each of the plurality of second oil passages 22, an engine speed sensor (not shown) which detects the engine speed, and signals from a soak timer (not shown) which detects the soak time, which is the time elapsed since the engine was stopped.

[0049] 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, other solenoid valves included in the predetermined hydraulic circuit 4, and the like, depending on the operating conditions, and selectively supplies hydraulic pressure from the oil pump 2 to each of the six frictional engagement elements 10, thereby transmitting power from the engine to the automatic transmission 1 and forming a predetermined gear stage depending on the operating conditions. The control unit 30 is mainly constituted by a microcomputer.

[0050] As described above, the control unit 30 calculates the flow rate of hydraulic oil to be supplied to each of the multiple frictional fastening elements 10 based on the oil temperature detected by the first oil temperature sensor 14, based on various signals, and controls the oil pressure to be supplied to the hydraulic chamber of each frictional fastening element 10 based on the calculated flow rate of hydraulic oil.

[0051] The control unit 30 is also configured to correct 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 oil pressure with high accuracy. 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.

[0052] The first oil temperature sensor 14 and the second oil temperature sensor 13 are each configured to detect oil temperature and include a detection unit that detects 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.

[0053] The second oil temperature sensor 13 is configured so that its detection accuracy is within a first predetermined range, such as ±1 degree, in a high temperature range above a predetermined temperature, such as 40 degrees, and 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 a predetermined temperature, such as 40 degrees, but its accuracy is increased so that its detection accuracy is within a second predetermined range, such as ±0.5 degree, which is smaller than the first predetermined range, in a high temperature range above the predetermined temperature. 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.

[0054] Fig. 4 is a diagram showing the target correction temperature range of the oil temperature sensor. In Fig. 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.

[0055] As shown in Figure 4, the upper limit line L4 is set to 6 degrees when the temperature is between -30 degrees and -20 degrees, and is set to have a predetermined slope where the temperature is between -20 degrees and 4 degrees when the temperature is between -20 degrees and 40 degrees, and is set to have a predetermined slope where the temperature is between 40 degrees and 110 degrees, becoming 4 degrees at 40 degrees and zero at 110 degrees.

[0056] The lower limit line L5 is set to -6 degrees when the temperature is between -30 degrees and -20 degrees, and is set to have a predetermined slope such that when the temperature is between -20 degrees and 40 degrees, it becomes -6 degrees at -20 degrees and -4 degrees at 40 degrees, and when the temperature is between 40 degrees and 110 degrees, it becomes -4 degrees at 40 degrees and zero at 110 degrees.

[0057] When 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 when it is higher than the upper limit line L4, it is set to the target correction temperature of the upper limit line L4, and when 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, when the measured temperature is 20 degrees and the target correction temperature P1 is 2 degrees, the target correction temperature is set to 2 degrees, but when the measured temperature is 40 degrees and the target correction temperature P2 is 6 degrees, it is set to 4 degrees, which is the target correction temperature P3 of the upper limit line L4.

[0058] In this way, when the target correction temperature for the measured temperature is set, by setting it within the target correction temperature range, it is possible to prevent the target correction temperature from being set erroneously due to a malfunction of the oil temperature sensor, for example.

[0059] 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 multiple second oil temperature sensors 13.

[0060] 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 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.

[0061] Next, an oil temperature error of the average oil temperature of the calculated first and second oil temperatures 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 and second oil temperatures and the first oil temperature is calculated as the oil temperature error. Then, 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.

[0062] 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.

[0063] Fig. 5 is a diagram showing the target correction temperature characteristic used for initial oil temperature correction. In Fig. 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 the automatic transmission 1, the target correction temperature characteristic line L6 shown in Fig. 5 is used.

[0064] For the target correction temperature characteristic line L6, the target correction temperature T21 is set by multiplying the oil temperature error by (-1) 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.

[0065] The target correction temperature characteristic line L6 is set for temperatures from -30 degrees to 110 degrees so that at temperatures higher than temperature T11, it connects the target correction temperature T21 at temperature T11 with the target correction temperature which is 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.

[0066] Once the target correction temperature characteristic line L6 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. 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 effective correction temperature characteristic.

[0067] Once the effective correction temperature characteristic is calculated, the output section of first oil temperature sensor 14 is controlled to correct the oil temperature detected by first oil temperature sensor 14 using the effective correction temperature characteristic and output the corrected oil temperature. The next time the oil temperature is detected by first oil temperature sensor 14, first oil temperature sensor 14 corrects the oil temperature detected by the sensor section and the measurement circuit section using the effective correction temperature characteristic, i.e., corrects the oil temperature by adding the target correction temperature, and outputs the corrected oil temperature.

[0068] Fig. 6 is a diagram showing the target correction temperature characteristic and the execution correction temperature characteristic used in normal oil temperature correction. In Fig. 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 Fig. 6 is used.

[0069] As with the target correction temperature characteristic line L6, the target correction temperature characteristic line L7 is set such that, at the oil temperature T12 detected by the first oil temperature sensor 14, the oil temperature error is multiplied by (-1) to set a target correction temperature T22.

[0070] 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 which is zero at temperature (T12+40) degrees, and has a predetermined slope such 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 which is zero at temperature (T12-40) degrees, and has a predetermined slope such that the target correction temperature decreases as the temperature decreases.

[0071] Regarding normal oil temperature correction, once the target correction temperature characteristic line L7 is calculated, an effective correction temperature characteristic that actually reflects the target correction temperature characteristic when correcting the oil temperature detected by the first oil temperature sensor 14 is calculated.

[0072] Fig. 7 is a diagram showing the correction reflection characteristic. In Fig. 7, the horizontal axis represents the measured temperature, and the vertical axis represents the correction reflection rate, showing the correction reflection characteristic used in 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 (T12-40) to (T12+40) regardless of temperature, and in normal oil temperature correction, a correction reflection characteristic line L8 as shown in Fig. 7 is used.

[0073] The correction reflection characteristic line L8 is set so that, for temperatures from (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 which 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 which is zero at temperature (T12-40) degrees, and the correction reflection rate decreases as the temperature decreases.

[0074] 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.

[0075] 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, for temperatures from (T12-40) to (T12+40), and is set to have a predetermined slope connecting the execution correction temperature αT22 at temperature T12 and the execution correction temperature which is zero at temperature (T12+40) degrees, so that the execution correction temperature decreases as the temperature increases, at temperatures higher than temperature T12, and is set to have a predetermined slope connecting the execution correction temperature αT22 at temperature T12 and the execution correction temperature which is zero at temperature (T12-40) degrees, so that the execution correction temperature decreases as the temperature decreases, at temperatures lower than temperature T12.

[0076] For normal oil temperature correction, once the effective correction temperature characteristics are calculated, the output section of first oil temperature sensor 14 is controlled to correct the oil temperature detected by first oil temperature sensor 14 using the effective correction temperature characteristics and output the corrected oil temperature. The next time the oil temperature is detected by first oil temperature sensor 14, first oil temperature sensor 14 corrects the oil temperature detected by the sensor section and measurement circuit section using the effective correction temperature characteristics, i.e., corrects the oil temperature by adding the target correction temperature, and outputs the corrected oil temperature.

[0077] 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 that the oil temperature detected by the first oil temperature sensor 14 can be detected with high accuracy.

[0078] 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.

[0079] 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 FIG. 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.

[0080] First, various signals are read into the control unit 30 (step S1). Signals from the range sensor 5, the vehicle speed sensor 6, the accelerator opening sensor 7, the plurality of oil pressure sensors 12, the first oil temperature sensor 14, the plurality of second oil temperature sensors 13, the engine speed sensor, and the soak timer are read.

[0081] 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 the 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.

[0082] 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, with respect 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.

[0083] If the determination result in step S3 is YES, an 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).

[0084] 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). As the target correction temperature characteristic, in the initial oil temperature correction, a target correction temperature characteristic line L6 as shown in FIG.

[0085] After 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 it is as the effective correction temperature characteristic.

[0086] When the effective correction temperature characteristic is calculated in step S6, correction control of the oil temperature detected by first oil temperature sensor 14 is executed based on the calculated effective correction temperature characteristic (step S7), and the process ends. The next time the oil temperature is detected by first oil temperature sensor 14, the oil temperature detected by first oil temperature sensor 14 is corrected using the effective correction temperature characteristic and output.

[0087] The output section of first oil temperature sensor 14 is configured to correct the oil temperature detected by first oil temperature sensor 14 using the effective correction temperature characteristics and output the oil temperature detected by first oil temperature sensor 14 the next time the oil temperature is detected by first oil temperature sensor 14. Similarly, the output section of first oil temperature sensor 14 is also configured to correct the oil temperature detected by first oil temperature sensor 14 using the effective correction temperature characteristics and output the oil temperature for normal oil temperature correction performed after initial oil temperature correction.

[0088] When the target correction temperature characteristic is calculated in step S5, in the normal oil temperature correction, a target correction temperature characteristic line L7 as shown by a solid line in FIG. 6 is calculated.

[0089] 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 reflecting 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 reflecting characteristic, and an effective correction temperature characteristic line L9 as shown by the two-dot chain line in Fig. 6 is calculated.

[0090] For normal oil temperature correction, once the effective correction temperature characteristic is calculated in step S6, correction control of the oil temperature detected by first oil temperature sensor 14 is executed based on the calculated effective correction temperature characteristic (step S7), and the process ends. The next time the oil temperature is detected by first oil temperature sensor 14, the oil temperature detected by first oil temperature sensor 14 is corrected using the effective correction temperature characteristic and output.

[0091] 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.

[0092] 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 eight hours, has not elapsed since the engine was stopped, the oil temperatures detected by the multiple second oil temperature sensors 13 may be high and have large variations in oil temperature, so oil temperature correction control is not performed.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] As described above, the oil temperature detected in this manner by the first oil temperature sensor 14 is used for calculating the flow rate of hydraulic oil to be supplied to each of the multiple frictional fastening elements 10, and the calculation of the flow rate of hydraulic oil, etc. can be performed with high accuracy.

[0097] In this embodiment, it is determined whether a predetermined time, such as 8 hours, has elapsed after the engine is stopped. However, experiments etc. have shown that when 8 hours have elapsed after the engine is stopped, the oil temperatures detected by each of the multiple second oil temperature sensors 13 are within 0.5 degrees. Therefore, instead of determining whether a predetermined time has elapsed after the engine is stopped, it may be determined whether the oil temperatures detected by each of the multiple second oil temperature sensors 13 are within a predetermined range, such as 0.5 degrees.

[0098] Furthermore, when the oil temperature error is calculated, the average oil temperature of all the 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.

[0099] In addition, in the output section of the first oil temperature sensor 14, the oil temperature detected by the first oil temperature sensor 14 is corrected by the effective correction temperature characteristic and output, but the oil temperature detected by the first oil temperature sensor 14 may also be corrected by the control unit 30 by the effective correction temperature characteristic and output.

[0100] Furthermore, in normal oil temperature correction, when the target correction temperature characteristic is calculated, if the target correction temperature characteristic as shown in FIG. 6 is outside the target correction temperature range shown in FIG. 4, it is corrected to be within the target correction temperature range and calculated; however, it is also possible to calculate the target correction temperature characteristic without setting the target correction temperature range.

[0101] In this embodiment, when the execution correction temperature characteristic is calculated, the normal oil temperature correction uses the correction reflection characteristic line L8 as shown in FIG. 7, but the correction reflection rate α at the temperature T12 may be set to another value such as 60% instead of 40%.

[0102] Fig. 9 is another diagram showing the correction reflection characteristic. Instead of the correction reflection characteristic line L8 as shown in Fig. 7, a correction reflection characteristic line L7' as shown in Fig. 9 may be used to calculate the effective correction temperature characteristic.

[0103] The correction reflection characteristic line L7' is set to have a predetermined slope such that, 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 40% at temperature T12, the correction reflection rate is 20% at temperature (T12+10), the correction reflection rate is 10% at temperature (T12+20), and the correction reflection rate is zero at temperature (T12+40), and at temperatures lower than temperature T12, the correction reflection rate is set to have a predetermined slope such that the correction reflection rate is 40% at temperature T12, the correction reflection rate is 20% at temperature (T12-10), the correction reflection rate is 10% at temperature (T12-20), and the correction reflection rate is zero at temperature (T12-40).

[0104] Regarding the correction reflection rate characteristic line L7', the correction reflection rate α at the temperature T12 may be set to another value such as 60% instead of 40%.

[0105] 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 a number of frictional engagement elements other than six.

[0106] As described above, 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 in the first oil passage 21 common to the multiple frictional engagement elements 10, and multiple second oil temperature sensors 13 that detect the oil temperatures in the multiple second oil passages 22 that supply hydraulic pressure to the multiple frictional engagement 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.

[0107] As the first oil temperature sensor 14, a first oil temperature sensor 14 with improved accuracy calibrated only in the high temperature range above a predetermined temperature Ta such as 40 degrees is used, and the oil temperature is accurately detected by the first oil temperature sensor 14 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, 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.

[0108] Therefore, in an automatic transmission 1 that supplies hydraulic pressure from an oil pump 2 to each of multiple frictional fastening elements 10, the oil temperature of the automatic transmission can be detected with high accuracy while suppressing increases in costs compared to a case in which the oil temperature is detected using only the first oil temperature sensor.

[0109] Furthermore, the oil temperature correction means 30 corrects the oil temperature when the oil temperatures detected by each of the multiple 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 multiple second oil temperature sensors 13 when the oil temperatures detected by the multiple second oil temperature sensors 13 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.

[0110] Furthermore, the oil temperature correction means 30 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 possible to improve the detection accuracy of the first oil temperature sensor 14 relatively easily.

[0111] Further, a plurality of oil pressure sensors 12 are provided for detecting 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 the accuracy of detecting the oil temperature by the first oil temperature sensor 14 can be improved while suppressing an increase in costs without providing a separate second oil temperature sensor.

[0112] Furthermore, the oil temperature detected by the first oil temperature sensor 14 is used to calculate the flow rate of hydraulic oil to be supplied to each of the multiple frictional engagement elements 10. As a result, when the flow rate of hydraulic oil to be supplied to each of the multiple frictional engagement elements 10 is calculated using the oil temperature to control the hydraulic pressure to be supplied to each of the multiple frictional engagement elements 10, the oil temperature can be detected with high accuracy and the hydraulic pressure to be supplied to each of the multiple frictional engagement elements 10 can be controlled with high accuracy.

[0113] The first oil temperature sensor 14 is also configured to be more accurate in a high temperature range equal to or higher than a predetermined temperature Ta than in a 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 improve accuracy over the entire temperature range.

[0114] 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.

[0115] The present invention is not limited to the exemplified embodiments, and various improvements and design modifications are possible without departing from the gist of the present invention. [Industrial Applicability]

[0116] 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 plurality 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 industrial manufacturing field of automatic transmissions or vehicles equipped with such transmissions. [Explanation of symbols]

[0117] 1 Automatic transmission 2 Oil pump 10 Frictional Fastening Elements 12 Oil Pressure Sensor 13 No. 2 Oil Temperature Sensor 14 No. 1 Oil Temperature Sensor 20 Hydraulic control circuit 21 No. 1 oil road 22 2nd oilway 30 Control Unit 40 Hydraulic control device

Claims

1. 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.

2. 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.

3. 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.

4. 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.

5. 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.

6. 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.

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