JP2991062B2 - Oil temperature detection device using solenoid valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting oil temperature in an automatic transmission for a vehicle, and more particularly to a device for detecting oil temperature based on a resistance value of a solenoid valve.

[0002]

2. Description of the Related Art As is well known, an automatic transmission for a vehicle is controlled by a hydraulic pressure.
Because of the complicated oil passages, the large number of orifices, and the valves, the viscosity of the oil greatly affects the supply / discharge characteristics of the hydraulic pressure and, consequently, the shift characteristics. Normally, the hydraulic control device is configured to be suitable for a commonly used oil temperature, so if, for example, the oil temperature is low, the supply and discharge of the hydraulic pressure will be delayed. In order to prevent a shift shock or a shift delay caused by the change, it is desired to accurately detect the oil temperature and control the valve switching timing and the like in accordance with the temperature.

In order to detect the temperature of the oil of the automatic transmission, it is conceivable to provide a sensor at an appropriate position in an oil pan or an oil passage. However, if a sensor for detecting the oil temperature is specially provided. If this is the case, the number of parts will increase, and the weight and cost will increase accordingly. Therefore, in order to avoid such inconvenience and detect the oil temperature, attention may be paid to the fact that the resistance value of the coil of the solenoid valve is substantially proportional to the temperature, and the oil temperature may be detected from the resistance value.
As one example, JP-A-3-249964 discloses that
A device that detects the resistance value of the solenoid coil in the flow control valve of the paint supply device, determines that the temperature of the solenoid coil has reached the upper limit temperature due to the resistance value having reached the upper limit value, and stops the energization is described. I have.

[0004]

The hydraulic circuit in the automatic transmission is also provided with a solenoid valve for controlling the oil pressure in accordance with the state of energization of the coil, and therefore, based on the resistance of the coil of the solenoid valve. Oil temperature can be detected.
However, since the solenoid valve operates the plunger by electromagnetic force to control the hydraulic pressure, the internal resistance-temperature characteristics of the coil are proportional even if the resistance value of the coil is proportional to the temperature. Fluctuation is large, and the detection accuracy of the oil temperature may not always be sufficient.

[0005] The position of the solenoid valve in the hydraulic circuit is determined by the configuration of the oil passage and restrictions on space, and is not always the position that best reflects the oil temperature of the entire hydraulic circuit. Therefore, even if the internal resistance of the solenoid valve reflects the oil temperature well, it may be the oil temperature at a limited portion, and the difference from the oil temperature required as control data is likely to be large.

The present invention has been made in view of the above circumstances, and has as its object to provide a device capable of detecting oil temperature more accurately by utilizing the resistance value of a coil of a solenoid valve. It is.

[0007]

According to the present invention, in order to achieve the above-mentioned object, the configuration shown in FIG. 1 is adopted. That is, the present invention provides a solenoid valve 3 for controlling the hydraulic pressure in the hydraulic circuit 2 according to the state of energization of the coil 1.
A temperature detecting means 4 for detecting a temperature other than the hydraulic circuit 2 using an electromagnetic valve for detecting an oil temperature based on a resistance value of the coil 1; And a correcting means 5 for correcting a temperature characteristic value with respect to the resistance value based on a temperature other than the hydraulic circuit 2.

Further, in the present invention, there is further provided estimating means 6 for estimating that the temperature other than the hydraulic circuit 2 is substantially equal to the temperature of the oil in the hydraulic circuit 2, and the correcting means 5 comprises: When it is estimated that the temperature other than the hydraulic circuit 2 and the oil temperature are substantially equal, the temperature characteristic value with respect to the resistance value of the coil 1 may be corrected based on the temperature other than the hydraulic circuit 2.

[0009]

According to the present invention, basically, the resistance value of the coil 1 of the solenoid valve 3 is detected, and the oil temperature is obtained based on the detected value. In this case, the temperature other than the hydraulic circuit 2 is also detected by the temperature detecting means 4, and the resistance-temperature characteristics of the coil 1 are corrected based on the detected temperature. The correction method is, for example, increasing or decreasing the detected resistance value based on the detected temperature, or a temperature corresponding to the resistance value,
There is a method of increasing / decreasing based on the detected temperature. Therefore, the temperature obtained from the corrected characteristics substantially matches the actual temperature, and accurate temperature detection can be performed.

The correction of the resistance-temperature characteristics based on the temperature other than the hydraulic circuit 2 is performed when the estimating means 6 estimates that the temperature other than the hydraulic circuit 2 is equal to the oil temperature of the hydraulic circuit 2. By doing so, more accurate correction becomes possible.

[0011]

Next, the present invention will be described based on embodiments. FIG. 2 shows a linear solenoid valve 10 that outputs a hydraulic pressure proportional to an input signal, and a coil 12 is arranged on an outer peripheral side of a core 11. The pin 13 is inserted so as to move back and forth in the axial direction along the central axis of the core 11. One end of the pin 13 is attached to a plunger 14 arranged so as to face the end of the coil 12. In FIG. 2, reference numeral 15 indicates a case, and reference numeral 16 indicates a cover.

A sleeve 17 is connected to an end of the core 11 opposite to the plunger 14, and a spool 18 is inserted therein so as to be movable in the axial direction. The pin 13
A spring 19 is arranged at an end opposite to the above.
That is, an axial force based on the electromagnetic force via the pin 13 and an axial force based on the elastic force of the spring 19 act on the spool 18. further,
An input port 20, an output port 21, and a drain port 22 are formed in the sleeve 17, and the spool 18 is made to act on the spool 18 in the same direction as the spring 19 using the output pressure as a feedback pressure. Therefore, in the linear solenoid valve 10 shown in FIG. 2, the load of the pin 13 pressing the spool 18 in the axial direction changes according to the energized state of the coil 12, and as a result, the pressure regulation level changes and the output pressure changes from the output port 21. The output hydraulic pressure is adjusted to a pressure according to the state of energization of the coil 12.

FIG. 3 shows the linear solenoid valve 10 described above.
Is shown, and the coil 12 is connected between the transistor 24 and the resistor 25 in series with them. The other terminal of the transistor 24 is connected to a power supply of a predetermined voltage Vb.
Is grounded. And transistor 2
4 is a central processing unit (CPU) 26 of the automatic transmission.
, A duty signal is input, and the energization of the coil 12 is controlled by turning on / off the transistor 24 by the duty signal.
The resistor 25 is a resistor for current detection. The average voltage Vi applied to both ends of the resistor 25 and the power supply voltage Vb are input to an A / D converter 27, where the A / D The converted signal is input to the CPU 26. Therefore, the resistance value Rs of the coil 12
Is given by Rs = Ri × {(Vb−Vi) / Vi} where Ri is the resistance value of the resistor 25.

FIG. 4 is a flowchart for explaining the oil temperature detecting process according to the present invention.
The correction routine shown in FIG. After performing the initial setting, it is determined whether or not the ignition switch of the engine (E / G) has been switched from OFF to ON (step 1). Exit. If it is detected that the ignition switch has been switched from OFF to ON, it is determined whether or not the engine stop time is equal to or longer than a predetermined time α (step 2). If α has not been reached, this routine is exited without performing any particular control. If it is determined that the engine has been stopped for the predetermined time α or more, the process proceeds to step 3 to correct the resistance value.

Step 2 is a control corresponding to the estimating means in the present invention. If the stop time of the engine is equal to or longer than a predetermined time α, the engine, the automatic transmission connected thereto and the automatic transmission thereof are automatically controlled. This means that the temperatures of the hydraulic circuit and the like for controlling the transmission are substantially equal. In other words, the time α used as a criterion here is a time until the temperature of the engine, the automatic transmission, the hydraulic circuit for the automatic transmission, and the like becomes substantially equal.

In step 3, a correction value Rsa of the resistance value is obtained from the detected resistance value Rs and the engine coolant temperature Tw.
That is, the engine coolant temperature Tw is constantly detected, and is substantially equal to the oil temperature in the hydraulic circuit. Therefore, a resistance value corresponding to the engine coolant temperature Tw is obtained from a map (characteristic diagram) showing a correlation between the resistance value of the coil 12 and the temperature. In FIG. 4A, this is indicated by M ^-1 (TW). That is, a resistance value-temperature characteristic diagram of the used linear solenoid valve 10 is, for example, as shown in FIG. 5, and the resistance value is obtained from the temperature using this. On the other hand, the resistance value Rs of the coil 12 at that time is
Is detected in the above-described electric circuit shown in FIG. 3, and a resistance value based on the engine coolant temperature Tw is subtracted from the detected resistance value Rs to obtain a correction value Rsa. Then, the correction value Rsa is stored in the nonvolatile memory (step 4).

The correlation between the resistance value of the coil 12 and the temperature in the above-described linear solenoid valve 10 is obtained by performing an inspection in advance, and this can be mapped and stored. Therefore, the correction value Rsa obtained as described above is replaced with the actually detected resistance value Rs.
From the resistance value corrected in this manner and the resistance-temperature map shown in FIG. This is shown in the flowchart of FIG. In step 10 shown in FIG. 4B, the oil temperature Ts based on the current resistance value indicates that the oil temperature is obtained from the map based on a value obtained by subtracting the correction value Rsa from the actually measured resistance value Rs. .

Therefore, according to the oil temperature detecting means shown in FIG. 4, since the engine stop time is equal to or longer than the predetermined time α, the oil temperature is actually detected when the oil temperature and the engine water temperature become substantially equal. Engine temperature T
The resistance value of the coil 12 is corrected so as to correspond to w, and the correction width (correction amount) Rsa is set to the linear solenoid valve 10.
Then, the measured value of the resistance value thereafter is corrected by the correction amount Rsa, and the oil temperature is detected. Therefore, since the correction value corresponds to the actual measurement, the obtained oil temperature Ts becomes a value excluding the influence of the individual difference of the solenoid valve 10 and the influence of its installation position, and accurate oil temperature detection becomes possible.

Incidentally, the hydraulic control device of the automatic transmission includes:
Usually, a plurality of solenoid valves are provided, and the installation positions of the solenoid valves are different from each other, so that the frequency of supply / discharge of hydraulic pressure or the frequency of contact with oil is different. Further, the resistance value-temperature characteristics of these solenoid valves are not always in a uniform tendency, and there are many cases where the variation among individuals varies. Therefore, when detecting the oil temperature from the resistance value of the coil of the solenoid valve, the detection value may be corrected by averaging the characteristics based on the detection values of the plurality of solenoid valves.

To explain a specific example, when three solenoid valves are used, the temperature is detected based on the resistance value of the coil of each solenoid valve. These values are temporarily set as Ts1, Ts2, and Ts3. On the other hand, error amounts ΔT1, ΔT2, and ΔT3 of the detected temperatures caused by variations in the resistance values of the coils of the solenoid valves are obtained.
For example, this is obtained by assembling these solenoid valves in a hydraulic control device having the same configuration as that of the actual machine, and determining the difference between the temperature obtained from the resistance value of the coil of these solenoid valves and the actually measured oil temperature at the location to be obtained. Therefore, the error amounts ΔT1, ΔT2, and ΔT3 are values including an error amount based on the individual difference of each solenoid valve and an error amount based on the arrangement position. The equation for calculating the oil temperature based on the detected temperature and the error amount is shown by equation (1).

[0021]

(Equation 1) Therefore, if the characteristics of a plurality of solenoid valves are combined and corrected as described above, the difference from the actual oil temperature when the oil temperature is detected based on the resistance value of a specific solenoid valve is measured. The error is reduced, and as a result, the accuracy of detecting the oil temperature can be increased. Note that the degree to which the resistance value of the coil reflects the oil temperature may vary from solenoid valve to solenoid valve depending on the arrangement position of the solenoid valve, its use frequency, and the like. Therefore, in order to further improve the detection accuracy, weighting may be performed for each solenoid valve, and the detected value may be multiplied by a coefficient.

Although the above embodiment has been described with reference to an example of a duty-controlled linear solenoid valve, the present invention is not limited to the above embodiment, and other types of solenoid valves may be used. Alternatively, the oil temperature may be detected. Further, in the above embodiment, the example in which the engine water temperature is used as the temperature other than the hydraulic circuit has been described. However, in the present invention, the correction may be performed based on a known external temperature other than the engine water temperature.

[0023]

As described above, according to the oil temperature detecting device of the present invention, the variation in the resistance-temperature characteristics due to the variation among the solenoid valves and the variation due to the installation position of the solenoid valve is reduced by a so-called external circuit other than the hydraulic circuit. Since the correction is performed based on the temperature, the detection of the oil temperature based on the resistance value of the solenoid valve can be made more accurate. In particular, if the above correction is performed in a state where the oil in the hydraulic circuit and the external temperature are estimated to be substantially equal, the correction itself does not include an error or the error is reduced, so that the detection accuracy of the oil temperature is further improved. I do.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the present invention by functional means.

FIG. 2 is a sectional view showing an example of an electromagnetic valve to which the present invention is applied.

FIG. 3 is a circuit diagram schematically showing a circuit for controlling the solenoid valve.

FIG. 4 is a flowchart illustrating a correction routine for a detected resistance value and a control routine for detecting an oil temperature from the corrected resistance value.

FIG. 5 is a resistance-temperature characteristic diagram of a solenoid valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Coil 2 Hydraulic circuit 3 Solenoid valve 4 Temperature detection means 5 Correction means 6 Estimation means

Continuation of the front page (56) References JP-A-60-210807 (JP, A) JP-A-6-174139 (JP, A) JP-A-3-249964 (JP, A) JP-A-4-314964 (JP) JP-A-61-252782 (JP, A) JP-A-61-124787 (JP, A) JP-A-58-108506 (JP, U) 62-18793 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) F16K 31/00-31/11 F16K 37/00 G01K 7/00-7/36

Claims (2)

(57) [Claims] 1. An oil temperature detecting device using an electromagnetic valve for controlling an oil pressure in a hydraulic circuit in accordance with an energized state of a coil and detecting an oil temperature based on a resistance value of the coil. An electromagnetic valve, comprising: temperature detecting means for detecting a temperature other than the hydraulic circuit; and correcting means for correcting a temperature characteristic value with respect to a resistance value of the coil based on a temperature other than the hydraulic circuit. Oil temperature detection device using 2. The apparatus according to claim 1, further comprising estimating means for estimating that the temperature other than the hydraulic circuit is substantially equal to the temperature of the oil in the hydraulic circuit. 2. The solenoid valve according to claim 1, wherein when it is estimated that the temperature is substantially equal, a temperature characteristic value for a resistance value of the coil is corrected based on a temperature other than the hydraulic circuit. Oil temperature detection device using