JPH11351362A - Solenoid control device for automatic transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the warming up performance while electrically heating a solenoid by forbidding the excessive excitation control, and performing the only usual excitation so as to perform the warming up in the condition that a detected oil temperature inside an automatic transmission is lower than the predetermined value. SOLUTION: In case of controlling the excessive excitation at a control cycle (tp) with a controller, usually (a), after starting a plunger of a solenoid valve with the step-like excessive excitation of the excessive excitation A, the thrust of the plunger is maintained by excitation at a constant value of the usual excitation B so as to generate a plunger displacement X. The current I for current carrying the solenoid rises like a step, and thereafter, the current I is maintained at a constant value. In this case, temperature Tc rises large, and the plunger is moved. At the time of a remarkably low temperature (b), the excessive excitation A is forbidden, and the only constant excitation is performed. The plunger is not displaced, but since the constant current carries in the solenoid with the usual excitation, the temperature Tc is raised by the electrical heating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic transmission in which the gear ratio can be changed, and the valve element is controlled only by an over-excitation control in which a step-like over-excitation is generated with respect to a normal excitation of a constant value. The present invention relates to a solenoid control device for an automatic transmission including a solenoid capable of starting a solenoid.

[0002]

2. Description of the Related Art As a technique for promoting warm-up when oil in an automatic transmission is in a very low temperature state, there is a technique disclosed in Japanese Utility Model Laid-Open No. 62-104049, for example. This is because, in a stepped automatic transmission in which gear shifting is performed by switching a plurality of gears, among solenoid valves required for gear shifting, a solenoid of the electromagnetic valve not involved in the gear shifting is energized. Then, the solenoid is caused to generate heat electrically, thereby improving the warm-up performance.

[0003]

However, for example, in a continuously variable automatic transmission such as a V-belt type or a toroidal type in which the gear ratio can be changed steplessly, a plurality of gears are required to switch gears. There is no need to use a solenoid valve, and there is no solenoid valve that can be stopped for operation because it is constantly controlled. For this reason, in the above-described conventional apparatus, warming-up cannot be promoted even when the oil in the continuously variable automatic transmission is in a very low temperature state.

Some electromagnetic valves have a solenoid that can start the valve only by over-excitation control. The overexcitation control starts the valve element by overexciting the solenoid in a stepwise manner, and the thrust of the valve element is maintained by normal excitation in which a constant value is applied to excite the valve element. In this case, the thrust required for starting the valve element is insufficient with only the normal excitation that does not cause overexcitation, so that the position of the valve element is maintained as it is immediately before the excitation. Heretofore, such a solenoid valve has been conventionally used, for example, in a line pressure control circuit system of a stepped or continuously variable automatic transmission.

The problem to be solved by the present invention has been made in view of such a fact. In an automatic transmission in which the number of solenoid valves used for shifting is small, it is possible to start the valve only by overexcitation control. An object of the present invention is to provide a solenoid control device for an automatic transmission that can improve warm-up performance by electrically heating a possible solenoid.

[0006]

In order to solve this problem, a solenoid control device for an automatic transmission according to a first aspect of the present invention is an automatic transmission capable of changing a gear ratio, and has a constant value. In a solenoid control device of an automatic transmission having a solenoid capable of starting a valve only by overexcitation control that generates a step-like overexcitation with respect to normal excitation, oil detected in the automatic transmission In a state where the temperature is lower than a predetermined value, in order to perform warm-up, the overexcitation control is prohibited, and only the normal excitation is performed.

The device according to the second invention is characterized in that, in the first invention, when the vehicle is under a high load, the output time of the normal excitation is shorter than when the vehicle is under a low load. is there.

Further, the device of the third invention is characterized in that, in the first or second invention, the output time of the normal excitation can be changed according to the oil temperature detected in the automatic transmission. It is.

[0009] In addition, the device of the fourth invention comprises the first to third devices.
In any one of the inventions, when the output of the battery power supply falls below a predetermined value, the warm-up by the normal excitation is not performed even in a region where the warm-up is required. .

[0010] In addition, the device of the fifth invention is characterized in that, in any one of the first to fourth inventions, when an abnormality is detected in the solenoid, the solenoid is not excited. Things.

[0011]

According to the first aspect of the present invention, a solenoid control device for an automatic transmission starts a valve body by over-excitation control in which a solenoid is over-excited in a step-like manner, and then takes a constant value for the solenoid. A device that maintains the thrust of the valve body by normal excitation to be excited, and adjusts the pressure by positioning the valve body according to the output time of the normal excitation. When the oil temperature falls below a predetermined value, it is determined that the engine is in an extremely low temperature state requiring warm-up, the overexcitation control for the solenoid is prohibited, and only the normal excitation is performed. Accordingly, the solenoid can be heated electrically at an extremely low temperature requiring warm-up without starting the valve body.

Therefore, according to the device of the first aspect of the present invention, it is possible to promote the warming-up in the cryogenic state while maintaining the pressure state adjusted by positioning the valve body. Performance is improved.

Further, since the oil temperature rise in a high load state is faster than the oil temperature rise in a low load state, the device of the second invention is characterized in that, in the first invention, when the vehicle is in a high load state in which the oil temperature rises rapidly. If there is, the output time of the normal excitation is shortened as compared with the low load state where the oil temperature rise is slow. In this case, the amount of power consumption in a high load state can be reduced, so that fuel efficiency can be improved.

Further, the device according to the third aspect of the present invention includes the first or second device.
In the present invention, since the output time of the normal excitation can be changed according to the oil temperature detected in the automatic transmission, power can be efficiently supplied to the excitation unit in accordance with the oil temperature state, so that fuel consumption is further reduced. improves.

[0015] In addition, the device of the fourth invention comprises the first to third devices.
In any one of the inventions, when the output of the battery power supply falls below a predetermined value, the warm-up by the normal excitation is not performed because the output of the battery power supply is in a low state even in an area where warm-up is required. In this case, the battery power is
Even when the output of the battery power supply is low, the basic functions of the power supply of the engine starting, ignition, lighting and other electric components are not impaired.

In addition, in the device according to the fifth aspect of the present invention, when an abnormality in the solenoid is detected in any one of the first to fourth aspects of the present invention, the solenoid is not excited.
In this case, since the output of the battery power is not supplied to the solenoid, the inconvenience that the solenoid does not function properly, for example, insufficient heating of the solenoid or excessive heat generation is solved. Further, it is possible to prevent the performance of the automatic transmission from deteriorating due to the solenoid abnormality.

[0017]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows a shift control device illustrated together with a line pressure control device of a V-belt type continuously variable transmission. Reference numeral 1 denotes an engine rotation N (not shown).
primary pulley as input pulley to which e is input,
Reference numeral 2 indicates a secondary pulley as an output pulley that outputs the rotation after shifting. The V-belt 3 is wound around the primary pulley 1 and the secondary pulley 2, and the transmission ratio between the pulleys, that is, the gear ratio, can be changed steplessly by changing the arc diameter of the V-belt 3 wound on both pulleys 1 and 2. And

For this reason, the primary pulley 1 allows the movable flange 1b, which forms the pulley V-groove to face the fixed flange 1a, to be displaceable in the axial direction.
Also, the movable flange 2b that forms the pulley V groove facing the fixed flange 2a can be displaced in the axial direction. A shift control pressure Ps is applied to the movable flange 1b in a direction toward the fixed flange 1a, and a line pressure PL is applied to the movable flange 2b in a direction toward the fixed flange 2a. The speed is changed by changing the diameter of the arc around which the V-belt 3 is wound around both pulleys 1 and 2 steplessly in accordance with the differential pressure.

Here, a line pressure control system for controlling the line pressure PL will be described.
If a pressure regulator valve 12 for pressurizing regulating the hydraulic oil from the pressure source 11 to the line pressure PL, a pressure modifier valve 13 for supplying the modifier pressure P _m of the line pressure control to the regulator valve 12,
It comprises a line pressure solenoid valve (electromagnetic valve) 14 for controlling the modifier valve 13 and a pilot valve 15 for supplying a constant pressure Pc to the solenoid valve 14.

The pressure regulator valve 12, while leakage of hydraulic oil from the pressure source 11 to the circuit 16, also with a drain from the drain port 12a as necessary, adjusting the line pressure PL in accordance with the modifier pressure P _m Press. The pilot valve 15 removes oil leaking from the circuit 16 to a constant pressure Pc.
Is supplied to the line pressure solenoid valve 14, which supplies a constant pressure Pc to the drive duty output value Dt.
Modifier valve 13 with duty pressure PD corresponding to
Is applied. Modifier valve 13, the leak oil from the circuit 16, the duty pressure PD, i.e., the modifier pressure P _m corresponding to the duty output value Dt of the line pressure solenoid valve 14, which pressure regulator valve 12
To adjust the line pressure PL. Therefore, the line pressure PL can be controlled by adjusting the duty output value Dt of the line pressure solenoid valve 14, and this duty output value Dt is determined by the controller 17 as described later.

The controller 17 also performs a speed change control. For the speed change control and the line pressure control, the controller 17 sends a signal from a throttle opening sensor 18 for detecting the throttle opening TVO of the engine, a primary pulley, and the like. The signal from the primary pulley rotation sensor 19 for detecting the rotation Npri
Pulley rotation sensor 2 that detects the rotation Nsec of
0, a signal from an engine rotation sensor 27 for detecting the engine rotation Ne, and a selection range of a manual valve (not shown) operated according to a driving mode (R, N, D) desired by the driver. A signal from the inhibitor switch 28 to be detected is input. Note that the secondary pulley rotation sensor 20 of the present embodiment functions as a vehicle speed sensor used to calculate the vehicle speed VSP, so that any one of the shafts from the output side of the secondary pulley 2 to a differential gear device (not shown) is used. An output shaft rotation sensor that can detect rotation may be used.

Next, the transmission control system will be described. The transmission control valve 21 for determining the transmission control pressure Ps and the transmission link 22
And a step motor 23. Transmission link 22
Has one end connected to a shifter 24 displaced together with the primary pulley movable flange 1b, and the other end connected to a step motor 23.
And a shift control valve 21 between both ends.
Pivotally attached to the spool 21a. Here, the shift control valve 21 reduces the line pressure PL from the circuit 25 to produce a shift control pressure Ps in the circuit 26. When the spool 21a is raised in the drawing, the shift control pressure circuit 26 is switched to the line pressure circuit 25. When the spool 21a is lowered in the drawing, the transmission control pressure circuit 26 is connected to the drain port 2 when the spool 21a is lowered in the drawing.
1b, the shift control pressure Ps is reduced, and the stroke of the spool 21a is controlled by the step motor 23 via the shift link 22. Then, the rotational position of the step motor 23 is determined by the controller 17, whereby the following shift control is executed.

In this shift control, the controller 17
Calculates the target input rotation Ni from the vehicle speed VSP and the throttle opening TVO based on, for example, a map corresponding to the shift control characteristics shown in FIG. 2, and issues a shift command corresponding to this to the step motor 23. As a result, the step motor 23 comes to the rotational position as instructed, and the speed change link 2
2 is rotated around the shifter 24 to make the spool 21a of the shift control valve stroke. Thereby, the shift control valve 21
Sets the circuit 26 to the line pressure circuit 25 and the drain port 2
Deviating from the equilibrium position which is made the same for 1b,
By changing the shift control pressure Ps and displacing the movable flanges 1b and 2b of the pulleys 1 and 2, the speed ratio is brought to a speed ratio corresponding to the target input rotation Ni.

As the shift progresses, the movable flange 1b of the primary pulley 1 rotates the shift link 22 via the shifter 24 around the step motor 23 so as to return the spool 21a of the shift control valve to the original stroke position. When the speed change reaches the speed ratio corresponding to the target input rotation Ni, the speed change control valve 21 returns to the equilibrium position to end the speed change control and maintain the target speed ratio.

FIG. 3 is a system diagram illustrating an embodiment of the apparatus of the present invention. The CVT controller 31
The signal from the throttle opening sensor 18, the signal from the secondary pulley rotation sensor (output shaft rotation sensor) 20, the signal from the engine rotation sensor 27, the signals R, N, D from the inhibitor switch 28, and the oil in the automatic transmission A signal from an oil temperature sensor 29 for detecting the temperature T is input, and a battery from a battery power source 30 is used as a power source for the step motor 23 and as a power source for supplying a current I to the solenoid 14s of the line pressure solenoid valve 14. Voltage IGN is input. The CVT controller 3
1 may be the same as the controller 17 of the present embodiment, but may be provided separately from the controller 17 and independently control the solenoid 14s.

In the present embodiment, in order to control overexcitation of the solenoid 14s, as shown in a region S of FIG. 3, an overexcitation circuit is formed by the first circuit A and the second circuit B, and The circuit B includes a dropping resistor R. By changing the currents applied to these two circuits A and B respectively, the overexcitation control of the solenoid 14s is performed.

FIG. 4 shows a part of the CVT controller 31. The CPU (Central Processing Unit) 310 for duty-controlling the current I to be supplied to the solenoid 14s based on the input value, and the CPU 310 A drive circuit 312 for adjusting the current supplied to each of the circuits A and B based on the battery voltage IGN based on the duty outputs Dta and Dtb from the duty output 311 of the circuit A, and a failure of the overexcitation voltage of the circuit A and the battery voltage IGN. An AD conversion unit 313 of the CPU 310 that performs detection. Note that the duty outputs Dta and Dtb are obtained from a duty output value Dt described later.

FIG. 5 is a flowchart for changing the duty output value Dt by detecting the failure of the solenoid 14s and the battery power supply 30 and the presence or absence of warm-up. This control is performed every predetermined time, and the predetermined time is, for example, every 5 (msec).

First, at step 50, the engine speed Ne
, The vehicle speed VSP, the throttle opening TVO, the inhibitor signals R, N, D, the battery voltage IGN, and the oil temperature T are read as input signals, and the routine goes to step 51. In this step 51, the failure of the solenoid 14s shown in FIG. Make a decision. This is, as shown in FIG.
The actual solenoid voltage value is compared with the theoretical solenoid voltage value obtained by the duty output value Dt calculated by the following equation, and when the two values do not match, the solenoid 14s
Is determined to be abnormal. If it is determined in step 52 that the solenoid is not a solenoid failure, the process proceeds to step 53 assuming that the solenoid 14s is functioning normally.

However, if it is determined in step 52 that the solenoid has failed, it is determined that the solenoid 14s is abnormal, and the routine proceeds to step 59, where the warm-up flag F is set to "F =
By clearing to "0" and stopping the duty output in step 60, the function of the line pressure solenoid valve 14 is stopped.

Therefore, when a failure of the solenoid 14s is detected, the solenoid 14s is not excited. In this case, since the output of the battery power supply 30 is not supplied to the solenoid 14s, the inconvenience that the solenoid 14s does not function properly, for example, insufficient heating of the solenoid 14s or excessive heat generation of the solenoid 14s is solved. .

When the solenoid 14s functions normally, in step 53, the battery power supply 3 is used to detect whether or not the output of the battery power supply 30 is low.
It is determined whether the voltage IGN of 0 is equal to or higher than a predetermined value IGN (o). If the battery voltage IGN is equal to or higher than the predetermined value IGN (o), it is determined that the battery power source 30 is functioning normally.
Move to step 54.

However, when the battery voltage IGN is a predetermined value IGN
If it is less than (o), it is determined that the output of the battery power supply 30 is in a low state, and the routine proceeds to step 61, where the warm-up flag F is cleared to “F = 0”. That is, only the duty output value necessary for performing the shift control is calculated. In this case, even if the output of the battery power supply 30 is in a low state, the basic functions as the power supply for starting the engine, ignition, lighting, and other electric components are not impaired.

If the battery power supply 30 is functioning normally, at step 54, the transmission oil temperature T is set to a predetermined value T ( o) is determined as follows. Transmission oil temperature T
Is less than or equal to the predetermined value T (o), it is determined that the oil in the transmission is in a very low temperature state that requires warm-up, and the routine proceeds to step 55, where the warm-up flag F is incremented to "F = 1". However, if the transmission oil temperature T exceeds a predetermined value T (o), it is determined that the oil temperature state does not require warm-up, and Step 61,
The program of 62 is executed.

If the oil in the transmission is in a very low temperature state that requires warm-up, in steps 56 and 57, a basic duty value Dt (o) for obtaining a duty output value Dt and a correction amount ΔDt are calculated.

First, at step 56, the basic duty value Dt (o) is calculated.
The calculation is preferably performed in accordance with the oil temperature T. For example, the calculation is performed in accordance with the oil temperature T and the basic duty value Dt shown in FIG.
The change characteristic diagram with (o) is used. Specifically, when the oil temperature T1 is detected by the oil temperature sensor 30, the basic duty value is Dt (o) = D1 (%).

In step 57, a correction amount ΔDt is calculated.
N, D, the throttle opening TVO, and the vehicle speed VSP are preferably calculated.
Utilize the map diagram shown in. Specifically, for example, in the D range, the throttle opening is TVO = 6/8 and the vehicle speed is V
When traveling at SP = 60 (km / h), in the map of FIG.
The shift range position is (D, Ds), the throttle opening TVO
Is (.about.8 / 8) and the vehicle speed VSP is (30.about.100). Therefore, the required correction amount is .DELTA.Dt = 0.7. In the case of the N range, or when the vehicle is running in the R range and the throttle opening TVO is (〜2 / 8), the required correction amount is uniform regardless of the vehicle speed VSP, and ΔD = 1.0
And

In step 58, the basic duty value Dt (o) and the correction amount ΔDt obtained in steps 56 and 57 are substituted into Dt = Dt (o) × ΔDt (1), and the duty output value Dt ( %). The duty outputs Dta and Dtb from the drive circuit 311 are determined by the duty output value Dt.

FIG. 6 is a flowchart for determining the time for exciting the solenoid 14s. The line pressure solenoid valve 14 controls the displacement of a plunger (valve element) 14a in the line pressure solenoid valve by exciting the solenoid 14s to ON.

Therefore, in step 70, it is determined whether ON should be output to the solenoid 14s this time. If it is determined that ON should be output to the solenoid 14s, it is determined that it is necessary to perform warm-up or to operate the line pressure solenoid valve 14, and Step 71 is performed.
Then, at step 71, the failure detection of the solenoid 14s is performed. However, if it is determined that ON should not be output to the solenoid 14s this time, step 7
Then, the time when the solenoid 14s was turned OFF last time is calculated backward, and the process proceeds to step 74 described later.

If the failure of the solenoid 14s is not detected in step 71, it is determined that the solenoid 14s is functioning normally, and the routine proceeds to step 72, where it is determined whether or not the transmission oil temperature T is in a cryogenic state requiring warm-up. judge. However, if a failure of the solenoid 14s is detected in step 71, the process proceeds to step 76, where the time ta during which overexcitation is output to the circuit A is cleared to ta = 0 (2). The time tb during which the normal excitation is output to the circuit B is cleared to tb = 0 (3).

Therefore, when a failure of the solenoid 14s is detected, the solenoid 14s is not excited. In this case, since the output of the battery power supply 30 is not supplied to the solenoid 14s, the inconvenience that the solenoid 14s does not function properly, for example, insufficient heating of the solenoid 14s or excessive heat generation of the solenoid 14s is solved. .

In step 72, if the warm-up flag F is "F = 1", it is determined that the transmission oil temperature T is in a very low temperature state requiring warm-up, and the routine proceeds to step 73. However,
If the warm-up flag F is not "F = 1", it is determined that the transmission oil temperature T is not in the extremely low temperature state requiring warm-up, and the routine proceeds to step 77, where the solenoid 14s is overexcited and the plunger 14
After starting a, the plunger 14 is excited to a constant value.
a, the line pressure solenoid valve 1
In order to adjust the pressure output from the circuit 4, the time ta during which the over-excitation is output to the circuit A is defined as: ta = min (predetermined value, Dt × tp) (4) tp), and
The smaller value is set as the time ta, and the time tb during which the normal excitation is output to the circuit B is set as tb = Dt × tp (5). Reference numeral tp denotes a control cycle for detecting the excitation state of the solenoid 14s (see FIG. 10), whereby the excitation state of the solenoid 14s is detected at every constant control cycle tp.

In step 72, if the transmission oil temperature T is in a very low temperature state requiring warm-up, the process proceeds to step 73, in which overexcitation control is prohibited and only normal excitation is performed. The output time ta is cleared to ta = 0 (6), and the time tb during which the normal excitation is output to the circuit B is set to tb = Dt × tp (7).

In this case, as shown in the above equation (7), the time tb during which the normal excitation is output is the duty output value Dt obtained from the equation (1), that is, the basic duty value Dt.
t (o) (see FIG. 8) and the correction amount ΔDt (see FIG. 9).

Since the oil temperature rise in a high load state is earlier than the oil temperature rise in a low load state, if the vehicle is in a high load state in which the oil temperature rises quickly, the oil temperature rises in a low load state in which the oil temperature rises slowly. In comparison, it is preferable to shorten the time tb during which the normal excitation is output to the circuit B.

Therefore, in this embodiment, the correction amount ΔDt
9, as shown in FIG. 9, the state in which the throttle opening TVO is high is set smaller than the state in which the throttle opening TVO is low. For this reason, when calculating the duty output value Dt from Equation (1), if the value of the basic duty value Dt (o) is fixed and considered, the duty output value Dt will be higher in the high load state than in the low load state of the vehicle. Is smaller.

Therefore, as is apparent from the equation (7), the time tb during which the normal excitation is output to the circuit B is higher in the high load state where the oil temperature rises faster than in the low load state where the oil temperature rises slowly. Is shorter. In this case, the amount of power consumption in a high load state can be reduced, so that fuel efficiency can be improved.

Similarly, the basic duty value Dt (o) is calculated as shown in FIG.
As shown in FIG. 5, since it changes in accordance with the oil temperature T and decreases as the oil temperature increases, when calculating the duty output value Dt from the equation (1), if the value of the correction amount ΔDt is considered fixed, The duty output value Dt also decreases as the oil temperature T detected in the transmission increases.

Therefore, the time tb during which the normal excitation is output to the circuit B decreases with the oil temperature T, as is apparent from the equation (7), and the output time tb of the normal excitation depends on the oil temperature T.
Can be changed, power can be efficiently supplied to the excitation unit (region S in FIG. 3) in accordance with the state of the oil temperature T.
Further, fuel efficiency is improved.

In step 74, the duty output value Dt
The next interruption time is newly set by the time tb at which the normal excitation is output.

FIG. 10 is a time chart showing the operation of the apparatus of the present invention. 3A, 3B, and 3C respectively show overexcitation A, normal excitation B, plunger displacement X, current I, and solenoid temperature when the CVT controller 31 performs overexcitation control at the control cycle tp. FIG. 3A shows the case where the plunger 14a of the solenoid valve 14 is displaced by the overexcitation control at the time of normal (high temperature), and FIG. FIG. 3C shows a case where the warm-up is performed by the solenoid control by the conventional device when the warm-up is performed by the solenoid control.

FIG. 10 (a) shows a plunger 14a of the solenoid valve 14 due to the step-like overexcitation indicated by overexcitation A.
Is started, the thrust of the plunger 14a is maintained by the excitation having a constant value indicated by the normal excitation B, and the plunger 14a is displaced as indicated by the plunger displacement X. The output pressure from the solenoid valve 14 is adjusted by positioning the plunger 14a in accordance with the output time tb of the normal excitation B. In this case, the current I for energizing the solenoid 14s takes a constant current value after rising in a stepwise manner for overexcitation. However, in this case, the solenoid 1
Although the temperature Tc at 4s rises significantly, the plunger 14a also moves.

However, FIG. 10 (b) showing the warming-up action of the present invention at a very low temperature is shown in FIG. 10 (b). As shown by X, the plunger 14a of the solenoid 14 does not displace, but a constant current flows through the solenoid 14s due to normal excitation, and the temperature Tc of the solenoid 14s rises due to electrical heating.

On the other hand, at the time of extremely low temperature, in the conventional FIG. 10 (c), since the over-excitation control A and the normal excitation B cannot be individually controlled, a constant current or an over-current is supplied to the solenoid 14s so that the plunger , The solenoid 14s cannot be electrically heated.

According to the present invention, the plunger 14 is controlled by overexcitation control A in which the solenoid 14s is overexcited stepwise.
After starting the solenoid a, the thrust of the plunger 14a is maintained by the normal excitation B for exciting the solenoid 14s at a constant value, and the plunger 14a is positioned in accordance with the output time tb of the normal excitation B to reduce the pressure. An over-excitation control A for the solenoid 14s, which determines that the oil temperature T detected in the continuously variable automatic transmission falls below a predetermined value and that the engine is in a very low temperature state requiring warm-up.
And only the normal excitation B is performed. Accordingly, the solenoid 14s can be electrically heated without starting the plunger 14a at the time of extremely low temperature requiring warm-up.

Therefore, according to the apparatus of the present invention, it is possible to promote the warming-up in the extremely low temperature state while maintaining the pressure state adjusted by positioning the plunger 14a, thereby improving the warming-up performance. I do.

The foregoing merely illustrates preferred embodiments of the present invention, and those skilled in the art will be able to make various modifications within the scope of the appended claims. For example, the automatic transmission is not limited to a V-belt or toroidal continuously variable transmission, but may be a stepped automatic transmission. Further, in the present embodiment, the line pressure solenoid valve 14 has been described as an electromagnetic valve, but a two-way valve or a three-way valve may be used as long as the valve body is started by over-excitation control. Further, the valve body is not limited to the plunger, and may be a spool or a ball-shaped structure.

[Brief description of the drawings]

FIG. 1 shows a line pressure control device of a V-belt type continuously variable transmission.
FIG. 3 is a hydraulic control system diagram exemplified together with a shift control device.

FIG. 2 is a diagram showing a normal shift control pattern used for shift control in the example.

FIG. 3 is a system diagram showing one embodiment of the present invention.

FIG. 4 is a system diagram illustrating a solenoid drive circuit according to the embodiment;

FIG. 5 is a flowchart for calculating a duty output value to a solenoid according to an embodiment of the present invention.

FIG. 6 is a flowchart for calculating an overexcitation output time and a normal excitation time in the same embodiment.

FIG. 7 is a flowchart for performing a failure determination of a solenoid.

FIG. 8 is a change characteristic diagram for calculating a basic duty value with respect to an oil temperature.

FIG. 9 is a map diagram for calculating a correction amount for a basic duty output value from a shift range, a throttle opening, and a vehicle speed.

10 (a) and 10 (b) are time charts for explaining the device of the present invention, and FIG. 10 (c) is a time chart for explaining the conventional device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Primary pulley 2 Secondary pulley 3 V belt 11 Pressure source 12 Pressure regulator valve 13 Pressure modifier valve 14 Line pressure solenoid valve 14a Plunger 14s Line pressure solenoid 15 Pilot valve 16 Circuit 17 Controller 21 Transmission control valve 21a Spool 22 Transmission link 23 Step Motor 24 Shifter 25 Line pressure circuit 26 Shift control pressure circuit 31 CVT controller

Claims (5)

[Claims] An automatic transmission capable of changing a gear ratio, wherein a valve element can be started only by an overexcitation control that generates a step-like overexcitation with respect to a normal excitation that is excited at a constant value. In a solenoid control device for an automatic transmission having a simple solenoid, in a state where the oil temperature detected in the automatic transmission is lower than a predetermined value, in order to warm up, the overexcitation control is prohibited and only the normal excitation is performed. A solenoid control device for an automatic transmission. 2. The solenoid control device for an automatic transmission according to claim 1, wherein when the vehicle is under a high load, the output time of the normal excitation is shorter than when the vehicle is under a low load. 3. The solenoid control device for an automatic transmission according to claim 1, wherein the output time of the normal excitation can be changed according to the oil temperature detected in the automatic transmission. 4. The apparatus according to claim 1, wherein when the output of the battery power supply falls below a predetermined value, the warm-up by the normal excitation is not performed even in a region where warm-up is required. A solenoid control device for an automatic transmission according to any one of the preceding claims. 5. The solenoid control device for an automatic transmission according to claim 1, wherein when an abnormality is detected in the solenoid, the solenoid is not excited.