JP3205444B2 - Solenoid drive control device for automatic transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for driving a solenoid in a hydraulic control device of an automatic transmission with good responsiveness and always with predetermined rising characteristics.

[0002]

2. Description of the Related Art Solenoids used in automatic transmissions, especially linear solenoids, are required to have the ability to quickly follow a target value when the target value changes in order to perform feedback control well. However, in general, there is a problem that the linear solenoid itself is expensive, and if it has a quick response, it becomes more expensive.

[0003] Therefore, conventionally, when driving a linear solenoid of an automatic transmission, a large current is applied temporarily (for a fixed time immediately after the start of driving) and then reduced to a target current value. A control device has been proposed in which the linear solenoid is configured so that the rise (response) of the linear solenoid can be accelerated even if it is not a linear solenoid, and the target hydraulic value can be quickly reached.

In view of the fact that the response of the linear solenoid deteriorates as the oil temperature decreases, the value of the large current and the time for supplying the large current are determined depending on the oil temperature of the automatic transmission. In addition, there has been proposed a technique intended to secure a predetermined rising characteristic irrespective of an oil temperature in an automatic transmission (Japanese Patent Application Laid-Open No. 2-142966).

[0005]

However, even if the oil temperature of the automatic transmission is detected and the start-up characteristic of the solenoid is determined based on the detected oil temperature, the above-mentioned movement of the solenoid is actually changed by the automatic transmission. In some cases, this does not always correspond to the oil temperature of the machine, and the fact is that sufficient responsiveness improvement cannot be achieved in order to avoid overshoot.

The present invention has been made in view of such a conventional problem, and takes into consideration the oil temperature in the solenoid in addition to the oil temperature of the automatic transmission, and uses a relatively inexpensive solenoid. To provide a solenoid drive control device for an automatic transmission that can obtain stable start-up characteristics with better responsiveness and no overshoot, and to maintain good shift characteristics of the automatic transmission. That is the purpose.

[0007]

According to the present invention, as shown in FIG. 1, when the solenoid is driven by an electric command to control the hydraulic pressure, the rising characteristic of the solenoid is controlled. A means for detecting the oil temperature of the automatic transmission (the entire operating oil temperature), a means for detecting the oil temperature in the solenoid, and an actual temperature from a predetermined map. Means for controlling the rising characteristics of the solenoid based on both the oil temperature of the automatic transmission and the oil temperature in the solenoid are provided, thereby solving the above problem.

In the above configuration, the term "detecting" the oil temperature of the automatic transmission or the oil temperature in the solenoid does not necessarily mean only directly detecting the oil temperature. In the case where there is a parameter that can estimate (indirectly detect) the oil temperature to such an extent that there is no problem in carrying out the present invention, the detection of the oil temperature may be replaced with “detection” of the oil temperature.

[0009]

In general, as the oil temperature of the automatic transmission decreases, the responsiveness of the solenoid deteriorates, but the degree of the deterioration does not always correspond completely to the oil temperature.
That is, for example, when the shift is executed correspondingly by, for example, moving the accelerator after starting, the oil temperature inside the solenoid tends to be relatively high (even though the oil temperature of the entire automatic transmission is low), As a result, the solenoid itself can rise relatively smoothly. However, if the vehicle enters the constant speed state immediately after starting, the oil temperature inside the solenoid is still low, and as the engine warm-up is promoted, an automatic The oil temperature inside the solenoid rises only to the extent that it rises as the oil temperature in the transmission rises. Therefore, even if a drive signal is given to the solenoid in this state, it cannot be started up well.

That is, generally, when the solenoid is driven, the oil between the plunger and the case or the core or the oil between the plunger and the cover is moved with the movement of the plunger inside the solenoid. At low temperatures, the fluidity of the oil deteriorates and the resistance increases. This is the biggest cause of the deterioration of the response. In addition, the oil viscosity is high at low temperatures, and the sliding resistance of the spool increases because the valve clearance between the spool and the sleeve becomes smaller than that at normal temperature. One.

The occurrence of these causes is greatly related to the oil temperature inside the solenoid rather than the oil temperature of the automatic transmission (the entire operating oil temperature).

The oil temperature inside the solenoid is, of course, greatly affected by the entire oil temperature of the automatic transmission, but may not always correspond as described above.

In general, it is obvious that the responsiveness can be further improved by increasing the initial current and increasing the time during which the initial current is supplied. Become. Conventionally, the oil temperature inside the solenoid may already be high even though the overall oil temperature is low. The fact was that they couldn't be enlarged. For this reason, it has not been possible to obtain sufficient responsiveness improvement.

Therefore, in the present invention, not only the (overall) oil temperature of the automatic transmission but also the oil temperature in the solenoid is detected, and the rising characteristics of the solenoid are controlled based on both of them. Things.

As a result, the rising characteristics of the actual solenoid can be accurately controlled in accordance with the "movability" of the actual solenoid, so that the responsiveness can be improved to the utmost and the operating environment can be improved. Regardless, it is possible to always obtain a stable (without overshoot) rising characteristics.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 2 shows a linear solenoid in an automatic transmission to which the present invention is applied.

In the drawing, reference numeral 2 denotes a linear solenoid, 4
Is a coil, 6 is a case, 8 is a cover, 10 is a pin, 12
Is a plunger, 14 is a core, 16 is a spool, 18 is a sleeve, and 20 is a spring.

The linear solenoid 2 is known per se, and the plunger 12 slides in the axial direction (the direction of the arrow X) according to the current flowing through the coil 4, and is connected to the plunger 12 by this sliding. The pin 10 slides in the axial direction X, and the spool 16 pressed against the pin 10 by the spring 20 is moved and positioned in the axial direction. As a result, the drain amount from the port 24 is increased / decreased with respect to the line pressure input from the port 22, and a hydraulic pressure corresponding to the current passed through the coil 4 is output from the port 26.

Here, when the plunger 12 moves in the axial direction in accordance with the current passed through the coil 4, the oil moves between the space A in FIG. At low temperatures, this movement is not performed smoothly due to an increase in the viscosity of the oil, resulting in poor responsiveness.

The spool 16 is generally formed of an iron-based material, while the sleeve 18 is formed of an aluminum-based material having a larger thermal expansion coefficient. Therefore, the sleeve 18 reacts more sensitively to heat, and at a low temperature, the inner diameter of the sleeve 18 becomes smaller at a larger ratio than the outer diameter of the spool 16 becomes smaller. This is one of the factors that deteriorate the characteristics.

Therefore, the present invention is applied to the linear solenoid 2 having such a configuration so that a predetermined rising characteristic can be obtained regardless of the temperature environment.

FIG. 3 shows the coil 4 of the linear solenoid 2.
Shows a circuit for supplying a current to the circuit.

From the CPU 30 of the automatic transmission, the coil 4
Is output. The duty signal is, as shown in FIG. 4, a rectangular wave of 300 Hz, and changes the on-time and off-time within one hertz as shown in, for example, (A) to (C). Thus, increase / decrease control of the current (average current) supplied to the coil 4 is performed.

The reference numeral 32 in FIG. 3 denotes a transistor.
The switching function of applying the battery voltage to the solenoid 4 is performed only when the duty signal is turned on.

In this embodiment, the oil temperature in the solenoid is estimated from the resistance Rsol of the coil 4. Therefore, the coil 4
A resistor 34 is arranged on the ground side of the resistor 34, and the voltage (battery voltage) Vb on the hot side of the transistor 32 and the average voltage Vi on the hot side of the resistor 34 are detected. The battery voltage Vb and the average voltage Vi applied to the resistor 34 are converted to an analog-digital converter 36.
Is input to the CPU 30 via the.

Next, the operation of this embodiment will be described with reference to FIG.

First, in step 102, the coil 4
Is determined based on the equation (1).

Rsol = Ri × {(Vb−Vi) / Vi} (1)

In the equation (1), Ri is the resistance value of the resistor 34. In the equation (1), since the coil 4 and the resistor 34 are arranged in series, the currents I flowing through both become equal, so that I = Vi / Ri = (Vb-Vi) / Rsol
Is established.

In step 104, the temperature θc of the coil 4
Is obtained from a map as shown in FIG. 6 based on the resistance Rsol of the coil 4.

Next, a dependence coefficient A of the oil temperature θsf inside the solenoid with respect to the oil temperature θf of the automatic transmission is obtained from a map based on the equation (2).

A = MAP [{(Vb−Vi) ² / Rsol−k (θc−θf)} dt] (2)

(Vb−Vi) ² / Rsol of the equation (2)
Is the power consumption W = (Vb−Vi) / R in the coil 4.
It is equivalent to sol × (Vb−Vi), and indicates the amount of heat generated by the coil 4.

On the other hand, k (θc-θf) indicates how much the generated heat escapes from the solenoid. The difference between the temperature θc of the coil 4 and the surrounding oil temperature (total oil temperature) θf is represented by k (θc−θf). Because it depends, it is obtained by multiplying this by a positive constant k. Then, a map showing the extent to which the oil temperature θsf inside the solenoid depends on the entire oil temperature θf of the automatic transmission by using a map from an integrated value obtained by subtracting the divergence amount from the power consumption (heat generation amount) of the coil 4. (Dependency coefficient) A is obtained.

As is clear from the equation (2), the larger the value in [], the closer the oil temperature θsf inside the solenoid is to the temperature θc of the coil 4, and the value of A approaches 0. I have. On the other hand, when the value in [] is small, the oil temperature θsf inside the solenoid is closer to the entire oil temperature θf, and A approaches the value of 1. As is clear from the above description, A is a coefficient of 0 ≦ A ≦ 1.

When the dependency coefficient A is obtained in this way, the coil temperature θc and the total oil temperature θf are multiplied by the dependency coefficient A or (1−A) in step 108, and the sum thereof is used to calculate the oil temperature θsf inside the solenoid. Is required. The obtained oil temperature θsf inside the solenoid is shown in FIG.
Are reflected in the determination of the rise characteristics.

That is, in step 202, the initial current I1 flowing through the coil 4 in the initial stage of driving is first determined from the oil temperature θsf inside the solenoid and the entire oil temperature θf of the automatic transmission according to a map shown in FIG. Is required. Next, at step 204, from the oil temperature θsf inside the solenoid and the entire oil temperature θf of the automatic transmission, a time T1 during which the initial current is flowing is obtained based on a map as shown in FIG. In FIG. 8 or FIG. 9, the value of the portion where θf is higher than θsf is blank because the oil temperature θf of the automatic transmission is generally higher than the oil temperature θsf inside the solenoid. It is impossible.

In step 206, the rising of the solenoid is controlled by flowing the obtained initial current I1 for the time T1.

As a result of executing the above control flow, FIG.
As shown in FIG. 3, the initial current I0 or the time T0 for flowing the initial current is determined (small for fear of overshoot) in accordance with the oil temperature as in the prior art. Since these values I1 and T1 are determined also depending on the oil temperature, the response, which has been improved only as shown by the two-dot chain line in the conventional figure, can be improved as shown by the solid line without causing overshoot. Be able to lift.

In this embodiment, since it is actually difficult to detect the oil temperature inside the solenoid, the oil temperature inside the solenoid is estimated (indirectly detected) from the resistance or current flowing through the coil 4. However, the present invention does not limit how to actually detect or estimate the oil temperature inside the solenoid.

Similarly, instead of directly measuring the oil temperature of the automatic transmission, the oil temperature may be estimated (indirectly detected) from, for example, the cooling water temperature of the engine having a strong correlation.

[0043]

As described above, according to the present invention, the rising characteristics of the solenoid are controlled in consideration of not only the oil temperature of the automatic transmission but also the actual oil temperature inside the solenoid. (Even if the solenoid is not so expensive), it is possible to obtain an excellent effect that it is possible to obtain a stable rising characteristic with good response and no overshoot regardless of the use environment.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the gist of the present invention.

FIG. 2 is a sectional view of a linear solenoid to which the present invention is applied.

FIG. 3 is a circuit diagram for supplying a current to a coil of the linear solenoid.

FIG. 4 is a diagram showing an example of a duty signal output from a CPU.

FIG. 5 is a flowchart showing a control flow executed in the embodiment.

FIG. 6 is a diagram showing the relationship between the resistance of the coil and the temperature of the coil.

FIG. 7 is a flowchart showing a control flow used to control the start-up characteristic depending on the oil temperature inside the solenoid and the oil temperature of the automatic transmission.

FIG. 8 is a diagram showing a map for determining an initial current flowing through the coil 4 depending on the oil temperature inside the solenoid and the oil temperature of the automatic transmission.

FIG. 9 is a diagram showing a map for determining a time for flowing an initial current depending on an oil temperature inside a solenoid and an oil temperature of an automatic transmission.

FIG. 10 is a diagram showing current characteristics and hydraulic characteristics for explaining the effect of the embodiment.

[Explanation of symbols]

 2: Linear solenoid 4: Coil Rsol: Resistance of coil 4 θc: Temperature of coil 4 θsf: Oil temperature inside solenoid θf: (Overall) oil temperature of automatic transmission A: Dependency coefficient

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-142966 (JP, A) JP-A-4-107370 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16H 61/00-61/24

Claims (1)

(57) [Claims] When a hydraulic pressure is controlled by driving a solenoid according to an electric command, a solenoid drive control device for an automatic transmission which controls a rising characteristic of the solenoid is provided. Means for detecting; means for detecting the oil temperature in the solenoid; and control of the rise characteristics of the solenoid based on both the actual oil temperature of the automatic transmission and the oil temperature in the solenoid from a predetermined map. And a solenoid driving control device for an automatic transmission.