JP3395447B2 - Oil temperature estimation 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 device for estimating the oil temperature of an automatic transmission.

[0002]

2. Description of the Related Art Some vehicles equipped with an automatic transmission detect the oil temperature of the automatic transmission and use the detected oil temperature as a control factor for the automatic transmission and the vehicle.

A method for estimating the oil temperature of an automatic transmission having a torque converter is disclosed in, for example, Japanese Patent Laid-Open No. 5-2726.
In Japanese Patent Laid-Open No. 22-52, attention is paid to the relationship between the capacity coefficient of the torque converter and the oil temperature of the automatic transmission, and the capacity coefficient of the torque converter and the torque coefficient capacity coefficient and the oil temperature of the automatic transmission stored in advance are It has been proposed to estimate the oil temperature of the automatic transmission from the map.

[0004]

However, the estimation of the oil temperature of the automatic transmission by the above-mentioned conventional method can be said to give the oil temperature rise due to heat storage inside the automatic transmission in a unique map, and there are various There was a problem that the oil temperature estimation accuracy of the automatic transmission under the environment was still low.

The present invention has been made to solve the above-mentioned conventional problems, and it is possible to estimate the oil temperature of an automatic transmission with higher accuracy in various environments. The purpose is to provide a device.

[0006]

SUMMARY OF THE INVENTION The invention of claim 1 is a device for estimating the oil temperature of an automatic transmission, as shown in FIG. 1, which is automatic from the engine output and the efficiency of the automatic transmission. From the heat generation amount calculating means for obtaining the heat generation amount of the transmission, the first heat radiation amount calculating means for obtaining the heat radiation amount in the oil cooler from the oil cooler flow rate, and the estimated oil temperature of the automatic transmission and ambient temperature of the automatic transmission. Second heat radiation amount calculation means for obtaining the heat radiation amount from the surface of the automatic transmission to the periphery of the automatic transmission, and the heat radiation amount of the automatic transmission, the heat radiation amount in the oil cooler and the heat radiation amount to the periphery of the automatic transmission are subtracted. And the oil temperature estimating means for newly estimating the oil temperature of the automatic transmission based on the estimated value and the estimated oil temperature of the automatic transmission.

Further, as the gist of the invention of claim 2 is as shown in FIG. 2, the second heat radiation amount calculation means and the oil temperature estimation means are arranged such that the estimated oil of the automatic transmission after the engine is started. By giving the atmospheric temperature as the initial value of the temperature,
Similarly, the above-mentioned object is achieved.

Further, the gist of the invention of claim 3 is shown in FIG.
As shown in FIG. 5, during engine stop, the oil temperature of the automatic transmission during engine stop is estimated from the estimated oil temperature of the automatic transmission and ambient temperature of the automatic transmission, and the second heat radiation amount calculation means and the The oil temperature estimating means, after the engine is started, receives the estimated oil temperature of the automatic transmission while the engine is stopped as an initial value of the estimated oil temperature of the automatic transmission. It has been achieved.

[0009]

According to the present invention, the heat generation amount of the automatic transmission is obtained from the engine output and the efficiency of the automatic transmission, and the heat radiation amount in the oil cooler is obtained from the oil cooler flow rate. From the estimated oil temperature of the automatic transmission and the ambient temperature of the automatic transmission, the heat radiation amount from the surface of the automatic transmission to the surroundings of the automatic transmission is determined.

Then, based on the value obtained by subtracting the heat radiation amount in the oil cooler and the heat radiation amount to the surroundings of the automatic transmission from the heat generation amount of the automatic transmission and the estimated oil temperature of the automatic transmission,
The oil temperature of the automatic transmission is newly estimated.

As described above, the oil temperature of the automatic transmission is estimated based on the balance of the heat quantity, so that the oil temperature estimation accuracy of the automatic transmission under various environments can be improved.

When the atmospheric temperature is used as the initial value of the oil temperature of the automatic transmission after the engine is started,
The (initial) oil temperature of the automatic transmission can be easily estimated without the need for complicated processing.

Further, when the oil temperature of the automatic transmission is continuously estimated even when the engine is stopped and is used as the initial value of the oil temperature of the automatic transmission after the engine is started, the restart is performed immediately after the engine is stopped. Even in such a case, the (initial) oil temperature of the automatic transmission can be accurately estimated.

[0014]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 4 is an overall schematic view of an engine with an automatic transmission to which the present invention is applied. This engine is an intake air amount sensing type electronic fuel injection engine for automobiles, and an automatic transmission (A / T) 100 is connected to its output shaft.

The air sucked from the air cleaner 10 is
The air flow meter 12, the intake throttle valve 14, the surge tank 16, and the intake manifold 18 are sequentially sent. This air is mixed with fuel injected from the injector 22 in the vicinity of the intake port 20 and is further sent to the combustion chamber 26A of the engine body 26 via the intake valve 24. Combustion chamber 26
The exhaust gas generated as a result of the combustion of the air-fuel mixture in A is the exhaust valve 28, the exhaust port 30, and the exhaust manifold 3.
2 and the exhaust pipe (not shown) to the atmosphere.

The air flow meter 12 has an outside air temperature θ.
An intake air temperature sensor 102 for detecting amb is provided. The intake throttle valve 14 rotates in conjunction with an accelerator pedal (not shown) provided in the driver's seat. The intake throttle valve 14 is provided with a throttle sensor 104 for detecting the accelerator opening Θ.

A water temperature sensor 106 for detecting the engine cooling water temperature θ _W is provided in the cylinder block 26B of the engine body 26. Further, a distributor 38 having a shaft rotated by the crank shaft of the engine body 26 is provided with a crank angle sensor 108 for detecting a crank angle from the rotation of the shaft, from which the engine rotation speed Ne is detected. It has become so.

Further, the automatic transmission 100 has a vehicle speed sensor 1 for detecting the vehicle speed v from the rotational speed No of its output shaft.
10. A shift position sensor 112 for detecting the shift position is provided.

Each of these sensors 102, 104, 10
The outputs of 6, 108, 110 and 112 are input to the engine computer 40 or the A / T computer 50.

The engine computer 40 calculates the fuel injection amount and the optimum ignition timing by using the input signals from the respective sensors as parameters, and controls the injector 22 so that the fuel is injected for a predetermined time corresponding to the fuel injection amount. At the same time, the ignition coil 44 is controlled so that the optimum ignition timing is obtained.

An idle rotation speed control valve 42 driven by a step motor is provided in a bypass passage that connects the upstream side of the intake throttle valve 14 and the surge tank 16.

The A / T computer 50 has a function of calculating the oil temperature of the automatic transmission 100 based on the signals of the above-mentioned sensors. Also, the engine computer 4
0 receives the oil temperature information of the automatic transmission 100 from the A / T computer 50 and controls the idle speed control valve 42 so that the idle speed of the engine also considers the oil temperature of the automatic transmission 100. Control. In addition, the A / T computer 50 controls the hydraulic control circuit 60 to perform shift control in consideration of the oil temperature of the automatic transmission 100.

Next, the operation of this embodiment for estimating the oil temperature of the automatic transmission 100 will be described with reference to the control flow charts shown in FIGS.

Q of the heat generation amount of the automatic transmission 100
_{A / T} [W], equivalent heat transfer coefficient is A [W / ℃], equivalent heat capacity coefficient is C [J / ℃], oil temperature is θ _{A / T} [℃], ambient temperature is θ air [℃], In addition, the heat radiation amount of the oil cooler is Q
_{When O / C} [W], the following equation (1) is established.

Q _{A / T} = Q _{O / C} + A · (θ _{A / T} −θ air) + C · d θ _{A / T} / dt (1)

In this embodiment, the oil temperature of the automatic transmission 100 is estimated based on the equation (1) based on the information from the sensors and the map value given in advance.

The estimation procedure will be described below with reference to a flowchart.

The flowchart of FIG. 5 shows a first control example.

When this flow starts, first in step 200, the engine is started, and in step 20
In 2, the initial values of the automatic transmission oil temperature θ _{A / Ti} and the automatic transmission equivalent heat capacity coefficient Ci are set. Where index i
Represents the number of main processes for estimating the oil temperature, and as will be shown later, a new value θ _{A / Ti + 1} is estimated using the current value θ _{A / Ti} . Here, the initial value (θ _{A / T0} ) of the automatic transmission oil temperature θ _{A / Ti} is the outside air temperature θ detected by the intake air temperature sensor 102.
amb, and the initial value (C
₀ ) is the heat capacity Coil of the oil. That is, the following (2)
The initial value is defined by an expression.

Θ _{A / T0} = θ amb C ₀ = Coil (2)

The outside air temperature θamb may be input from the outside air temperature sensor of the automatic air conditioner.

Next, at step 204, the torque converter efficiency η _{T / C} is determined. This is the ratio (speed ratio) Nt / Ne of the turbine speed Nt and the engine speed Ne.
And the torque converter efficiency η _{T / C} are given in advance by a map as shown in FIG. 6, and by this map,
It is determined by the following equation (3).

Η _{T / C} = f ₁ (Nt / Ne) (3)

Here, the turbine rotation speed Nt is the output shaft rotation speed No detected by the vehicle speed sensor 110 and A
It is obtained by calculating Nt = No × j from the gear ratio j detected by the / T computer 50, and the engine speed Ne is detected based on the signal from the crank angle sensor 108.

In an automatic transmission provided with a turbine speed sensor, the turbine speed Nt may be input from the turbine speed sensor.

Next, at step 206, the heat generation amount Q _{A / T} of the automatic transmission 100 is calculated as follows.

First, from the accelerator opening Θ obtained by the throttle sensor 104, the engine speed Ne obtained above, and the outside air temperature θamb detected by the intake air temperature sensor 102, a predetermined value is obtained as shown in the following equation (4). The engine torque Te is determined from the map of and the correction is made by the outside air temperature θamb.

Te = f ₂ (Ne, Θ, θamb) (4)

That is, the engine torque Te is the outside temperature θamb.
The amount of heat generation Q _{A / T} of the automatic transmission 100 cannot be ignored and, for example, as shown in FIG. 7, θ amb =
Assuming that the reference value Te 'according to the map is at 20 [° C.], when θamb = 0 [° C.], Te = Te ′ + Te1,
When θ amb = 35 [° C.], correction is performed as Te = Te′−Te2 (Te1 and Te2 are constants obtained from the map).

Next, as shown in the following equation (5), the engine torque Te, the engine speed Ne, and the gear stage k (k moves from the first gear stage to the overdrive (OD) stage) are shown in FIG. Automatic transmission efficiency η
_{A / T} is determined, and correction is made based on the engine speed Ne.

Η _{A / T} = f ₃ (Te, Ne, k) (5)

Here, the normal range (1000 [rpm] ≤N
When e ≦ 3000 [rpm]), the term of engine speed Ne can be omitted.

Further, α is a coefficient (for example, 2π / 60),
Further, the torque converter efficiency η obtained in step 204
_{Using T / C} , the heat generation amount Q _{A / T} of the automatic transmission 100 is calculated by the following equation (6).

Q _{A / T} = α ・ Te ・ Ne ・ (1-η _{T / C}・ η _{A / T} ) (6)

Next, in step 208, the oil cooler flow rate q _{O / C} and the oil cooler heat radiation amount Q _{O / C} are calculated.

The oil cooler flow rate q _{O / C} is determined by the following equation (7) based on the engine speed Ne, the accelerator opening Θ, and the previously estimated oil temperature θ _{A / Ti} of the automatic transmission 100. .

Q _{O / C} = f ₄ (Ne, Θ, θ _{A / Ti} ) (7)

For example, q _{O / C} is a constant when the following equation (8) Ne ≦ 1500 [rpm] and Θ ≦ 35 [%] (8) holds, and otherwise a and b are constants. Then, it is determined as in the following equation (9).

Q _{O / C} = a · θ _{A / Ti} −b (9)

Further, using this q _{O / C} , the reference value Q _{O / C} 'of the heat radiation amount Q _{O / C} of the oil cooler is obtained from the map, and further the engine cooling water temperature θ _W and the oil temperature θ _{A / Ti} are used. Next (1
Calculate the heat dissipation QO _{/ C} of the oil cooler from the equation 0).

Q _{O / C} = Q _{O / C} ′ · (θ _{A / Ti} −θ _W ) ... (10)

Here, the reference value Q _{O / C} ′ is a reference value obtained based on a certain temperature difference between the oil temperature θ _{A / Ti} and the engine cooling water temperature θ _W, and should be multiplied by the actual temperature difference. Therefore, the oil cooler heat radiation amount Q _{O / C} is obtained.

Next, at step 210, the automatic transmission equivalent heat transfer coefficient A and the heat radiation amount Q _{T / M} to the atmosphere are calculated.

The equivalent heat transfer coefficient A of the automatic transmission is determined by the vehicle speed v [km / h] when the engine cooling fan is a function of the engine speed as in the case where the vehicle is rear-wheel drive.
It is given by the following equation (11), where c and d are constants.

[0056] A = c + d · v [W / ° C] (11)

When the engine cooling fan is controlled by a motor or the like as in the case where the vehicle is driven by front wheels, the automatic transmission equivalent heat transfer coefficient A is determined according to the operation of the motor when the motor is not operating. A constant value is given, and when the motor is operating, the automatic transmission equivalent heat transfer coefficient A is given by the equation similar to the equation (11).

Further, in order to calculate the heat radiation amount Q _{T / M} to the atmosphere, first, the average of the outside air temperature θ amb and the engine cooling water temperature θ _W is corrected using the constant β as in the following equation (12), The ambient temperature θ air of the automatic transmission 100 is calculated.

[0059] _{θair = (θamb + θ W)} / 2-β ... (12)

Next, using the ambient temperature θ air, the automatic transmission equivalent heat transfer coefficient A, and the oil temperature θ _{A / Ti} estimated this time,
The heat radiation amount Q _{T / M} to the atmosphere is calculated by the following equation (13).

Q _{T / M} = A · (θ _{A / Ti} −θ air) (13)

Next, at step 212, the new estimated oil temperature θ _{A / Ti + 1} of the automatic transmission 100 is estimated using the values calculated in the steps so far.

In the equation (1), the oil temperature change rate dθ _{A / T} /
Replace dt with (θ _{A / Ti + 1} −θ _{A / Ti} ) / Δt, then θ _{A / T}
And C are the current estimated oil temperature θ of the automatic transmission 100, respectively.
_{Assuming A / Ti} and the equivalent heat capacity coefficient Ci, the following equation (14) is obtained.

Q _{A / T} = Q _{O / C} + A · (θ _{A / Ti} −θ air) + Ci (θ _{A / Ti + 1} −θ _{A / Ti} ) / Δt (14)

If this is solved for θ _{A / Ti + 1} , the following (1
Equation (5) is obtained, which gives a new estimated value θ of the oil temperature.
_{A / Ti + 1} is calculated.

Θ _{A / Ti + 1} = {Q _{A / T} −Q _{O / C} −A · (θ _{A / Ti} −θ air)} Δt / Ci + θ _{A / Ti} (15)

Next, at step 214, the new automatic transmission equivalent heat capacity coefficient C _{i + 1 is set} to the oil temperature change rate dθ _{A / T} / d.
Using t = (θ _{A / Ti + 1} −θ _{A / Ti} ) / Δt, the following (16)
Calculate by formula.

C _{i + 1} = f ₅ (dθ _{A / T} / dt) (16)

Finally, in step 216, the
Estimated oil temperature θ_{A / Ti}The new estimated oil temperature θ _{A / Ti + 1}Update with
Return to step 204.

As described above, according to the first control example of this embodiment,
Then, the heat generation amount Q of the automatic transmission 100 _{A / T}, Oil cooler
Heat dissipation Q_{O / C}, Amount of heat radiation to the surroundings of the automatic transmission Q_{T / M}Or
To the inside of the automatic transmission (oil temperature rise rate), automatic transmission
The oil temperature rise of the machine was known, and this oil temperature rise was estimated last time.
Oil temperature of automatic transmission θ_{A / Ti}By adding
Oil temperature of automatic transmission θ_{A / Ti + 1}Can be estimated.

Therefore, by estimating the oil temperature of the automatic transmission from the balance of the amount of heat, the accuracy of the oil temperature estimation of the automatic transmission under various environments can be improved.

The flowchart of FIG. 9 shows a second control example.

When the engine is restarted immediately after it is stopped, as in the first control example described above, the automatic transmission 100
If the initial value θ _{A / T0} of the oil temperature θ _{A / Ti} of is the outside air temperature θ amb, a large error occurs in the initial value. That is, since the oil temperature θ _{A / Ti} is still actually high, a problem may occur if control is continued with the initial value thus erroneously determined.

Therefore, in the second control example, when the engine is restarted immediately after being stopped, the automatic transmission 1
By estimating the initial values of the oil temperature θ _{A / Ti of} 00 and the equivalent heat capacity coefficient Ci so as to match the actual values, the accuracy of oil temperature estimation is further enhanced.

That is, the second control example is a step of determining whether or not the engine is restarted immediately after the engine is stopped after the engine is started, and an oil temperature θ when the engine is immediately restarted.
_A step of estimating initial values of _{A / Ti} and the equivalent heat capacity coefficient Ci is added.

When the engine is started in step 300 of FIG. 9, it is determined in the next step 301 whether or not a predetermined time has elapsed before the engine was started after the engine was stopped, and the predetermined time has not elapsed. In this case, it is determined that the engine was restarted immediately after it was stopped, and the initial values of the oil temperature θ _{A / Ti} and the equivalent heat capacity coefficient Ci are estimated in step 303.

[0077] Estimation of the initial value, after the engine is stopped, continuing to estimated oil temperature until the oil temperature theta _{A / Ti} is equal to or less than a predetermined oil temperature, the initial value of the oil temperature theta _{A / Ti} at restart It ensures accuracy.

That is, in the equation (15), it is considered that Q _{A / T} = Q _{O / C} = 0 because the vehicle is in a stopped state.
The formula is as shown in the following formula (17).

Θ _{A / Ti + 1} = −A (θ _{A / Ti} −θ air) Δt / C + θ _{A / Ti} (17)

However, the equivalent heat transfer coefficient A and the equivalent heat capacity coefficient C of the automatic transmission are set to predetermined values as initial values.

The A / T computer 50 which performs the calculation for continuing the estimation of the oil temperature θ _{A / Ti} even after the engine is stopped
Since it suffices to energize only the battery and the operation of the sensor and the like is unnecessary, the load on the battery is small and there is no problem.

As another method of estimating the initial value, the time t and the oil temperature θ _{A / Ti in} FIG. 10 are calculated from the outside air temperature when the engine is stopped.
It is also possible to give a slope γ of a graph showing the relationship of the above and continue the calculation of the oil temperature θ _{A / Ti} until a predetermined time elapses. This predetermined time is set to be longer as the outside air temperature is higher.

Here, the oil temperature θ _{A / Ti} is calculated by the following equation (18) using the oil temperature θ _{A / T} 'when the engine is stopped.

Θ _{A / Ti} = θ _{A / T} ′ −γ · t (18)

Further, the gradient γ should be decided in advance in several stages based on the above-mentioned initial value estimation method.

Further, in the flowchart of FIG. 9, the same steps as those of the flowchart of FIG. 5 in which the last two digits of the step number represent the first embodiment perform the same processing as the first control example, and the description thereof will be omitted. To do.

As described above, in the second control example of this embodiment, when the engine is restarted immediately after it is stopped, the oil temperature of the automatic transmission 100 is continuously estimated and estimated. Since the initial value of the oil temperature is used, the accuracy of the initial value at the time of restart can be secured.

An example of automatic transmission control using the oil temperature of the automatic transmission estimated by the above embodiment will be described.

For example, since the kinematic viscosity ν of the automatic transmission hydraulic oil decreases exponentially as the oil temperature θ _{A / T} increases, the oil passage resistance in the throttle portion in the hydraulic circuit is reduced. It depends oil temperature theta _{a / T,} since the oil fill time of clutches and brakes are different by the oil temperature theta _{a / T,} in all of the oil temperature range, it is impossible to optimally set the respective timer value of the speed change transients.

Therefore, a timer value corresponding to the oil temperature θ _{A / T} is given in advance by a map or calculation to achieve reduction of shift shock.

In addition, in order to avoid heat generation due to large slip of the torque converter at the i-th speed stage (where i ≠ 1), for example, when climbing a slope, when the oil temperature exceeds a predetermined value, the gear position is changed to the As the i-1 speed stage, the torque converter operates in a small slip range to lower the oil temperature.

When the oil temperature θ _{A / T} falls below a predetermined temperature, the i-th speed is restored. Alternatively, the normal (economy) mode is switched to the power mode.

By such control, it is possible to avoid an increase in the oil temperature of the automatic transmission without impairing the fuel consumption during normal traveling.

Further, for example, an automatic transmission with a snow mode (2
When the snow mode is mistakenly selected on a traffic jam road in the summer, the torque converter has a high slip ratio in the second speed stage. Air temperature θ amb, Oil temperature θ _{A / T}
When is above a predetermined value, this control is stopped and the driver is alerted by blinking the pattern display lamp or the like.

As described above, since the automatic transmission is controlled by using the accurately estimated oil temperature of the automatic transmission, it is possible to always perform appropriate control and improve the driving performance. it can.

[0096]

As described above, according to the present invention,
In various environments, it has become possible to accurately estimate the oil temperature of the automatic transmission.

[Brief description of drawings]

FIG. 1 is a block diagram showing the gist of the invention according to claim 1.

FIG. 2 is a block diagram showing the gist of the invention according to claim 2.

FIG. 3 is a block diagram showing the gist of the invention according to claim 3.

FIG. 4 is an overall schematic diagram showing an outline of an oil temperature estimation device for an automatic transmission to which the present invention is applied.

FIG. 5 is a flowchart showing a first control example according to this embodiment.

FIG. 6 is a diagram showing the relationship between speed ratio and torque converter efficiency.

FIG. 7 is a diagram showing the relationship between atmospheric temperature and engine torque.

FIG. 8 is a diagram showing the relationship between engine torque and automatic transmission efficiency.

FIG. 9 is a flowchart showing a second control example according to this embodiment.

FIG. 10 is a diagram showing the relationship between the time for estimating the oil temperature initial value and the oil temperature.

[Explanation of symbols]

40 ... Engine computer 50 ... A / T computer 100 ... Automatic transmission (A / T) 102 ... Intake air temperature sensor 104 ... Throttle sensor 106 ... Water temperature sensor 108 ... Crank angle sensor 110 ... Vehicle speed sensor

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) F16H 59/00-63/48 F16H 41

Claims (3)

(57) [Claims] Claim: What is claimed is: 1. An apparatus for estimating the oil temperature of an automatic transmission, comprising: heat generation amount calculating means for obtaining the heat generation amount of the automatic transmission from the engine output and the efficiency of the automatic transmission; A second heat radiation amount calculation means for obtaining a heat radiation amount, and a second heat radiation amount calculation for obtaining a heat radiation amount from the surface of the automatic transmission to the periphery of the automatic transmission from the estimated oil temperature of the automatic transmission and ambient temperature of the automatic transmission. Means and the heat generation amount of the automatic transmission, the value obtained by subtracting the heat radiation amount in the oil cooler and the heat radiation amount to the surroundings of the automatic transmission and the estimated oil temperature of the automatic transmission are used to determine the oil temperature of the automatic transmission An oil temperature estimating device for an automatic transmission, comprising: an oil temperature estimating means for newly estimating. 2. The method according to claim 1, wherein the second heat radiation amount calculation means and the oil temperature estimation means are provided with an atmospheric temperature as an initial value of the estimated oil temperature of the automatic transmission after the engine is started. Characteristic automatic transmission oil temperature estimation device. 3. The engine according to claim 1, wherein when the engine is stopped, the oil temperature of the automatic transmission when the engine is stopped is estimated from the estimated oil temperature of the automatic transmission and the ambient temperature of the automatic transmission. The calorific value calculating means and the oil temperature estimating means,
The oil temperature estimating device for an automatic transmission, wherein the estimated oil temperature of the automatic transmission after the engine is stopped is given as an initial value of the estimated oil temperature of the automatic transmission after the engine is started.