JP5378295B2 - Friction engagement element control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a more accurate temperature estimated value to be calculated by considering a contact width of a friction material in temperature estimate calculation of the friction material of a lock-up clutch (LC). <P>SOLUTION: When a surface temperature of a friction material 18 is computed by performing a heat balance calculation using heat capacity HC of portion M with which the friction material 18 come into contact, a temperature difference between the surface temperature of the friction material 18 and a hydraulic fluid temperature of LC, and a cooling rate by the hydraulic fluid and by computing rise rate of a temperature difference between the surface temperature of the friction material 18 per unit time and the hydraulic fluid temperature, the portion M which the friction material 18 contacts is divided into two or more sections Ln beforehand to compute a section heat capacity HCk corresponding to the section Lk concerned. Then, of a plurality of sections Lk, the section Lk belonging to a region W which generates heat with the contact of the friction material 18 is determined based on data concerning fastening degree of LC. Then, a heat balance is calculated for each corresponding section Lk and the surface temperature Tk is calculated using the section heat capacity HCk. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to a control device for a frictional engagement element that controls the engagement state of a frictional engagement element such as a lock-up clutch associated with a torque converter.

  A torque converter mounted on a vehicle is often provided with a lock-up clutch (LC) that directly connects the impeller and the turbine, and the engagement of the lock-up clutch improves power transmission efficiency and fuel consumption. In recent years, control for partially engaging a lockup clutch, that is, slip control of the lockup clutch is often performed for the purpose of further improving fuel consumption. However, if slip control is performed, the amount of heat generated by the friction material of the lock-up clutch increases, so that measures are required to ensure the durability of the friction material, the seal member, and the like. For this reason, various devices and methods have been proposed in order to protect the lockup clutch from heat generated by slipping.

  In this regard, Patent Document 1 discloses a control device for a torque converter with a lockup mechanism. This control device calculates the surface temperature of the clutch friction material in the lock-up clutch based on the hydraulic oil temperature in the torque converter and the heat generation amount of the lock-up clutch, and determines the surface temperature of the calculated clutch friction material in advance. When the surface temperature of the clutch friction material is determined to be equal to or higher than the allowable temperature by comparing with the allowable temperature, a predetermined operation for reducing the surface temperature of the clutch friction material is performed. According to this, since the surface temperature of the clutch friction material can be grasped and its rise can be suppressed, the durability of the clutch friction material can be ensured while performing the slip control of the lockup clutch.

  And in said control apparatus, the estimated value of the surface temperature of a clutch friction material is calculated. In calculating the surface temperature, the heat capacity of the portion sliding with the clutch friction material, the temperature difference of the hydraulic oil temperature in the torque converter with respect to the surface temperature of the clutch friction material, and the cooling rate by the hydraulic oil in the torque converter are used. Calculate the temperature difference change rate between the clutch friction material surface temperature per unit time and the hydraulic oil temperature in the torque converter, and calculate the clutch friction material surface temperature from this temperature difference change rate. To do.

Japanese Patent No. 3476718

  However, the friction material of an actual lock-up clutch does not always contact the entire converter cover evenly with respect to the converter cover on the other side, and often comes into contact with the surface slightly inclined. Therefore, the area where the friction material comes into contact with the converter cover (hereinafter sometimes referred to as “hit width”) changes stepwise in accordance with the clutch hydraulic pressure, the transmission torque, and the like. Thereby, even if the heat generation amount of the lock-up clutch is the same, if the contact width is small, the heat capacity of the heat receiving portion is small, so the temperature rise of the friction material increases. Also, when the engagement force (transmission torque) of the lock-up clutch is large, both the outer peripheral side and the inner peripheral side of the friction material come into contact with each other (contacting the entire surface), and the outer peripheral side and the inner peripheral side have substantially the same temperature. Although an increase can be obtained, when the fastening force is small, only the rotating outer peripheral side of the friction material comes into contact (per one piece), so that the temperature on the outer peripheral side of the friction material mainly increases. This is also confirmed by actual measurement of the temperature change of the friction material.

  For this reason, it is desirable to perform temperature estimation in consideration of friction material half-contact from the viewpoint of improving accuracy and protecting the temperature estimation of the friction material. However, as shown in Patent Document 1, although the temperature estimation of the friction material at the time of lock-up clutch engagement has already been performed, in this temperature estimation, the contact width of the friction material is always constant, and the temperature estimation target The estimation calculation was performed under the assumption that the heat capacity of the heat receiving part is constant.

  As described above, the prior art disclosed in Patent Document 1 has a problem in that the accuracy of temperature estimation is not necessarily high because it does not take into account the contact of the friction material. In particular, the temperature estimation at the time of low torque where the tendency to hit one side is remarkable has a large room for accuracy improvement. That is, in a state where the heat capacity of the heat receiving portion is small per friction material piece at a low torque (a state where the heat balance per unit mass is large), the estimated value of the temperature of the friction material is lower than the actual temperature. Therefore, there is a possibility that the reliability of protection of the lockup clutch and the durability of the lockup clutch are lowered.

  The present invention has been made in view of the above points, and in estimating the temperature of a friction material included in a friction engagement element such as a lock-up clutch, a more accurate temperature estimation value can be obtained by considering the contact width of the friction material. The purpose is to enable the calculation of.

  In order to solve the above problems, the present invention provides a friction engagement element control device (1) for controlling the engagement state of the friction engagement element (LC), the friction material included in the friction engagement element (LC). According to the surface temperature calculating means (8) for calculating the estimated value of the surface temperature of (18) and the surface temperature (T) of the friction material (18) calculated by the surface temperature calculating means (8), the friction engagement element Control means (8) for controlling the engagement state of (LC), and the surface temperature calculation means (8) includes a heat capacity (HC) of a portion (M) in contact with the friction material (18), and a friction material ( 18) the temperature difference (DT) between the surface temperature (T) of the friction engagement element (LC) and the hydraulic oil temperature (Tm) of the friction engagement element (LC), the cooling rate (t) of the friction engagement element (LC) by the hydraulic oil, Is used to calculate the heat balance, the surface temperature (T) of the friction material (18) per unit time and the friction engagement element (LC) When calculating the temperature difference change rate (ΔT) with the oil temperature (Tm) and calculating the surface temperature (T) of the friction material (18) from this temperature difference change rate (ΔT), the friction material (18) Is divided into a plurality of sections (Lk), a section heat capacity (HCk) corresponding to the section (Lk) is calculated, and then the friction engagement element (LC) Is obtained, and based on the data relating to the degree of fastening, the division (Lk) belonging to the region (W) that generates heat when the friction material (18) contacts is determined among the plurality of divisions. For each section (Lk) belonging to the region (W) to be performed, heat balance calculation is performed for each section (Lk) and the surface temperature (Tk) is calculated using the section heat capacity (HCk). And

  According to the friction engagement element control device according to the present invention, when calculating the surface temperature of the friction material, the portion in contact with the friction material is divided into a plurality of sections in advance, and the section heat capacity corresponding to the section is calculated. In addition, based on the data relating to the degree of engagement, the data belonging to the region that generates heat when the friction material comes into contact is determined based on the data relating to the degree of engagement. (The contact width of the friction material was determined), and for each section belonging to the region, the heat balance calculation was performed for each section and the surface temperature was calculated using the section heat capacity. Accordingly, in calculating the surface temperature of the friction material, the surface temperature can be calculated using the heat capacity of the region in consideration of the region that generates heat when the friction material actually hits. As a result, it is possible to estimate the temperature appropriately according to the contact width of the friction material, so that the temperature of the friction material included in the friction engagement element can be estimated with higher accuracy. In particular, in the conventional temperature calculation of the friction material, the calculation is performed on the assumption that the heat capacity of the portion in contact with the friction material is constant regardless of the size of the heat generation region (the hit width). Therefore, in a state where the contact width is small and the heat capacity of the heat receiving part is small, the actual surface temperature becomes higher than the estimated value, and there is a concern about sufficient protection of the friction material. On the other hand, in the method of the present invention, in the state where the fastening force of the friction engagement element is low (the pressing force is small), since the contact width of the friction material is small, the heat capacity of the heat generating region becomes small. Therefore, if the actual temperature is likely to rise, the estimated temperature rises with the same tendency, so that the surface temperature of the friction material can be accurately estimated. Therefore, the reliability of protection for the friction material and the friction engagement element can be improved.

  In the friction engagement element control device, the friction engagement element (LC) is a lock-up clutch (LC) associated with the torque converter (TC). TC) may be at least one of the indicated hydraulic pressure, transmission torque, and rotation speed data.

  The contact width of the friction material included in the friction engagement element such as a lock-up clutch is a function of the pressing force applied to the friction engagement element. Therefore, in the case of a lock-up clutch, the contact width of the friction material is determined by the command hydraulic pressure of the torque converter, the transmission torque, or the like. Further, the contact width of the friction material also changes when the shape of the converter cover changes in accordance with the rotational speed of the torque converter. Therefore, as described above, the data relating to the engagement strength for determining the section belonging to the region that generates heat when the friction material comes into contact is at least one of the indicated hydraulic pressure, transmission torque, and rotation speed data of the torque converter. It is desirable to be. This makes it possible to effectively monitor the temperature rise of the friction material due to slip control in a lock-up clutch that tends to cause non-uniformity (so-called one-side contact) in contact with the friction material, and to improve the reliability of protection of the lock-up clutch. Can be improved.

  In the friction engagement element control device, the surface temperature calculation means (8) prioritizes the pressing force of the friction material (18) against the plurality of sections (Ln) to generate heat. Among the sections (Lk) belonging to (W), the heat balance calculation is performed only for the section (Lh) where the pressing force of the friction material (18) is the strongest, and the surface temperature (Th) is calculated using the section heat capacity (HCh). ) May be calculated. Further, the section (Lh) for calculating the surface temperature (Th) in this case may be a section (Lh) including a position corresponding to the end (19) on the rotating outer peripheral side of the friction material (18).

When the friction material is in contact with each other, the portion that contacts with the strongest force usually receives the maximum heat, so that the highest temperature is reached. From the viewpoint of protecting the friction material and monitoring the load, it is sufficient to grasp the temperature of the highest temperature part. Therefore, as described above, if the surface temperature is calculated only for the section with the strongest pressing force of the friction material, the surface temperature calculation procedure can be simplified while ensuring the reliability of protection. Thus, the configuration of the control device can be simplified.
In addition, the code | symbol in said parenthesis shows the code | symbol of the component in embodiment mentioned later as an example of this invention.

  According to the friction engagement element control apparatus according to the present invention, in the temperature estimation calculation of the friction material included in the friction engagement element such as a lock-up clutch, the calculation accuracy of the estimated temperature value is considered by considering the contact width of the friction material. And the reliability of protection of the friction engagement element can be improved.

It is the fragmentary schematic sectional drawing which shows the torque converter with a lockup clutch to which this invention is applied, and the block diagram which shows the control apparatus. It is a flowchart (main flow) which shows the control content of the control apparatus of a lockup clutch. It is a flowchart which shows the subroutine of the load calculation of a lockup clutch. It is a figure which shows typically the surface of the site | part which a friction material contacts. It is a flowchart which shows the subroutine of the calculation procedure of friction material surface temperature. FIG. 4 is a schematic diagram showing a change in a heat generation region depending on a contact width of a friction material, in which (a) shows a state where the fastening force (pressing force) of the lockup clutch is small, and (b) shows a fastening force (pressing force) of the lockup clutch. It is a figure which shows a state with large. FIG. 9 is a schematic diagram showing a change in a heat generation region depending on a contact width of a friction material in a second embodiment of the present invention, where (a) shows a state where the fastening force (pressing force) of the lockup clutch is small, and (b) shows a lockup It is a figure which shows the state where the fastening force (pressing force) of a clutch is large. It is a figure which shows typically the surface of the site | part which a friction material contacts. It is a flowchart which shows the subroutine of the calculation procedure of the friction material surface temperature in 2nd Embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[First Embodiment]
FIG. 1 is a partial schematic cross-sectional view showing a torque converter with a lock-up clutch to which the present invention is applied, and a block diagram showing its control device. A torque converter TC shown in FIG. 1 is provided with an impeller 11 connected to an engine output shaft (not shown) via a converter cover 11a, an impeller 11 facing the impeller 11, and a transmission input shaft via a turbine hub 12a. It is comprised from the turbine 12 connected with (not shown) and the stator 13 fixedly hold | maintained. A lockup piston 15 is disposed in a space surrounded by the rear surface of the turbine 12 and the inner surface of the converter cover 11a. This space is divided into two by a lockup piston 15, a lockup release chamber 16 surrounded by the converter cover 11 a and the lockup piston 15, a lockup fastening chamber 17 surrounded by the turbine 12 and the lockup piston 15, and It is divided into. The lock-up piston 15 is axially movable with respect to the turbine hub 12a and is attached so as to rotate integrally with the turbine hub 12a.

  The operation of the lockup clutch LC is performed by controlling the hydraulic pressure in the lockup release chamber 16 and the lockup fastening chamber 17 by controlling the hydraulic pressure supplied from the lockup oil inlet 16a and the converter oil inlet 17a. . For example, by reducing the hydraulic pressure in the lockup release chamber 16, the lockup piston 15 is pressed against the inner surface of the converter cover 11 a by the hydraulic pressure in the lockup fastening chamber 17, and the clutch friction material provided on the side surface of the lockup piston 15. (Hereinafter, simply referred to as “friction material”.) The lock-up piston 15 and the converter cover 11a are coupled by friction between 18 and the inner surface of the converter cover 11a. As a result, the lockup operation state in which the impeller 11 and the turbine 12 are engaged and rotate together is achieved. On the contrary, when hydraulic oil is supplied from the lockup oil inlet 16a to the lockup release chamber 16 and the hydraulic pressure in the lockup release chamber 16 is higher than the hydraulic pressure in the lockup fastening chamber 17, the lockup piston 15 is The lockup is released away from the inner surface of the converter cover 11a, the impeller 11 and the turbine 12 can rotate independently, and the torque converter TC is activated.

  Thus, by controlling the hydraulic pressure supplied from the lockup oil inlet 16a and the converter oil inlet 17a, the contact between the lockup piston 15 and the inner surface of the converter cover 11a is controlled, and the lockup is activated. It can be released, or further partially engaged (this is referred to as slip control of the lockup clutch LC). In order to perform such lock-up control, a lock-up control device 1 is provided.

  The lock-up control device 1 is regulated by a hydraulic pump 5 that supplies hydraulic oil in the oil tank 6, a supply pressure adjusting unit 4 that adjusts a supply pressure supplied from the hydraulic pump 5, and a supply pressure adjusting unit 4. Hydraulic circuit switching means 3 for controlling the supply of the hydraulic oil to the lockup oil inlet 16a and the converter oil inlet 17a, and the fastening force adjustment for controlling the hydraulic pressure supplied from the lockup oil inlet 16a to the lockup release chamber 16 It comprises a means 2, a signal pressure generating means 7 for supplying a signal pressure for controlling the operation of the fastening force adjusting means 2, and a main controller 8 for giving a command to the signal pressure generating means 7. In this lockup control device 1, the hydraulic pressure in the lockup release chamber 16 is regulated by the fastening force adjusting means 2 based on the command of the main control unit 8, and the hydraulic pressure in the lockup fastening chamber 17 is adjusted to supply pressure. The engagement control of the lockup clutch LC is performed by controlling the pressure regulation by the means 4 and switching the supply hydraulic pressure by the hydraulic circuit switching means 3. The main control unit 8 functions as a surface temperature calculation unit that calculates an estimated value of the surface temperature of the friction material according to the present invention and a control unit that controls the engagement state of the friction engagement elements.

  When the engagement operation control of the lockup clutch LC is performed in this way (especially when slip control is performed), heat is generated by friction between the friction material 18 and the inner surface of the converter cover 11a, and the durability of the friction material 18 is improved. There is a risk of damage. For this reason, in the lockup control device 1 of the present invention, the main control unit 8 calculates the surface temperature of the friction material 18 and performs control for preventing the surface temperature from becoming excessively high. It has become.

  FIG. 2 is a flowchart (main flow) showing the above control contents. In this control, first, load calculation of the lock-up clutch LC is performed (step S1). A specific procedure for calculating the load of the lockup clutch LC will be described in detail below. Thereafter, the hydraulic oil temperature sensor detects the hydraulic oil temperature Tm of the torque converter (step S2). Then, the surface temperature T of the friction material 18 of the lockup clutch LC is calculated (step S3). The surface temperature T of the friction material 18 here is a surface temperature for each of the sections obtained by dividing the heat generation region of the portion in contact with the friction material 18 into a plurality of sections, as will be described later. A specific procedure for calculating the surface temperature will be described in detail below.

  And the present surface temperature T of the friction material 18 calculated | required above is compared with the allowable temperature T1 set according to the friction material 18 (step S4). As a result, when the current surface temperature T of the friction material 18 is less than the allowable temperature T1 (NO), the process returns to step S1 and the above-described procedure is continued. On the other hand, when the temperature is equal to or higher than the allowable temperature T1 (YES), control for reducing the temperature of the friction material 18 is performed (step S5). As control for lowering the temperature of the friction material 18 here, for example, control for completely engaging the lock-up clutch LC or control for completely releasing the lock-up clutch LC is performed. As a result, the state where the surface temperature of the friction material 18 is equal to or higher than the allowable temperature T1 is eliminated, so that the expected durability of the friction material 18 can be ensured.

Here, the procedure of load calculation (step S1) of the lockup clutch LC will be described. FIG. 3 is a flowchart showing a subroutine for calculating the load of the lockup clutch LC. In this load calculation, first, the engine throttle opening θ _TH is detected by the throttle opening sensor, and the vehicle speed V is detected by the vehicle speed sensor (step S1-1). Based on these detection values, a target slip ratio in the lockup slip control is calculated (step S1-2), and the engagement control of the lockup clutch LC is performed so as to obtain such a target slip ratio (step S1-). 3). At this time, the engine speed Ne (ie, the torque converter input speed) and the transmission input speed Nm (ie, the torque converter output speed) are detected (step S1-4).

Further, the engine output torque is estimated based on the engine throttle opening θ _TH and the engine speed Ne (step S1-5). Then, the lockup clutch transmission torque _TLC and the lockup clutch differential rotation ΔN are calculated (step S1-6). Calculation of the lockup clutch transmission torque _TLC and the lockup clutch differential rotation ΔN is performed in the following procedure.

First, the lockup clutch differential rotation ΔN is the difference between the engine speed Ne and the transmission input speed Nm. On the other hand, with respect to the lockup clutch transmission torque _TLC , when the lockup clutch LC is performing the slip control, the engine torque Te is the sum of the lockup clutch transmission torque _TLC and the fluid transmission torque _TTC of the torque converter. Is expressed as the following equation (1). Here, the fluid transmission torque T _TC of the torque converter is obtained by the following equation (2) using the capacity coefficient τ of the torque converter obtained from the engine speed Ne and the transmission input speed Nm (or the target slip ratio). It is done. From these equations (1) and (2), the lockup clutch transmission torque _TLC is obtained.

Te = _TLC + _TTC (1)
T _TC = τ · (Ne / 1000) ² ··· (2)

  Next, the procedure for calculating the surface temperature of the friction material 18 (step ST3) will be described. In the present embodiment, when the surface temperature of the friction material 18 is calculated, the portion of the converter cover 11a that is in contact with the friction material 18 is divided into a plurality of sections, and the section heat capacity corresponding to the section is calculated. It has become. FIG. 4 is a diagram for explaining this, and is a diagram schematically showing the surface of the portion M with which the friction material 18 comes into contact. In the same figure, the distribution of the radial direction of the part M which the friction material 18 touches on the vertical axis | shaft is taken. Here, the whole LA of the part M in contact with the friction material 18 is divided into a plurality of (here, n) sections L1, L2,... Ln in the radial direction. Then, the section heat capacities HC1, HC2,... HCn corresponding to the plurality of sections L1, L2,. Note that the entire LA of the part M in contact with the friction material 18 is the maximum value of a region (heat generation region) W where heat is generated by the contact of the friction material 18, and the heat capacity HC = ΣHCk (k = 1 to n) is This is the maximum heat capacity corresponding to the maximum value of the heat generation area W.

FIG. 5 is a subroutine showing a procedure for calculating the surface temperature of the friction material 18. This operation, first, the lock-up clutch transmission torque T _LC and loading the lock-up clutch differential rotation .DELTA.N (step S3-1), calculates the calorific value Q _LC of the lock-up clutch LC (step S3-2). The calorific value Q _LC of the lockup clutch LC is obtained by the following equation (3).

Q _LC = T _LC · (π / 30) · ΔN · dt ··· (3)

  Subsequently, the hydraulic oil temperature Tm in the torque converter TC is read (step S3-3). And the data regarding the pressing force (engagement degree) of the lockup clutch LC is acquired (step S3-4). As the data relating to the pressing force of the lockup clutch LC here, at least one of the command hydraulic pressure of the torque converter, the transmission torque, and the rotational speed can be used. Based on these data, the pressing force of the lockup clutch LC can be grasped. Based on the pressing force of the lock-up clutch LC, the contact location and contact width of the friction material 18 are calculated (step S3-5). Specifically, the calculation of the contact location and the contact width of the friction material 18 is performed by dividing the plurality of sections L1, L2,... Ln into a region (heat generation region) W that generates heat when the friction material 18 contacts. This is done by determining the number and position of Lk.

  6A and 6B are schematic diagrams showing changes in the heat generation region W depending on the contact width of the friction material 18, where FIG. 6A shows a state where the fastening force (pressing force) of the lock-up clutch LC is small, and FIG. 6B shows a lock-up clutch. It is a figure which shows the state with large fastening force (pressing force) of LC. As described above, the friction member 18 of the lock-up clutch LC does not always contact the converter cover 11a evenly, and the surface area (contact per contact) depends on the pressing force of the lock-up clutch LC. Width) changes. Specifically, in a state where the pressing force of the lock-up clutch LC is small, only the end on the outer diameter side or a part of the vicinity thereof abuts (a one-sided state), and the pressing force increases from there. The abutting area expands step by step. Therefore, as shown in FIG. 10A, when the fastening force (pressing force) of the lock-up clutch LC is small, the heat generation area W is small and the number of sections Lk belonging to it is small. As shown, when the fastening force (pressing force) of the lock-up clutch LC increases, the heat generation area W expands, and the number of sections Lk belonging to it increases. Therefore, the heat capacity HCk of the heat generation region W can be calculated by determining the number and positions of the sections Lk belonging to the heat generation region W. The change in the heat generation region W with respect to the pressing force of the lockup clutch LC is determined based on the measured value of the temperature change of the friction material 18 measured in advance.

  Next, heat balance calculation is performed for each section Lk determined above (step S3-6). This heat balance is calculated by the following equation (4).

ΔQk ← (Qk_in−Qk_out) * Ak = (Q _LC −t · DT) * Ak (4)

However, Ak: Coefficient for assigning the heat generation amount of the entire heat generation region to each section t: Cooling rate correction coefficient by hydraulic oil DT: Temperature difference between friction material surface temperature Tk and hydraulic oil temperature Tm

The coefficient Ak is a coefficient for assigning the heat generation amount of the entire heat generation region W to each section Ln in consideration of the contact location and contact width of the friction material 18 determined according to the pressing force of the current lockup clutch LC. is there. This coefficient Ak is determined based on the measured value of the temperature change of the friction material 18 measured in advance. Further, in the calculation in the equation (4), Q _LC = 0 and Tk = Tm are set as initial conditions.

  Further, based on the calculated heat balance, a temperature difference change rate ΔTk between the friction material surface temperature Tk and the hydraulic oil temperature Tm per unit time in each section Lk is calculated (step S3-7). This temperature difference change rate ΔTk can be calculated by the following equation (5).

ΔTk ← ΔQk / HCk (5)
(K = 1, 2,... N)

  Next, from the calculated temperature difference change rate ΔTk of each section Lk and the surface temperature Tk of each section Lk obtained by the previous calculation, the current surface temperature Tk ′ of each section Lk is expressed by the following equation (6). Obtained (step ST3-8). Hereinafter, this calculation is repeated, and the surface temperature Tk ′ of the friction material 18 of each section Lk that changes every moment can be obtained.

Tk ′ = Tk + ΔT (6)
(K = 1, 2,... N)

  The comparison between the current surface temperature T and the allowable temperature T1 of the friction material 18 performed in step S4 in FIG. 2 is the highest temperature among the surface temperatures Tk ′ (k = 1, 2,...) Of each section. And the allowable temperature T1.

  As described above, in the control device for the lockup clutch of the present embodiment, when calculating the surface temperature of the friction material 18, the part M with which the friction material 18 is contacted in advance is divided into a plurality of sections L1, L2,. After dividing, the section heat capacities HC1, HC2,... HCn corresponding to the sections L1, L2,..., Are calculated, and then data relating to the degree of engagement of the lockup clutch LC is acquired and the engagement is performed. Based on the degree-related data, a section Lk belonging to the heat generation region W that generates heat when the friction material 18 comes into contact is determined among the plurality of sections L1, L2,... Ln. The heat balance was calculated for each time and the surface temperature Tk was calculated using the section heat capacity HCn. Therefore, in the calculation of the surface temperature of the friction material 18, the size of the heat generation area W that generates heat when the friction material 18 actually hits the portion M in contact with the friction material 18 is considered. The surface temperature Tk can be calculated using only the heat capacity HCk of the section Lk to which it belongs. As a result, appropriate temperature estimation according to the contact width of the friction material 18 can be performed, so that the temperature of the friction material 18 of the lockup clutch LC can be estimated with high accuracy.

  In the conventional temperature calculation of the friction material, the calculation is performed on the assumption that the heat capacity of the portion in contact with the friction material is constant regardless of the size of the heat generation region (the hit width). For this reason, in a state where the contact width is small and the heat capacity of the portion in contact with the friction material is small, the actual surface temperature becomes higher than the calculated value, and there is concern about protection of the friction material 18. On the other hand, according to the method of the present embodiment, in the state where the fastening force of the lockup clutch LC is low (the pressing force is small), the contact width of the friction material 18 is small, so the section Lk belonging to the heat generation region W The heat capacity HCk of becomes smaller. Therefore, if the actual temperature is likely to rise, the estimated value also rises with the same tendency, so that the surface temperature of the friction material 18 can be estimated with higher accuracy than before. Therefore, the reliability of protection of the friction material 18 can be improved.

  Further, the contact width of the friction material 18 of the lockup clutch LC is a function of the pressing force applied to the lockup clutch LC. For this reason, the contact width of the friction material 18 is determined by the indicated hydraulic pressure of the lockup clutch LC or the transmission torque. Further, the contact width of the friction material 18 also changes when the shape of the converter cover 11a changes according to the rotational speed of the torque converter TC. Therefore, as described above, the data relating to the degree of engagement of the lockup clutch LC used to determine the section Lk belonging to the heat generation region W that generates heat when the friction material 18 is in contact includes the command hydraulic pressure, the transmission torque, It is desirable that the rotation speed data is at least one of them. Thereby, in the lock-up clutch LC in which non-uniformity (so-called one-side contact) is likely to occur in the contact of the friction material 18, it is possible to appropriately monitor the temperature rise of the friction material 18 due to the slip control. Can be improved.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In the description of the second embodiment and the corresponding drawings, the same or corresponding components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted below. In addition, matters other than those described below are the same as those in the first embodiment. This is the same in other embodiments.

  FIG. 7 is a schematic diagram showing a change in the heat generation region W due to the contact width of the friction material 18 in the second embodiment, where (a) is a state where the fastening force (pressing force) of the lockup clutch LC is small, and (b). These are figures which show the state where the fastening force (pressing force) of lockup clutch LC is large. FIG. 8 is a diagram schematically showing the surface of the part M with which the friction material 18 comes into contact.

  In an actual lock-up clutch LC, the friction material 18 has an outer edge 19 on the outer peripheral side as shown in FIG. 7A when the fastening force of the lock-up clutch LC is small with respect to the inner surface of the converter cover 11a. Only the area including the area (shaded area in the figure) hits. As the fastening force (pressing force) of the lock-up clutch LC increases, as shown in FIG. 5B, the region including the outer peripheral side edge 19 that contacts one side increases toward the inner peripheral side. In this case, the strength of the force with which the friction material 18 comes into contact is the strongest at the position corresponding to the end 19 on the outer peripheral side, and gradually becomes weaker from the position toward the inner peripheral side. Accordingly, the distribution of the surface temperature of the heat generating region W is the highest temperature at the position corresponding to the outer edge 19 and gradually becomes lower as it goes to the inner circumference.

  From the viewpoint of protecting the friction material 18, it is sufficient to grasp only the highest surface temperature. Therefore, in the present embodiment, as shown in FIG. 8, the surface temperature is calculated only for the section Lh including the position corresponding to the end 19 on the outer peripheral side where the force with which the friction material 18 abuts is strongest. ing.

  Hereinafter, the calculation procedure of the surface temperature of the friction material 18 in the present embodiment will be specifically described. In the first embodiment, when the surface temperature calculation of the friction material 18 is performed, the part M in contact with the friction material 18 is divided in advance into a plurality of sections L1, L2,... Ln, and the sections L1, L2,. In the present embodiment, the heat capacity HC1, HC2,..., HCn is calculated, but in this embodiment, the section Lh that includes the position corresponding to the edge 19 on the outer peripheral side in the portion M that the friction material 18 contacts. It is sufficient to calculate only the heat capacity HCh.

  FIG. 9 is a flowchart showing a subroutine of the calculation procedure of the friction material surface temperature in the present embodiment. The flowchart of FIG. 9 corresponds to FIG. 5 of the first embodiment, and steps S33-1 to S33-4 are the same as steps S3-1 to S3-4 of the flowchart shown in FIG. The description is omitted.

  In the present embodiment, the heat balance calculation is performed only for the section Lh including the position corresponding to the outer edge 19 in the heat generation region W of the part M in contact with the friction material 18 (step S33-5). This heat balance is calculated by the following equation (7).

ΔQh ← (Qh_in−Qh_out) * Ah = (Q _LC −t · DT) * Ah · (7)
However,
Ah: coefficient for assigning the amount of heat generated in the entire heat generating area to the section Lh including the position corresponding to the outer edge 19

  The coefficient Ak is a coefficient for assigning the heat generation amount of the entire heat generation region W of the friction material 18 to the section Lh including the position corresponding to the outer edge 19 according to the current pressing force of the lockup clutch LC. It is. This coefficient is a coefficient determined based on the measured value of the temperature change of the friction material 18 measured in advance.

  Furthermore, based on the heat balance calculated above, the temperature difference change rate ΔTh between the friction material surface temperature per unit time and the hydraulic oil temperature Tm in the section Lh is calculated (step S33-6). This temperature difference change rate ΔT can be calculated by the following equation (8).

ΔTh ← ΔQh / HCh (8)

  Next, from the calculated temperature difference change rate ΔTh of the section Lh and the surface temperature Th of the friction material 18 of the section Lh obtained by the previous calculation, the surface temperature Th ′ of the current section Lh is expressed by the following equation (9). (Step ST33-7). Thereafter, this calculation can be repeated to determine the surface temperature Th of the section Lh that changes every moment.

Th '← Th + ΔTh ·· (9)

  The current surface temperature Th ′ thus calculated is compared with the allowable temperature T1 (corresponding to step S4 of the first embodiment).

  In the case where the frictional member 18 is in contact with each other, the portion that is in contact with the strongest force receives the maximum heat, so that the highest temperature is reached. From the viewpoint of protecting the friction material 18 and monitoring the load, it is sufficient to grasp the temperature at the highest temperature of the friction material 18. Therefore, if the surface temperature Th is calculated only in the section Lh where the pressing force of the friction material 18 is the strongest as described above, the friction material 18 is secured while ensuring the reliability of protection of the lockup clutch LC. Because the surface temperature calculation procedure can be simplified, the configuration of the control device 1 can be simplified.

  In the friction material 18 of the lock-up clutch LC, the section Lh including the position corresponding to the end 19 on the outer peripheral side is in contact with the strongest force, and thus has the highest temperature. Therefore, if the temperature Th of the section Lh including the position corresponding to the outer edge 19 is calculated as described above, the temperature rise of the friction material 18 due to the slip control can be effectively monitored. The reliability of protection can be secured.

  Note that here, only the surface temperature Th of the section Lh including the position corresponding to the outer edge 19 is considered in consideration of the aspect in which the friction material 18 is one-sided from the position corresponding to the outer edge 19. Although the case of calculation is shown, when the contact of the friction material 18 occurs in another manner, the section for measuring the surface temperature may be a section other than the above. That is, generally, the pressing force of the friction material 18 is ranked in advance with respect to the plurality of sections L1, L2,... Of the sections L1, L2,... Ln, the surface temperature can be calculated for the section where the pressing force of the friction material 18 is the strongest.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea described in the claims and the specification and drawings. Is possible. For example, the frictional engagement element using the control device according to the present invention is not limited to the lock-up clutch LC attached to the torque converter TC shown in the above embodiment, but may be a general gear stage setting clutch or brake. This type of friction engagement element may be used.

1 Lock-up control device 8 Main control part (surface temperature calculation means, control means)
11a Converter cover 15 Lock-up piston 18 Friction material HC Heat capacity HC1, HC2... HCn Section heat capacity L1, L2... Ln Section LA Whole surface LC Lock-up clutch M Part where friction material contacts TC Torque converter W Heat generation area

Claims (4)

A friction engagement element control device for controlling an engagement state of a friction engagement element,
Surface temperature calculation means for calculating an estimated value of the surface temperature of the friction material included in the friction engagement element, and an engagement state of the friction engagement element according to the surface temperature of the friction material calculated by the surface temperature calculation means Control means for controlling
The surface temperature calculating means includes
The heat balance using the heat capacity of the portion where the friction material contacts, the temperature difference between the surface temperature of the friction material and the hydraulic oil temperature of the friction engagement element, and the cooling rate by the hydraulic oil of the friction engagement element. A calculation is performed to calculate a temperature difference change rate between the surface temperature of the friction material per unit time and the hydraulic oil temperature of the friction engagement element, and the surface temperature of the friction material is calculated from the temperature difference change rate. When
Dividing the entire part in contact with the friction material in advance into a plurality of sections, calculating a section heat capacity corresponding to the section,
Obtain data on the degree of engagement of the friction engagement element, and based on the data on the degree of engagement, determine a section belonging to the region that generates heat by contacting the friction material among the plurality of sections,
The friction engagement element control device according to claim 1, wherein the heat balance calculation is performed for each section belonging to the heat generating region and the surface temperature is calculated using the section heat capacity. The friction engagement element is a lock-up clutch associated with the torque converter;
2. The friction engagement element control device according to claim 1, wherein the data relating to the degree of engagement is at least one of data on an instruction hydraulic pressure, a transmission torque, and a rotation speed of the torque converter. The surface temperature calculating means includes
Prioritizing the pressing force of the friction material for the plurality of sections,
Of the sections belonging to the heat generating region, the heat balance calculation is performed only for the section having the strongest pressing force of the friction material, and the surface temperature is calculated using the section heat capacity. The control device for a frictional engagement element according to claim 1 or 2. The friction engagement element control device according to claim 3, wherein the section for calculating the surface temperature is a section corresponding to a position including an end of the friction material on a rotating outer peripheral side.

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