JP5951287B2 - Power unit protection control device - Google Patents

Description

  The present invention detects the temperature of a power unit including a drive source and an automatic transmission, and when the detected temperature is equal to or higher than a predetermined value, the transmission gear ratio of the automatic transmission is changed from the current gear ratio to the high speed side or low speed side gear ratio. The present invention relates to a protection control device for a power unit that is changed to prevent overheating.

  In a vehicle equipped with an automatic transmission, if the coolant temperature of the engine exceeds a predetermined value or the oil temperature of the automatic transmission exceeds a predetermined value, the transmission ratio of the automatic transmission decreases (shifts up). Japanese Patent Application Laid-Open No. 2004-151867 discloses that the engine and automatic transmission are prevented from being overheated by changing the rotational speed of the engine.

JP-A-62-286847

  However, the above conventional one does not disclose how much the transmission ratio of the automatic transmission is reduced when there is a possibility of overheating. For example, the transmission ratio of the automatic transmission is reduced to OD (Over Drive). If this happens, the following problems occur.

  In other words, if the transmission ratio of the automatic transmission is reduced to OD while the vehicle is traveling uphill, not only will the vehicle speed decrease due to a significant decrease in driving force, but the engine brake will hardly be applied when shifting to downhill driving. Since it does not work, there is a problem that the foot brake load increases.

  Further, since the engine cooling water pump and the automatic transmission oil pump rotate at a rotation speed proportional to the engine rotation speed, the cooling water discharge flow rate and the oil discharge flow rate also change in proportion to the engine rotation speed. Cooling water discharged from the cooling water pump is supplied to the radiator to be cooled, and oil discharged from the oil pump is supplied to the oil cooler to be cooled, but when the engine rotation speed is reduced, the flow rate of cooling water or oil decreases. As a result, overheating of the engine and automatic transmission may increase.

  In order to avoid such a problem, it is conceivable to increase the cooling performance by increasing the size of the radiator or the oil cooler, but as a result, the cost, weight, dimensions, etc. increase, which is difficult to realize. Therefore, in order to suppress overheating of the power unit including the engine and the automatic transmission, it is important to change the transmission ratio of the automatic transmission.

  The present invention has been made in view of the above circumstances, and an object thereof is to reliably suppress overheating of a power unit including an engine and an automatic transmission.

In order to achieve the above object, according to the first aspect of the present invention, the temperature of the power unit including the drive source and the automatic transmission is detected, and when the detected temperature is equal to or higher than a predetermined value, the shift of the automatic transmission is changed. In a power unit protection control device for preventing overheating by changing the ratio from the current gear ratio to the high speed side or the low speed side gear ratio, a calorific value calculating means for calculating a calorific value of the power unit, and a heat dissipation amount of the power unit A heat dissipation amount calculating means for calculating, a rotation speed calculating means for calculating a rotation speed of the drive source in which the heat generation amount calculated by the heat generation amount calculating means is equal to the heat dissipation amount calculated by the heat dissipation amount calculating means, and acceleration of the vehicle with sometimes determines the rotational speed calculation means capable of maintaining the rotational speed is calculated gear ratio, the vehicle And determining the gear ratio determining means for rotational speed sustainable transmission ratio lower than the rotational speed when fast while shifting the automatic transmission to the speed ratio where the transmission ratio determining means determines the temperature predetermined value A power unit protection control device is provided, characterized by comprising a shift control means for maintaining the gear ratio until the ratio becomes less than.

  The drive source of the present invention corresponds to the engine E of the embodiment.

According to the configuration of the first aspect, the temperature of the automatic transmission connected to the drive source is detected, and when the detected temperature is equal to or higher than a predetermined value, the transmission ratio of the automatic transmission is changed from the current transmission ratio to the high speed side or the low speed side. The gear ratio is changed to prevent overheating. At this time, the heat generation amount calculation means and the heat dissipation amount calculation means respectively calculate the heat generation amount and the heat dissipation amount of the power unit, and the rotation speed calculation means calculates the rotation speed of the drive source at which the heat generation amount becomes equal to the heat dissipation amount , thereby determining the gear ratio. The means determines the transmission ratio of the automatic transmission based on the rotational speed , and the transmission control means shifts the automatic transmission to the transmission ratio and maintains the transmission ratio until the temperature becomes less than the predetermined value. The driving force of the power unit can be secured to the maximum while reliably suppressing overheating of the power unit. In addition, since a large-capacity radiator and oil cooler are not required, an increase in cost, weight, and dimensions can be prevented.

In particular, the gear ratio determining means determines the gear ratio at which the rotational speed calculated by the rotational speed calculating means can be maintained when the vehicle is accelerated, so that the driving force can be ensured to the maximum while suppressing overheating of the power unit. . Also, when the vehicle decelerates, the engine heat generation is small, so the engine speed can be set to a higher speed than when accelerating, but if controlled in this way, when the accelerator pedal is depressed for acceleration from the decelerated state If the engine speed is decreased and the accelerator pedal is returned, the engine speed may increase, which may cause the driver to feel uncomfortable. However, since the gear ratio determining means determines a gear ratio at which the rotational speed lower than the rotational speed can be maintained when the vehicle is decelerated, it is possible to eliminate the driver's uncomfortable feeling.

The figure which shows the whole structure of the protection control apparatus of a power unit. The block diagram of an electronic control unit. The flowchart of a main routine. The flowchart of the subroutine of step S2 of the main routine. Explanatory drawing of the method of calculating | requiring the engine speed which prevents overheating from the emitted-heat amount and the emitted-heat amount. Explanatory drawing of the effect of this invention with respect to the conventional continuously variable automatic transmission. Explanatory drawing of the effect of this invention with respect to the conventional multistage automatic transmission. The time chart which shows an example of protection control of a power unit.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the vehicle of the present embodiment includes a power unit P in which an engine E and an automatic transmission T are integrated. The automatic transmission T is an automatic transmission such as a belt type continuously variable transmission. The cooling water of the engine E is pumped up by the cooling water pump 11 and cooled by the radiator 12, and then passes through the oil cooler 13 to cool the oil and passes through the water jacket to cool the engine E. The automatic transmission T includes a transmission main body 24 and a torque converter 14, a pump impeller 15 of the torque converter 14 is connected to a crankshaft 16 of the engine E, and a turbine runner 17 is connected to a belt via an input shaft 18 of the transmission main body 24. It is connected to a speed change mechanism 19 composed of a continuously variable transmission mechanism. The oil in the automatic transmission T is pumped up from the oil pan 21 by the oil pump 20 connected to the pump impeller 15 and is supplied to the transmission main body 24 and the torque converter 14 via the hydraulic control valve 22. It is cooled by the oil cooler 13 and returned to the oil pan 21.

  The electronic control unit U includes a coolant temperature sensor Sa that detects the coolant temperature of the engine E, a first oil temperature sensor Sb that detects the oil temperature of the engine E, and a second that detects the oil temperature of the automatic transmission T. An oil temperature sensor Sc, an outside air temperature sensor Sd for detecting the outside air temperature, a surface temperature sensor Se for detecting the surface temperature of the transmission body 24, an engine rotation speed sensor Sf for detecting the engine rotation speed, and the transmission body 24 An input shaft rotational speed sensor Sg for detecting the input shaft rotational speed, a vehicle speed sensor Sh for detecting the vehicle speed, and an accelerator pedal opening sensor Si for detecting the accelerator pedal opening are connected. The electronic control unit U controls the transmission ratio of the automatic transmission T through the transmission mechanism 19 including the hydraulic control valve 22 and the belt type continuously variable transmission mechanism based on the detection values of the sensors Sa to Si. Control for suppressing overheating of the power unit P is executed.

  As shown in FIG. 2, the electronic control unit U includes an overheat determination unit M1, a heat generation amount calculation unit M2, a heat release amount calculation unit M3, a rotation speed calculation unit M4, a gear ratio determination unit M5, and a shift control unit. M6.

  The cooling water temperature sensor Sa, the first oil temperature sensor Sb, and the second oil temperature sensor Sc are connected to the overheat determination means M1. An engine rotation speed sensor Sf, an input shaft rotation speed sensor Sg, and a vehicle speed sensor Sh are connected to the heat generation amount calculation means M2, and an output torque Te of the engine E that is ECU information is further input. A cooling water temperature sensor Sa, a first oil temperature sensor Sb, a second oil temperature sensor Sc, an outside air temperature sensor Sd, a surface temperature sensor Se, an engine rotation speed sensor Sf, and a vehicle speed sensor Sh are connected to the heat radiation amount calculation means M3. The The rotation speed calculation means M4 is connected to an overheat determination means M1, a heat generation amount calculation means M2 and a heat release amount calculation means M3, and the gear ratio determination means M5 is connected to the rotation speed calculation means M4, a vehicle speed sensor Sh and an accelerator pedal opening sensor Si. Is connected, and a gear ratio determination means M5 and a hydraulic control valve 22 are connected to the speed change control means M6.

  Next, the operation of the embodiment of the present invention having the above configuration will be described.

  In step S1 of the flowchart of FIG. 3, the oil temperature Tm of the automatic transmission T is detected by the second oil temperature sensor Sc, the oil temperature To of the engine E is detected by the first oil temperature sensor Sb, and the cooling water temperature sensor Sa is detected. The coolant temperature Tw of the engine E is detected. In subsequent step S2, when the oil temperature Tm is equal to or higher than the threshold value Tmcs, the oil temperature To is equal to or higher than the threshold value Tocs, or the cooling water temperature Tw is equal to or higher than the threshold value Twcs, that is, at least one of the above three conditions is satisfied. In this case, it is determined that the power unit P is overheated, and the process proceeds to step S3. The step S1 and the step S2 are executed in the overheat determination means M1.

  The flowchart of FIG. 4 shows the subroutine of step S2. In step S11, the oil temperature Tm of the automatic transmission T is Tm ≧ Tmws. Otherwise, the oil temperature To of the engine E is To in step S12. If ≧ Tows and otherwise, if the cooling water temperature Tw of the engine E is Tw ≧ Twws in step S13, it is determined in step S14 that the power unit P is about to be overheated, and a high temperature warning is output. The high temperature warning is notified to the driver using, for example, a lamp, a chime, a voice, or the like.

  In step S15, if the oil temperature Tm of the automatic transmission T is Tm ≧ Tmcs, and if not, the oil temperature To of the engine E is To ≧ Tocs in step S16, and if not, the engine in step S17. When the cooling water temperature Tw of E is Tw ≧ Twcs, it is determined that the power unit P has overheated, and control is performed by changing the transmission ratio of the automatic transmission T to suppress overheating in step S18.

  The high temperature warning threshold values Tmws, Tows, and Twws are set smaller than the overheat suppression control threshold values Tmcs, Tocs, and Twcs.

  Returning to the flowchart of FIG. 3, in step S3, the vehicle state is detected by the outside air temperature sensor Sd, the surface temperature sensor Se, the engine rotation speed sensor Sf, the input shaft rotation speed sensor Sg, the vehicle speed sensor Sh, and the accelerator pedal opening sensor Si. In step S4, it is assumed that the throttle opening is WOT (full opening). The reason why the throttle opening is assumed to be WOT is that the power unit P generates the most heat in WOT.

  In subsequent step S5, the heat generation amount of the automatic transmission T is calculated by the heat generation amount calculation means M2. The heat generation amount of the automatic transmission T is given by the sum of the heat generation amount of the torque converter 14 (hereinafter sometimes referred to as TC) and the heat generation amount of the transmission main body 24.

TC calorific value is
TC heating value = engine output * (1-TC efficiency / 100) * time
= Te * Ne * (1-TC efficiency / 100) * time. Te is the output torque of the engine E and is information obtained from the engine ECU. The engine rotation speed Ne is information obtained from the engine rotation speed sensor Sf. The TC efficiency is stored in advance as map data, and a map search is performed using the speed ratio (Nin / Ne) of the torque converter 14 as a parameter. Nin is the input shaft rotation speed of the automatic transmission T, and is information obtained from the input shaft rotation speed sensor Sg.

The heat generation amount of the transmission body is
Transmission body heat generation = Transmission body inlet output * (1-Transmission body efficiency / 100) * Time
= Te * TC torque ratio * Nin * (1-transmission body efficiency / 100) * given in time. The transmission main body efficiency is preliminarily converted into map data and is obtained from the operating point. The TC torque ratio is stored in advance as map data, and is searched using the speed ratio (Nin / Ne) of the torque converter 14 as a parameter.

  The amount of heat generated by the engine E can also be obtained in the same manner as the amount of heat generated by the automatic transmission T described above.

  In subsequent step S6, the heat dissipation amount of the automatic transmission T is calculated by the heat dissipation amount calculation means M3. The heat dissipation amount of the automatic transmission T is given by the sum of the air heat dissipation amount and the cooler heat dissipation amount.

  The amount of heat released in the air is preliminarily converted into map data. The difference between the surface temperature of the transmission main body 24 detected by the surface temperature sensor Se and the outside air temperature (that is, the ambient temperature) detected by the outside air temperature sensor Sd and the vehicle speed sensor Sh. It is obtained from the obtained vehicle speed (ie, wind speed). The surface temperature of the transmission main body 24 can be replaced with a drain temperature. The cooler heat release amount is preliminarily converted into map data, and is obtained from the cooler oil temperature, the cooler water temperature, the cooler hydraulic oil flow rate, and the cooler coolant flow rate. The hydraulic oil flow rate of the cooler and the cooling water flow rate of the cooler may be obtained in advance as map data and obtained from the operating point. The cooler oil temperature may be substituted by the drain oil temperature, and the cooler water temperature may be substituted by the cooling water temperature.

  The heat dissipation amount of the engine E can also be obtained in the same manner as the heat dissipation amount of the automatic transmission T described above.

  In the subsequent step S7, the rotation speed calculation means M4 has a first engine rotation speed at which the heat generation amount and heat dissipation amount of the engine E are equal, and a second engine rotation speed at which the heat generation amount and heat dissipation amount of the automatic transmission T are equal. Is calculated.

  Hereinafter, a case where the heat generation amount of the automatic transmission T is larger than the heat generation amount of the engine E, that is, a case where the control is performed based on the second engine rotation speed at which the heat generation amount and the heat dissipation amount of the automatic transmission T are equal will be described. The following description of FIGS. 5 and 6 is a case where the automatic transmission T is a belt-type continuously variable transmission.

  As shown in FIG. 5, when the engine speed increases, the heat generation amount of the automatic transmission T increases rapidly, whereas the heat release amount increases slowly, so that the heat generation amount becomes larger than the heat release amount. Conversely, when the engine speed decreases, the heat dissipation amount of the automatic transmission T rapidly decreases, whereas the heat generation amount decreases slowly, so that the heat generation amount becomes larger than the heat dissipation amount. Therefore, if the engine speed is kept within the range of Ne1 to Ne2, the amount of heat released becomes larger than the amount of heat generated, and the temperature of the automatic transmission T decreases. For example, when the engine rotation speed is in the state of Ne3, the temperature of the automatic transmission T rises because the heat generation amount is larger than the heat dissipation amount, but if the engine rotation speed is reduced from Ne3 to Ne2 to Ne1, The temperature of the automatic transmission T decreases.

  In subsequent step S8, the gear ratio determining means M5 uses the turbine rotation speed Nin (that is, engine rotation speed) determined in step S7 and the vehicle speed V detected by the vehicle speed sensor Sh in the shift map of FIG. 6D. Apply to determine the gear ratio of the automatic transmission T. Then, the transmission control means M6 controls the transmission ratio through the hydraulic control valve 22 to the transmission ratio determined by the transmission ratio determination means M5. This control is continued until the oil temperature Tm of the automatic transmission T, the oil temperature To of the engine E, and the coolant temperature Tw of the engine E all fall below the threshold value.

  FIG. 6D shows a shift map by the overheat suppression control of the power unit P of the present embodiment. The vertical axis is the turbine rotational speed Nin of the torque converter 14 and the horizontal axis is the vehicle speed V. AP = 0 in the figure indicates a state in which the accelerator pedal opening is zero (fully closed).

  The gear ratio determination means M5 determines that the vehicle is in an accelerated state if the accelerator pedal opening detected by the accelerator pedal opening sensor Si is equal to or greater than a threshold value, and the engine speed range in which the temperature of the automatic transmission T decreases. The transmission ratio of the automatic transmission T is set so that Ne1 to Ne2 is as high as possible. Further, if the accelerator pedal opening detected by the accelerator pedal opening sensor Si is less than the threshold value, it is determined that the vehicle is in a decelerating state, and the engine speed is made as high as possible at a rotational speed equal to or lower than the engine rotational speed in the acceleration state. The gear ratio of the automatic transmission T is set so that That is, the drive pulley diameter and the driven pulley diameter of the speed change mechanism 19 including the belt type continuously variable transmission mechanism are set.

  Thereby, when the accelerator pedal opening is equal to or greater than the threshold value, the driving force can be ensured to the maximum while suppressing the overheating of the power unit P. Also, when the accelerator pedal opening is less than the threshold value, the heat generation amount of the engine E is small, and when the fuel cut is performed, the heat generation amount is further reduced. High rotation speed can be set. However, with this control, the engine rotation speed decreases when the accelerator pedal is depressed for acceleration, and when the accelerator pedal is returned, the engine rotation speed increases, giving the driver a sense of incongruity. By setting the engine speed at the time of low accelerator pedal opening to be lower than the engine speed at the time of high accelerator pedal opening and as high as possible, the engine brake is effective while eliminating the above discomfort. Can be secured.

  Also, since the engine output torque changes according to the throttle opening during acceleration, the counterbalance engine rotation speed fluctuates due to the accelerator pedal operation, and there is a sense of incongruity. However, when the accelerator pedal is depressed in step S4 in FIG. As a result, it is possible to achieve a speed change characteristic without a sense of incongruity while suppressing a temperature rise.

  The case where the heat generation amount of the automatic transmission T is larger than the heat generation amount of the engine E has been described above. However, when the heat generation amount of the engine E is larger than the heat generation amount of the automatic transmission T, the heat generation of the engine E is generated. Control may be performed in the same manner as described above based on the first engine speed at which the amount and the heat radiation amount are equal. In this way, both overheating of the engine E and overheating of the automatic transmission T can be prevented.

  As shown in FIG. 6 (A), when the continuously variable transmission is set to the manual shift mode and the vehicle runs in a limit, there is a concern that the temperature of the power unit P rises due to the heavy use of the region where the engine speed is high. As shown in FIG. 6, there is a concern that the temperature of the power unit P rises when high load operation is continued in the S mode or L mode, and as shown in FIG. There is a concern that the driving force and the engine braking force are reduced only by reducing the ratio. Further, as shown in FIG. 7A, there is a concern that the temperature of the power unit P rises when the multistage automatic transmission is set to the S mode or the L mode and high load operation such as limit running or uphill running is continued. As shown in (B), when the vehicle is marginally driven in the manual transmission mode, there is a concern that the temperature of the power unit rises because a high engine speed region is frequently used. However, according to the present embodiment, the above-described problems can be solved by adopting the high-temperature automatic transmission mode shown in FIG. 6 (D) or FIG. 7 (C).

  FIG. 8 is a time chart showing an example of this control. When the temperature of the power unit P reaches the warning start temperature Tws at time t1, the driver is warned that the power unit P may be overheated. However, the driver ignores the warning and continues to operate in the WOT state. When the temperature of the power unit P reaches the control start temperature Tcs at time t2, the normal shift mode is switched to the high temperature shift mode, and the temperature of the power unit P is increased. Begins to decrease. As a result, when the temperature of the power unit P reaches the control release temperature Tcr at which hysteresis is set at time t3, the high-temperature shift mode is switched to the normal shift mode, and the temperature of the power unit P starts to rise.

  As described above, according to the present embodiment, it is possible to ensure the driving force of the power unit P and the advantage of the engine brake while reliably suppressing overheating of the power unit P. In addition, since overheating of the power unit P can be suppressed without requiring a large capacity radiator or oil cooler, an increase in cost, weight, and dimensions can be prevented.

  The embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

  For example, the drive source of the present invention is not limited to the engine E of the embodiment, and may be another drive source such as a motor / generator.

  The automatic transmission of the present invention is not limited to a belt-type continuously variable transmission, but is of any type of continuously variable transmission (CVT), multi-stage automatic transmission (AT), automatic manual transmission (AMT), dual clutch type. The present invention can also be applied to a transmission, a power transmission mechanism of a hybrid vehicle, and the like. Since a dual clutch transmission having an AMT or a dry clutch is generally not provided with an oil pump or an oil cooler, only the air heat radiation amount should be considered as the heat radiation amount.

  In addition, since the automatic transmission T of the embodiment is a belt-type continuously variable transmission, the transmission ratio calculation means M5 determines the engine speed according to whether the vehicle is in an acceleration state or a deceleration state. When the automatic transmission T is a stepped transmission, the gear ratio calculation means M5 determines the gear ratio based on the engine speed calculated by the rotation speed calculation means M4.

  In the embodiment, the temperature of the power unit P is detected using three parameters of the coolant temperature of the engine E, the oil temperature of the engine E, and the oil temperature of the automatic transmission T. If at least one of them is used, good.

E Engine (drive source)
T automatic transmission P power unit M2 heat generation amount calculation means M3 heat dissipation amount calculation means M4 rotational speed calculation means M5 gear ratio determination means M6 speed change control means

Claims (1)

The temperature of the power unit (P) comprising the drive source (E) and the automatic transmission (T) is detected. When the detected temperature is equal to or higher than a predetermined value, the speed ratio of the automatic transmission (T) is increased from the current speed ratio. In the protection control device of the power unit that prevents overheating by changing to the gear ratio on the side or low speed side,
A calorific value calculating means (M2) for calculating the calorific value of the power unit (P);
A heat dissipation amount calculating means (M3) for calculating a heat dissipation amount of the power unit (P);
A rotation speed calculation means (M4) for calculating the rotation speed of the drive source (E) in which the heat generation amount calculated by the heat generation amount calculation means (M2) is equal to the heat dissipation amount calculated by the heat dissipation amount calculation means (M3); ,
A gear ratio that can maintain the rotation speed calculated by the rotation speed calculation means (M4) when the vehicle is accelerated and a gear ratio that can maintain a rotation speed lower than the rotation speed when the vehicle is decelerated. A ratio determining means (M5);
A transmission control means (M6) for shifting the automatic transmission (T) to the transmission ratio determined by the transmission ratio determination means (M5) and maintaining the transmission ratio until the temperature falls below the predetermined value;
A power unit protection control device comprising:

Images