JP2015203451A - vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make recovery from torque-down easy, in a vehicle in which the torque-down control of an engine is performed at the occurrence of a stall of a torque converter.SOLUTION: In a vehicle in which a torque converter is arranged between an engine and an automatic transmission, when a start condition of protection control that an oil temperature in the torque converter exceeds a prescribed temperature α after it is determined that the torque converter is in a stall state, an ECU performs protection control for protecting the torque converter and its peripheral region from heat damage caused by a stall until a finish condition of the protection control that an oil temperature in the torque converter is lowered below a prescribed temperature β is established. In addition to engine torque-down control for reducing the torque of the engine, the ECU performs, as the protection control, T/C circulation pressure up-control which increases T/C circulation pressure for circulating oil between the inside and the outside of the torque converter.

Description

  The present invention relates to a vehicle in which a torque converter is provided between an engine and an automatic transmission.

  In the torque converter provided between the engine and the automatic transmission, the rotational speed difference between the input-side pump impeller and the output-side turbine liner is larger than a predetermined value (hereinafter referred to as “stall state”). Can occur. If the stalled state continues, the oil temperature in the torque converter increases, and the durability of the torque converter or its surrounding parts may be reduced.

  Japanese Patent Laid-Open No. 2008-38892 (Patent Document 1) discloses that when the torque converter is in a stalled state, engine torque down control is executed to reduce the engine torque in order to reduce the oil temperature in the torque converter. It is disclosed.

JP 2008-38892 A

  However, when the above-described engine torque down control is executed to reduce the oil temperature in the torque converter as in Patent Document 1, the engine torque is insufficient with respect to the torque requested by the user, and the vehicle running performance is temporarily reduced. May be reduced.

  A vehicle according to the present invention is a vehicle in which a torque converter is provided between an engine and an automatic transmission, and is capable of adjusting a circulating hydraulic pressure for circulating oil between the torque converter and the automatic transmission. Part and a control part which controls a pressure regulation part. When the oil temperature in the torque converter becomes higher than the oil temperature in the automatic transmission by a predetermined value or more, the control unit executes hydraulic pressure increase control for increasing the circulating oil pressure.

  According to such a configuration, when the oil temperature in the torque converter becomes higher than the oil temperature in the automatic transmission by a predetermined value or more, the low temperature oil in the automatic transmission is quickly transferred into the torque converter by the hydraulic pressure-up control. While flowing in, high temperature oil in the torque converter can be discharged to the outside of the torque converter at an early stage. Therefore, the oil temperature in the torque converter can be lowered early.

  Preferably, when the oil temperature in the torque converter becomes higher than the oil temperature in the automatic transmission by a predetermined value or more after the torque converter is in a stalled state, the control unit determines the oil temperature in the torque converter and the automatic transmission in the automatic transmission. The hydraulic pressure increase control is executed until the difference from the oil temperature becomes less than a predetermined value, and the torque reduction control for decreasing the engine torque is executed.

  According to such a configuration, since the torque down control is executed in addition to the oil pressure up control, the oil temperature in the torque converter can be lowered earlier.

1 is an overall configuration diagram of a vehicle. It is a figure which shows typically the structure of the hydraulic circuit for circulating oil between the inside and the exterior of a torque converter. It is a flowchart which shows the flow of a process of ECU. It is a figure which shows the change of T / C exit oil temperature THOCL and A / T internal oil temperature THO by protection control.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is an overall configuration diagram of a vehicle 1 according to the present embodiment. Vehicle 1 includes an engine 10, a torque converter 20, an automatic transmission 30, drive wheels 40, and an ECU (Electronic Control Unit) 100.

  The engine 10 is an internal combustion engine such as a gasoline engine or a diesel engine. The engine 10 is connected to the automatic transmission 30 via the torque converter 20. The output shaft of the automatic transmission 30 is connected to the drive wheels 40.

  Torque converter 20 includes a pump impeller coupled to the crankshaft of engine 10, a turbine liner coupled to the input shaft of automatic transmission 30, and a stator provided between the pump impeller and the turbine liner. Oil circulates inside the torque converter 20 (see FIG. 2 described later). When the crankshaft of the engine 10 rotates, the pump impeller rotates to produce an oil flow, and the turbine runner rotates due to the inertial force of the oil flow from the pump impeller. The stator rectifies the oil from the turbine runner and returns it to the pump impeller to generate a torque amplification action.

  The automatic transmission 30 is a hydraulic automatic transmission that can change a gear ratio (ratio of an input shaft to an output shaft of the automatic transmission 30). The automatic transmission 30 in the present embodiment is a stepped automatic transmission and includes a plurality of friction engagement elements (clutch and brake) that are operated by hydraulic pressure. The gear ratio of the automatic transmission 30 is changed by changing the combination for engaging or releasing these friction engagement elements. The automatic transmission 30 may be a continuously variable automatic transmission.

  The vehicle 1 includes rotational speed sensors 2 and 3 and oil temperature sensors 4 and 5. The rotational speed sensor 2 detects the crankshaft rotational speed of the engine 10 (hereinafter referred to as “engine rotational speed NE”). The rotational speed sensor 3 detects the rotational speed of the turbine liner of the torque converter 20 (hereinafter referred to as “turbine rotational speed NT”).

  Oil temperature sensor 4 detects the temperature of oil discharged from the inside of torque converter 20 to the outside (hereinafter referred to as “T / C outlet oil temperature THOCL”) as the oil temperature inside torque converter 20. Oil temperature sensor 5 detects the temperature of the oil inside automatic transmission 30 (hereinafter referred to as “A / T internal oil temperature THO”) as the oil temperature outside torque converter 20.

  In addition to the rotational speed sensors 2 and 3 and the oil temperature sensors 4 and 5, the vehicle 1 detects various physical quantities necessary for controlling the vehicle 1 such as an accelerator pedal depression amount and a vehicle speed by the user. A plurality of other sensors (not shown) are provided. These sensors transmit a detection result to ECU100.

  The ECU 100 includes a CPU (Central Processing Unit) and a memory (not shown). ECU 100 executes a predetermined calculation process based on information from each sensor and information stored in the memory, and controls each device of vehicle 1 based on the calculation result.

  FIG. 2 is a diagram schematically showing a configuration of a hydraulic circuit 50 for circulating oil between the inside and the outside of the torque converter 20.

  The hydraulic circuit 50 includes an oil pan 51, an oil cooler 56, and a pressure adjusting unit 57. The pressure adjustment unit 57 includes an oil pump 52, a primary regulator valve 53, a linear solenoid valve (hereinafter also referred to as “SLT”) 54, and a secondary regulator valve 55.

  The oil pump 52 operates using the engine 10 as a power source, and sucks and discharges oil stored in the oil pan 51. The oil temperature sensor 5 described above detects the temperature of the oil discharged from the oil pump 52 as the A / T internal oil temperature THO.

  The discharge hydraulic pressure of the oil pump 52 is supplied to the primary regulator valve 53. Note that the discharge hydraulic pressure of the oil pump 52 is also supplied to the SLT 54.

  The SLT 54 adjusts the discharge hydraulic pressure of the oil pump 52 based on a control signal from the ECU 100, and outputs the adjusted hydraulic pressure (hereinafter also referred to as “SLT pressure”) to the primary regulator valve 53.

  The primary regulator valve 53 operates using the SLT pressure from the SLT 54 as a pilot pressure, and regulates the discharge hydraulic pressure of the oil pump 52 to a value corresponding to the SLT pressure. The hydraulic pressure regulated by the primary regulator valve 53 is used as a source pressure (hereinafter referred to as “line pressure”) for operating the automatic transmission 30. The line pressure is also output to the secondary regulator valve 55.

  The secondary regulator valve 55 generates hydraulic pressure (hereinafter referred to as “T / C circulation pressure”) for circulating oil between the torque converter 20 and the automatic transmission 30 using the line pressure as the original pressure, and the torque converter 20. Output to. The secondary regulator valve 55 is configured to adjust the T / C circulation pressure to a higher value as the line pressure is higher.

  The oil that has flowed into the torque converter 20 from the secondary regulator valve 55 circulates inside the torque converter 20 and absorbs heat inside the torque converter 20, and then is discharged to the outside of the torque converter 20 to be an oil cooler. 56. The oil temperature sensor 4 described above detects the temperature of the oil near the oil outlet of the torque converter 20 as the T / C outlet oil temperature THOCL. The oil cooled by the oil cooler 56 is returned to the oil pan 51.

  In the vehicle 1 having the above-described configuration, a “stall state” in which the rotational speed difference (slip) between the pump impeller of the torque converter 20 and the turbine liner is larger than a predetermined value may occur. Here, the “predetermined value” is a value at which the heat generation amount per unit time of the torque converter 20 exceeds the heat release amount per unit time. That is, in the stall state, a part of the heat generated inside the torque converter 20 is accumulated without being released to the outside.

  Therefore, when the stall state continues, the oil temperature inside the torque converter 20 rises, and the durability of the torque converter 20 or its peripheral portion (for example, a metal bush disposed between the torque converter 20 and the automatic transmission 30) is increased. May deteriorate. In order to prevent this, it is desirable to perform control (hereinafter also referred to as “protection control”) that protects the torque converter 20 and its surrounding parts from thermal damage due to stall.

  Conventionally, as the protection control, there is known a control that executes a control (hereinafter referred to as “engine torque down control”) for reducing the torque of the engine 10 by a predetermined amount from the torque requested by the user (torque that should be output). By reducing the torque of the engine 10, slippage of the torque converter 20 is reduced and the amount of heat generated by the torque converter 20 is lower than the amount of heat released, so that the torque converter 20 is cooled.

  However, when the engine torque reduction control is performed, the torque of the engine 10 is insufficient with respect to the torque requested by the user, so that the running performance of the vehicle may be temporarily reduced. Therefore, when the engine torque down control is executed due to the torque converter 20 being in the stalled state, it is desired to return from the engine torque down control at an early stage.

  Therefore, ECU 100 according to the present embodiment performs control for increasing the T / C circulation pressure by a predetermined pressure (hereinafter also referred to as “T / C circulation pressure up control”) in addition to engine torque reduction control as protection control.

  FIG. 3 is a flowchart showing a flow of protection control processing performed by the ECU 100. This flowchart is repeatedly executed at a predetermined cycle.

  In step (hereinafter, “step” is abbreviated as “S”) 10, ECU 100 monitors the heat generation amount per unit time (hereinafter referred to as “T / C instantaneous heat generation amount qdot”) inside torque converter 20. The ECU 100 constantly calculates the T / C instantaneous heat generation amount qdot using the rotational speed difference between the pump impeller of the torque converter 20 and the turbine liner and the capacity coefficient of the torque converter 20 as parameters. In the process of S10, the T / C instantaneous calorific value qdot is monitored.

  In S20, ECU 100 determines whether or not torque converter 20 is in a stalled state based on T / C instantaneous heat generation amount qdot. ECU 100 determines that torque converter 20 is in a stalled state when T / C instantaneous heat generation amount qdot exceeds a predetermined amount. Thus, in the present embodiment, it is possible to determine the presence or absence of a stall state based on the T / C instantaneous heat generation amount qdot. The “predetermined amount” is, for example, per unit time of the torque converter 20 when engine torque that can be started with a gross vehicle weight GVW (GROSS VEHICLE WEIGHT) on an uphill road having a predetermined angle of inclination is input to the torque converter 20. The calorific value of can be set.

  If torque converter 20 is not in the stalled state (NO in S20), ECU 100 ends the process.

  On the other hand, when torque converter 20 is in a stalled state (YES in S20), ECU 100 determines in S30 whether a start condition for protection control is satisfied. In the present embodiment, the protection control start condition is set to a condition that the T / C outlet oil temperature THOCL (the oil temperature inside the torque converter 20) exceeds a predetermined temperature α. Here, predetermined temperature α is set in advance to a value (for example, 150 ° C.) that is less than the allowable temperature of torque converter 20 and its peripheral components. If the protection control start condition is not satisfied (NO in S30), ECU 100 ends the process.

  If the protection control start condition is satisfied (YES in S30), ECU 100 starts protection control in S40. As described above, ECU 100 according to the present embodiment executes T / C circulation pressure up control as protection control in addition to engine torque down control.

  The torque down control is control for reducing the torque of the engine 10 by a predetermined amount from the torque requested by the user.

  The T / C circulation pressure up control is a control for increasing the T / C circulation pressure by a predetermined pressure. The ECU 100 increases the line pressure, which is the original pressure of the T / C circulation pressure, so that the T / C circulation pressure increases by a predetermined pressure. Note that, as described above, the ECU 100 increases the line pressure by controlling the SLT 54 to increase the SLT pressure.

  During the execution of the protection control, the ECU 100 determines in S50 whether or not an end condition for the protection control is satisfied. In the present embodiment, the end condition of the protection control is set to a condition that the T / C outlet oil temperature THOCL has decreased below the predetermined temperature β. Here, the predetermined temperature β is set to a value (for example, 130 ° C.) that is lower by a predetermined temperature than the predetermined temperature α (for example, 150 ° C.) used for the start condition of protection control in order to provide hysteresis. The predetermined temperature β may be the same value as the predetermined temperature α.

  If the protection control end condition is not satisfied (NO in S50), ECU 100 returns the process to S40, and continues the protection control.

  If the protection control end condition is satisfied (YES in S50), ECU 100 ends the protection control in S60.

  FIG. 4 is a diagram showing changes in the T / C outlet oil temperature THOCL and the A / T internal oil temperature THO by the protection control.

  When it is determined that the torque converter 20 is in the stalled state, it is determined whether or not a start condition for protection control (a condition that the T / C outlet oil temperature THOCL exceeds the predetermined temperature α) is satisfied.

  When the start condition of the protection control is satisfied at time t1, the protection control is started. In the present embodiment, T / C circulation pressure up control is executed as protection control in addition to engine torque down control.

  By this T / C circulation pressure up control, low-temperature oil outside the torque converter 20 (oil that has not absorbed heat generated by the stall) is allowed to flow into the torque converter 20 at an early stage, and the torque converter 20 High-temperature oil (oil that has absorbed heat generated by the stall) can be discharged to the outside of the torque converter 20 at an early stage. Therefore, the T / C outlet oil temperature THOCL can be reduced earlier than in the case where only engine torque down control is performed as protection control (see the alternate long and short dash line). That is, it is possible to easily satisfy the protection control end condition.

  Then, when the end condition of protection control (condition that the T / C outlet oil temperature THOCL has decreased below the predetermined temperature β) is satisfied at time t2, the protection control is ended. Thereby, it is possible to quickly return from the engine torque down control.

  As described above, ECU 100 according to the present embodiment performs T / C circulation pressure up control in addition to engine torque down control as protection control. Thereby, the fall of T / C exit oil temperature THOCL can be accelerated | stimulated, and it can reset from engine torque down control at an early stage.

<Modification>
The above-described embodiment can be modified as follows, for example.

  (1) In the embodiment described above, the protection control start condition is the condition that the T / C outlet oil temperature THOCL exceeds the predetermined temperature α, but the protection control start condition is not limited to this.

  For example, the oil temperature inside the torque converter 20 is lowered by the T / C circulation pressure up control because the oil temperature inside the torque converter 20 is higher than the oil temperature inside the automatic transmission 30. The condition that the T / C outlet oil temperature THOCL is higher than the A / T internal oil temperature THO by a predetermined value or more may be set as the protection control start condition.

  Further, even if the integrated value of the T / C instantaneous heat generation amount qdot is calculated as “T / C heat generation amount Qs” and the condition that the T / C heat generation amount Qs exceeds a predetermined amount is added to the protection control start condition. Good.

  Further, from the viewpoint of more appropriately suppressing thermal damage due to stall, at least one of a condition that the T / C outlet oil temperature THOCL exceeds a predetermined temperature and a condition that the T / C heat generation amount Qs exceeds a predetermined amount The establishment of the protection control may be a start condition for protection control.

  (2) In the above-described embodiment, the end condition for protection control is the condition that the T / C outlet oil temperature THOCL has decreased below the predetermined temperature β, but the end condition for protection control is not limited to this.

  For example, a condition that the temperature difference between the T / C outlet oil temperature THOCL and the A / T internal oil temperature THO is less than a predetermined value may be added to the protection control end condition. That is, by the T / C circulation pressure up control, the T / C outlet oil temperature THOCL decreases and approaches the A / T internal oil temperature THO (see FIG. 4). Focusing on this point, a condition that the temperature difference between the T / C outlet oil temperature THOCL and the A / T internal oil temperature THO is less than a predetermined value may be added to the protection control end condition.

  A condition that the T / C heat generation amount Qs is smaller than the heat dissipation amount of the torque converter 20 may be added to the protection control end condition. Here, the heat dissipation amount is obtained by, for example, preliminarily obtaining and storing the heat dissipation amount per unit time of the torque converter 20 in a predetermined operation state (for example, an idle state), and storing the heat dissipation amount per unit time. It can be set to a value obtained by multiplying the execution time of the protection control.

  Further, from the viewpoint of returning from the engine torque down control earlier, the condition that the T / C outlet oil temperature THOCL has decreased below the predetermined temperature β, the T / C outlet oil temperature THOCL, the A / T internal oil temperature THO, The end condition of the protection control is that at least one of the condition that the temperature difference between the two is less than the predetermined value and the condition that the T / C heat generation amount Qs is smaller than the heat dissipation amount of the torque converter 20 is satisfied. It is good.

  (3) In the embodiment described above, both engine torque down control and T / C circulation pressure up control are executed as protection control. However, only T / C circulation pressure up control may be executed as protection control. Good.

  Further, in the above-described embodiment, the protection control is executed when the torque converter 20 is in the stalled state and the start condition of the protection control is satisfied, but whether or not the torque converter 20 is in the stalled state is determined. Regardless, the protection control may be executed when the protection control start condition is satisfied.

  Therefore, for example, when the T / C outlet oil temperature THOCL becomes higher than the A / T internal oil temperature THO by a predetermined value or more regardless of whether the torque converter 20 is in a stalled state, the T / C outlet oil temperature is The T / C circulation pressure up control may be executed without executing the engine torque down control until the temperature difference between THOCL and the A / T internal oil temperature THO becomes less than a predetermined value.

The above-described embodiment and its modifications can be combined as appropriate.
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1 vehicle, 2, 3 rotational speed sensor, 4, 5 sensor, 10 engine, 20 torque converter, 30 automatic transmission, 40 drive wheel, 50 hydraulic circuit, 51 oil pan, 52 oil pump, 53 primary regulator valve, 54 SLT , 55 Secondary regulator valve, 56 Oil cooler, 57 Pressure regulator.

Claims (2)

A vehicle in which a torque converter is provided between the engine and the automatic transmission,
A pressure adjusting unit capable of adjusting a circulating hydraulic pressure for circulating oil between the torque converter and the automatic transmission;
A control unit for controlling the pressure regulating unit,
The control unit executes a hydraulic pressure-up control for increasing the circulating hydraulic pressure when an oil temperature in the torque converter becomes higher than a predetermined value by a temperature higher than an oil temperature in the automatic transmission.   When the oil temperature in the torque converter becomes higher than the predetermined value by the oil temperature in the automatic transmission after the torque converter is in a stalled state, the control unit 2. The vehicle according to claim 1, wherein the hydraulic pressure increase control is executed and torque down control for decreasing the torque of the engine is executed until a difference from an oil temperature in the automatic transmission becomes less than the predetermined value.

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