JP3968005B2 - Shift control device for automatic transmission - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a shift control device used in an automatic transmission.
[0002]
[Prior art]
[Patent Document 1]
JP-A-9-217824
Conventionally, in order to prevent an increase in the oil temperature in the automatic transmission, there is a method of limiting the input rotation speed to the automatic transmission when the oil temperature becomes high. An example of such a shift control device for an automatic transmission is disclosed in Japanese Patent Laid-Open No. 9-217824.
[0003]
[Problems to be solved by the invention]
In such a conventional shift control device for an automatic transmission, the speed of the engine is decreased to prevent the oil temperature from rising by controlling the gear ratio. However, in such control, since the gear ratio is changed, the driver feels uncomfortable because an unintended gear shift occurs even though the driver is not operating anything.
Accordingly, an object of the present invention is to prevent an increase in oil temperature while preventing such a sense of incongruity from being felt.
[0004]
Further, in such a conventional shift control device for an automatic transmission, the oil temperature is lowered by reducing the power performance of the vehicle by limiting the input rotational speed to the automatic transmission. However, the hydraulic pressure command for the automatic transmission is the same as the normal hydraulic pressure command that does not limit the input rotational speed, and the effect of lowering the oil temperature due to heat generated from the oil pump or the like was low. In particular, when the automatic transmission is applied to a vehicle equipped with a high-power engine, there is a problem that the oil temperature cannot be sufficiently lowered by limiting the input rotation to the automatic transmission.
[0005]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a shift control device for an automatic transmission that effectively prevents an increase in oil temperature in view of the above-described conventional problems.
[0006]
[Means for Solving the Problems]
The present invention relates to an automatic transmission that is connected to an engine and performs transmission by applying hydraulic pressure to a transmission mechanism unit, and an oil temperature sensor that detects an oil temperature of the transmission mechanism unit and an engine that limits the output torque of the engine. A torque limiting means and a vehicle speed sensor mounted on the vehicle for detecting the vehicle speed of the vehicle are provided. The engine torque limiting means is detected by the oil temperature sensor when the vehicle speed detected by the vehicle speed sensor is equal to or higher than a predetermined speed. When the oil temperature falls within a predetermined temperature range, the engine output torque is limited. When the vehicle speed is lower than the predetermined speed, the output torque limit is not executed .
[0007]
【The invention's effect】
According to the present invention, when the oil temperature detected by the oil temperature sensor falls within a predetermined temperature range, the engine torque limiting means limits the output torque of the engine and decreases the output torque. As a result, the speed of the vehicle is reduced and the friction is reduced accordingly, so that the oil temperature of the transmission mechanism can be lowered. On the other hand, when the vehicle speed is lower than the predetermined speed, the output torque limit is not executed, so that the start performance of the vehicle is not deteriorated.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described by way of examples.
FIG. 1 shows a schematic configuration in which the present invention is applied to a belt type continuously variable transmission using a V belt, and FIG. 2 shows a schematic configuration of a hydraulic control unit and a CVT control unit.
In FIG. 1, a belt type continuously variable transmission 3 including a transmission mechanism unit 5 having a forward / reverse switching mechanism 4 and a torque converter 2 having a lock-up clutch is connected to an engine 1. The transmission mechanism unit 5 includes a primary pulley 10 on the input shaft side as a pair of variable pulleys and a secondary pulley 11 connected to the output shaft 13. The pair of variable pulleys 10 and 11 are connected by a V belt 12. The output shaft 13 is connected to the differential 6 via an idler gear 14.
[0009]
The transmission ratio of the transmission mechanism unit 5 and the contact friction force of the V belt 12 are controlled by a hydraulic control unit 100 that operates according to a command from the CVT control unit 20. The CVT control unit 20 is connected to an engine control unit (ECU) 21 that controls the engine 1 and exchanges information with each other. An engine speed sensor 15 that detects the speed of the engine 1 is connected to the engine control unit 21.
[0010]
The CVT control unit 20 receives input torque information such as a target torque and an actual torque when controlling the torque of the engine 1 from the engine control unit 21. The CVT control unit 20 determines the gear ratio and the contact friction force from the input torque information, the throttle opening (TVO) from the throttle opening sensor 24, and the like.
[0011]
The primary pulley 10 of the transmission mechanism unit 5 is disposed at a position opposed to the fixed conical plate 10b that rotates integrally with the input shaft and the fixed conical plate 10b to form a V-shaped pulley groove. The movable conical plate 10a can be displaced in the axial direction according to the hydraulic pressure (hereinafter referred to as primary pressure) acting on the cylinder chamber 10c.
[0012]
The secondary pulley 11 is disposed at a position opposed to the fixed conical plate 11b that rotates integrally with the output shaft 13 and the fixed conical plate 11b to form a V-shaped pulley groove, and to the secondary pulley cylinder chamber 11c. It is composed of a movable conical plate 11a that can be displaced in the axial direction in accordance with the acting hydraulic pressure (hereinafter referred to as secondary pressure).
The primary pulley cylinder chamber 10c and the secondary pulley cylinder chamber 11c are set to an equal pressure receiving area.
[0013]
Input torque input from the engine 1 is input to the transmission mechanism 5 via the torque converter 2 and transmitted from the primary pulley 10 to the secondary pulley 11 via the V belt 12. By moving the movable conical plate 10a of the primary pulley 10 and the movable conical plate 11a of the secondary pulley 11 in the axial direction and changing the contact radius between the V belt 12 and the pulleys 10 and 11, the primary pulley 10 and the secondary pulley 11 can be continuously changed.
[0014]
As shown in FIG. 2, the hydraulic control unit 100 includes a pressure regulating valve 60 that controls line pressure, a transmission control valve 30 that controls primary (Pri) pressure to the primary pulley cylinder chamber 10c, and a secondary pulley cylinder chamber 11c. The pressure reducing valve 61 that controls the secondary (Sec) pressure is mainly configured.
The speed change control valve 30 is connected to a servo link 50 constituting a mechanical feedback mechanism, is driven by a step motor 40 connected to one end of the servo link 50, and is movable of the primary pulley 10 connected to the other end of the servo link 50. The groove width, that is, feedback of the actual gear ratio is received from the conical plate 10a.
[0015]
The line pressure control system includes a pressure regulating valve 60 including a solenoid 59 that regulates the hydraulic pressure generated by the hydraulic pump 80, and is predetermined according to an operation state according to a command (for example, a duty signal) from the CVT control unit 20. Regulate to the line pressure. The line pressure is supplied to a speed change control valve 30 that controls the primary pressure and a pressure reducing valve 61 that includes a solenoid 62 that controls the secondary pressure.
[0016]
The gear ratio between the primary pulley 10 and the secondary pulley 11 is controlled by a step motor 40 driven in accordance with a shift command signal from the CVT control unit 20, and shift control is performed in accordance with the displacement of a servo link 50 that responds to the step motor 40. The spool 31 of the valve 30 is driven, the primary pressure obtained by adjusting the line pressure supplied to the speed change control valve 30 is supplied to the primary pulley 10, and the groove width is variably controlled to be set to a predetermined speed ratio.
[0017]
The shift control valve 30 supplies and discharges hydraulic pressure to and from the primary pulley cylinder chamber 10c by displacement of the spool 31, and adjusts the primary pressure so that the target gear ratio commanded at the drive position of the step motor 40 is obtained. When the shifting is actually completed, the spool 31 is closed in response to the displacement from the servo link 50.
[0018]
Here, the CVT control unit 20 in FIG. 1 includes a primary pulley speed sensor 26 that detects the rotational speed of the primary pulley 10 of the transmission mechanism unit 5 and a secondary pulley speed sensor 27 that detects the rotational speed (or vehicle speed) of the secondary pulley 11. The signal from the secondary pressure sensor 28 that detects the secondary pressure acting on the secondary pulley cylinder chamber 11c of the secondary pulley, the range signal from the inhibitor switch 23, and the opening degree of the throttle that is opened and closed by the driver's operation are detected. The throttle opening (TVO) from the throttle opening sensor 24 and the oil temperature applied to the transmission mechanism 5 detected by the oil temperature sensor 25 are read to variably control the gear ratio and the contact friction force of the V-belt 12. To do.
[0019]
As shown in FIG. 2, the CVT control unit 20 determines a target gear ratio according to the vehicle speed and the throttle opening, and drives the step motor 40 to control the actual gear ratio toward the target gear ratio. And a pulley pressure control unit 202 that calculates the thrust (contact friction force) of the primary pulley 10 and the secondary pulley 11 according to the input torque, gear ratio, oil temperature, and the like, and converts the calculated thrust into hydraulic pressure. .
[0020]
The pulley pressure control unit 202 determines the target value of the line pressure from the input torque information, the gear ratio based on the primary pulley rotation speed and the secondary pulley rotation speed, and the oil temperature, and drives the solenoid 59 of the pressure regulating valve 60 to drive the line. The pressure is controlled, the target value of the secondary pressure is determined, the solenoid 62 of the pressure reducing valve 61 is driven according to the detected value and the target value of the secondary pressure sensor 28, and the secondary pressure is controlled by feedback control (closed loop control). To do.
[0021]
Next, the flow of processing performed by the pulley pressure control unit to prevent an increase in the oil temperature applied to the transmission mechanism unit will be described using the flowchart of FIG.
In step 100, the pulley pressure control unit 202 monitors the oil temperature detected by the oil temperature sensor 25, and in step 101 monitors the vehicle speed obtained from the rotational speed detected by the secondary pulley speed sensor 27.
[0022]
In step 102, it is determined whether the monitored oil temperature and vehicle speed satisfy predetermined setting conditions. If the oil temperature and vehicle speed satisfy the setting conditions, the process proceeds to step 103, where the setting conditions are satisfied. If not, return to step 100 and continue monitoring the oil temperature and vehicle speed.
In the present embodiment, the predetermined setting condition in step 102 is that the oil temperature is equal to or higher than a predetermined temperature (for example, 120 ° C.) and the vehicle speed is equal to or higher than the predetermined speed (for example, 50 km / h).
[0023]
In step 103, the pulley pressure control unit 202 instructs the engine control unit 21 to reduce the engine torque according to the oil temperature detected by the oil temperature sensor 25, and the output torque of the engine is transmitted through the engine control unit 21. Make restrictions. As shown in FIG. 4, the engine output torque is limited by gradually decreasing the engine output torque as the oil temperature rises, and a sudden engine output torque fluctuation causes a shock to the vehicle. The output torque is limited so that there is no.
[0024]
When the output torque of the engine is limited, the input torque input to the belt type continuously variable transmission 3 is reduced. Therefore, in step 104, the pulley pressure control unit 202 adjusts the hydraulic pressure applied to the transmission mechanism unit 5 to a hydraulic pressure corresponding to the input torque.
Here, the pulley pressure control unit 202 actually applies the torque limit value instructed to the engine control unit 21 to limit the engine output torque in step 103 and the torque actually output from the engine, that is, the torque converter. The input actual torque is compared, the torque limit value or the torque value with the larger actual torque is set as the input torque, and the line pressure is adjusted according to this input torque. As a result, it is possible to adjust the hydraulic pressure according to the output torque of the engine after the limit without causing the V belt 12 to slip.
When the above process is completed, the process returns to step 100 and the above process is repeated.
[0025]
In this embodiment, the secondary pulley speed sensor 27 constitutes a vehicle speed sensor in the present invention. In this embodiment, step 103 constitutes engine torque limiting means in the present invention, and step 104 constitutes hydraulic control means in the present invention.
[0026]
The present embodiment is configured as described above, and limits the engine output torque when the hydraulic pressure applied to the transmission mechanism unit 5 is equal to or higher than a predetermined temperature and the vehicle speed is equal to or higher than the predetermined speed. The torque is reduced, and the hydraulic pressure applied to the transmission mechanism unit 5 is adjusted according to the input torque input to the belt type continuously variable transmission 3. As a result, the speed of the vehicle is reduced, and accordingly, friction or the like is reduced, the amount of minute slip of the belt is reduced, and a decrease in the oil temperature can be promoted. Further, by lowering the hydraulic pressure in accordance with the input torque, it is possible to reduce the friction of the oil pump that generates the hydraulic pressure, and it is possible to reduce the contact friction force when the V belt 12 is sandwiched by the pulley, so that the oil temperature is further increased. Can be reduced.
[0027]
When limiting the output torque of the engine, the output torque is limited for each oil temperature detected by the oil temperature sensor 25, and further the torque limit value is variable so as to take a continuous value with respect to the change in the oil temperature. By doing so, a shock is not generated in the vehicle due to a sudden change in the output torque of the engine, and a smooth torque change can be obtained.
[0028]
Also, when limiting the engine output torque, the engine output torque is reduced as the oil temperature increases, so at high oil temperatures when it is difficult for the oil pump that generates oil pressure to generate high oil pressure. Also, it is possible to generate a hydraulic pressure corresponding to the output torque of the engine and supply it to the transmission mechanism unit 5.
When adjusting the hydraulic pressure according to the output torque of the engine to which the restriction has been applied, the torque limit value instructed to the engine control unit 21 and the torque converter are actually input to limit the output torque of the engine. The larger torque value is set as the input torque and the hydraulic pressure applied to the transmission mechanism unit 5 is adjusted. As a result, the hydraulic pressure setting corresponding to the input torque can be maintained, and the oil temperature can be lowered while maintaining the belt capacity.
[0029]
That is, as shown in FIG. 5, when the torque limit value is larger than the actual torque (the actual torque increases with time and approaches the torque limit value), the actual torque is set as the input torque. When adjusting the hydraulic pressure, there is a time lag from the detection of the actual torque to the adjustment of the hydraulic pressure, so the actual torque further increases during the pressure adjustment. Therefore, a hydraulic pressure lower than the hydraulic pressure for generating the necessary belt capacity is generated. As a result, belt slip occurs.
Therefore, in this case, such a problem does not occur if the torque limit value is set as the input torque.
[0030]
On the other hand, when the actual torque is greater than the torque limit value as shown in FIG. 6 (at this time, the actual torque decreases with time and approaches the torque limit value), the torque limit value is set as the input torque. When the hydraulic pressure is adjusted, the actual torque remains higher than the torque limit value even at the time of the pressure adjustment, so that a hydraulic pressure lower than the hydraulic pressure for generating the necessary belt capacity is generated. As a result, belt slip occurs.
Therefore, in this case, if the actual torque is set as the input torque, even if a time lag occurs from the detection of the actual torque to the adjustment of the hydraulic pressure, the actual torque decreases as time passes. The hydraulic pressure for generating the belt capacity can be secured.
[0031]
Since the output torque of the engine is not limited when the vehicle speed is low (for example, less than 50 km / h), the start performance of the vehicle can be prevented from deteriorating.
In this embodiment, the predetermined setting conditions for the oil temperature and the vehicle speed are the cases where the oil temperature is equal to or higher than the predetermined temperature and the vehicle speed is equal to or higher than the predetermined speed. However, the present invention is not limited to this, and the predetermined conditions are set as appropriate. be able to.
Furthermore, although the example which applied this invention to the belt-type continuously variable transmission using a V belt was shown, it is not limited to this, You may apply to the other automatic transmission which performs a hydraulic pressure action.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment in the present invention.
FIG. 2 is a diagram showing a schematic configuration of a hydraulic control unit and a CVT control unit.
FIG. 3 is a diagram showing a flow of processing for limiting engine output torque.
FIG. 4 is a graph showing the relationship between engine output torque and oil temperature.
FIG. 5 is a diagram showing a case where the actual torque increases with time.
FIG. 6 is a diagram illustrating a case where actual torque decreases with time.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Engine 3 Belt type continuously variable transmission 4 Forward / reverse switching mechanism 5 Transmission mechanism unit 10 Primary pulley 11 Secondary pulley 20 CVT control unit 21 Engine control unit 25 Oil temperature sensor 27 Secondary pulley speed sensor 80 Hydraulic pump 100 Hydraulic control unit 201 Control unit 202 Pulley pressure control unit

Claims (6)

In an automatic transmission that is connected to an engine and performs a shift by applying hydraulic pressure to a transmission mechanism unit,
An oil temperature sensor for detecting the oil temperature of the transmission mechanism,
Engine torque limiting means for limiting the output torque of the engine ;
A vehicle speed sensor mounted on the vehicle for detecting the vehicle speed of the vehicle ;
The engine torque limiting means adjusts the output torque of the engine when the vehicle temperature detected by the vehicle speed sensor is equal to or higher than a predetermined speed and the oil temperature detected by the oil temperature sensor falls within a predetermined temperature range. A shift control apparatus for an automatic transmission , wherein a restriction is applied and the output torque restriction is not executed if the vehicle speed is less than the predetermined speed . When the engine torque limiting means limits the output torque of the engine, the torque limit value of the engine output torque is made variable according to the oil temperature detected by the oil temperature sensor. The shift control apparatus for an automatic transmission according to claim 1. When the engine torque limiting means makes the torque limit value of the output torque variable according to the oil temperature detected by the oil temperature sensor, the oil temperature detected by the oil temperature sensor becomes higher. The shift control apparatus for an automatic transmission according to claim 2, wherein the output torque of the engine is limited so that the output torque of the engine becomes small . When the engine torque limiting means varies the torque limit value of the output torque of the engine according to the oil temperature detected by the oil temperature sensor, it takes a continuous value with respect to the change in the oil temperature. 4. The shift control device for an automatic transmission according to claim 2, wherein the torque limit value is variable . Hydraulic control means for controlling the hydraulic pressure applied to the speed change mechanism,
When the output torque of the engine is limited by the engine torque limiting means, the hydraulic pressure control means controls the hydraulic pressure applied to the transmission mechanism unit according to the torque limit value of the output torque. The shift control device for an automatic transmission according to any one of claims 1 to 4 . The hydraulic control means compares the torque limit value instructed by the engine torque limiting means with the actual torque actually output from the engine, and acts on the speed change mechanism unit according to the larger torque value. The shift control device for an automatic transmission according to any one of claims 1 to 5, wherein the hydraulic pressure is controlled .

Images