JP5816607B2 - Automatic transmission and its high oil temperature control method - Google Patents

Description

  The present invention relates to high oil temperature control that is performed when the oil temperature of an automatic transmission becomes high.

  In automatic transmissions, oil is used for the operation of control valves, the engagement and release of frictional engagement elements, the lubrication and cooling of components. When the oil temperature rises and the viscosity of the oil decreases, these functions are deteriorated, so it is important to manage the oil temperature appropriately.

  For this reason, generally, based on the detected value of the oil temperature or the duration of the high load state, etc., it is judged whether the oil temperature has risen above the allowable upper limit temperature, and has risen above the allowable upper limit temperature. When it is judged, the engine torque limit, the rotation speed limit, etc. are performed to suppress the rise in oil temperature, or the flow rate to the oil cooler is increased to promote oil cooling. (Patent Document 1).

JP 7-317578 A

  The oil temperature rises due to contact between the power train member such as a torque converter, a drum, or a clutch and the oil, or shearing. One of the causes for the oil temperature to rise above the allowable upper limit temperature is a decrease in the discharge amount of the oil pump that occurs during continuous high-speed running.

  This is because the amount of air contained in the oil increases and the efficiency of the oil pump decreases when the oil is agitated when the rotating body such as a gear comes into contact with the oil during continuous high-speed running or the like. It has been found that when the efficiency of the oil pump decreases, the oil pump discharge rate, and consequently the flow rate to the oil cooler, decreases, and the oil temperature rises above the allowable upper limit temperature. In addition, it is understood that the amount of air contained in the oil differs between the new oil with a short mileage and the old oil with a long mileage due to the viscosity due to the oil temperature and aging of the antifoam added to the oil. It was.

  According to the prior art, the oil temperature is monitored directly or indirectly, and when it is determined that the oil temperature has risen above the allowable upper limit temperature, torque limitation or the like of the engine is started. However, according to the prior art, the viscosity according to the oil temperature between the new oil and the old oil, and the aged deterioration of the antifoaming agent added to the oil are not considered. Setting the allowable oil temperature without considering these physical property changes in the new and old oils as in the prior art means that if the new oil is still capable of fully exhibiting its viscosity and defoaming effect, the timing of the deviation before the limit allowable temperature On the other hand, if the old oil is not capable of sufficiently exhibiting the viscosity and defoaming effect, the oil pump performance may be deteriorated beyond the limit tolerance.

  The present invention has been made in view of such technical problems, and the air mixing rate into the oil due to the viscosity of the new oil and the old oil due to the oil temperature and the aging deterioration of the antifoaming agent added to the oil. Predicting that the increase will cause the oil pump efficiency to decrease and the oil temperature will rise above the allowable upper limit temperature, and increase the oil temperature at an appropriate time before the oil temperature rises above the allowable upper limit temperature. The purpose is to start high oil temperature control to suppress. That is, the purpose is to minimize the deterioration of the running performance of the vehicle by appropriately adjusting the time and degree of high oil temperature control regardless of new oil or old oil, and to reduce the uncomfortable feeling given to the driver.

  According to an aspect of the present invention, there is provided an automatic transmission that shifts an output rotation of an engine, an oil pump that pumps oil toward components of the automatic transmission, and a suction port pressure of the oil pump that is detected A hydraulic pressure sensor that determines whether the suction port pressure has fallen below a lower limit, and an engine and the automatic transmission when it is determined that the suction port pressure has fallen below the lower limit. There is provided an automatic transmission comprising an oil temperature rise suppression means for controlling at least one of the machines to suppress an increase in oil temperature.

  Further, a high oil temperature control method for an automatic transmission corresponding to this is provided.

  When the suction port pressure falls below the lower limit value, the oil temperature has not risen above the allowable upper limit temperature. Therefore, if control of the engine or automatic transmission to suppress the oil temperature rise is started when the suction port pressure becomes lower than the lower limit value, the control is started at an appropriate timing regardless of new oil or old oil. It ’s done. In other words, the new oil with a relatively short mileage, which has a sufficient defoaming effect without oil deterioration, results in a longer high-speed operation time and control than the old oil. Since the starting oil temperature can also be on the high oil temperature side, rebound to the power performance and driving performance of the vehicle can be minimized.

1 is a schematic configuration diagram of a vehicle equipped with an automatic transmission according to an embodiment of the present invention. It is a circuit diagram of an oil pump. It is the table which showed the relationship between the suction port pressure and the air content rate of oil. It is the flowchart which showed the content of the high oil temperature control by a transmission controller. It is the flowchart which showed the content of the measurement permission condition judgment process in high oil temperature control. It is a table for setting an upper limit rotation speed and an upper limit torque of an engine.

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

  FIG. 1 is a schematic configuration diagram of a vehicle equipped with an automatic transmission according to an embodiment of the present invention. This vehicle includes an engine 1 as a power source. Output rotation of the engine 1 is via a torque converter 2 with a lock-up clutch, a first gear train 3, a continuously variable transmission (hereinafter simply referred to as "transmission 4"), a second gear train 5, and a differential 6. Is transmitted to the drive wheel 7. The second gear train 5 is provided with a parking mechanism 8 that mechanically locks the output shaft of the transmission 4 at the time of parking.

  The transmission 4 is provided with an oil pump 10 that is driven using part of the power of the engine 1. Further, the transmission 4 controls the hydraulic control circuit 11 and the hydraulic control circuit 11 that regulates the hydraulic pressure from the oil pump 10 (hereinafter referred to as “line pressure PL”) and supplies the hydraulic pressure to each part of the transmission 4. A transmission controller 12 is provided, and an oil cooler 13 that cools the oil of the transmission 4 is provided.

  The transmission 4 includes a variator 20 that is a belt-type continuously variable transmission mechanism, and an auxiliary transmission mechanism 30 that is provided in series with the variator 20.

  The variator 20 includes a primary pulley 21, a secondary pulley 22, and a V belt 23 that is wound around the pulleys 21 and 22. Each of the pulleys 21 and 22 includes a fixed conical plate, a movable conical plate that is arranged with a sheave surface facing the fixed conical plate, and forms a V-groove between the fixed conical plate, and the movable conical plate. The hydraulic cylinders 23a and 23b are provided on the back surface of the movable cylinder to displace the movable conical plate in the axial direction. When the hydraulic pressure supplied to the hydraulic cylinders 23a and 23b is adjusted, the width of the V groove changes, the contact radius between the V belt 23 and each pulley 21 and 22 changes, and the transmission ratio of the variator 20 changes steplessly. .

  The subtransmission mechanism 30 is a transmission mechanism having two forward speeds and one reverse speed. The subtransmission mechanism 30 includes a plurality of planetary gear mechanisms and a plurality of frictional engagement elements. When the engagement / release state of the plurality of frictional engagement elements is changed, the gear position of the auxiliary transmission mechanism 30 is changed.

  The transmission controller 12 includes a CPU, a storage device such as a RAM / ROM, an input / output interface, and the like.

  The transmission controller 12 detects an accelerator opening sensor 41 that detects an accelerator opening APO that is an operation amount of an accelerator pedal, an output signal of a rotation speed sensor 42 that detects an input rotation speed of the transmission 4, and a vehicle speed VSP. Vehicle speed sensor 43, line pressure sensor 44 for detecting the line pressure PL, inhibitor switch 45 for detecting the position of the select lever, brake switch 46 for detecting the operation state (ON / OFF) of the brake pedal, and suction port pressure of the oil pump 10 Output signals such as an oil pressure sensor 47 that detects Pin and an oil temperature sensor 48 that detects the oil temperature of the transmission 4 are input.

  The storage device stores a transmission control program for the transmission 4, a program for high oil temperature control, which will be described later, threshold values used in these programs, a table, and the like. The CPU reads and executes a program stored in the storage device, performs various arithmetic processes on various signals input to the transmission controller 12 to generate a control signal, and generates the generated signal as a hydraulic control circuit 11. Output to. Various values used by the CPU in the calculation process and the calculation results are appropriately stored in the storage device.

  The hydraulic control circuit 11 includes a plurality of flow paths and a plurality of hydraulic control valves. The hydraulic control circuit 11 controls a plurality of hydraulic control valves based on a control signal from the transmission controller 12 to switch the hydraulic pressure supply path and uses the line pressure PL sent from the oil pump 10 as a source pressure. The hydraulic pressure is adjusted and supplied to each part of the transmission 4. As a result, the gear ratio of the variator 20 and the gear position of the subtransmission mechanism 30 are changed, and the transmission 4 is shifted.

  The oil cooler 13 is a heat exchanger that cools the oil of the transmission 4 by heat exchange with the cooling water, and the cooled oil is supplied to the lubricating portion of the transmission 4.

  FIG. 2 is a circuit diagram of the oil pump 10.

  When driven by the power of the engine 1, the oil pump 10 sucks oil from the oil pan 15, sucks it from the suction port 10in, and pumps the oil to the discharge side. The oil pump 10 is a variable displacement type, and the displacement can be arbitrarily adjusted by displacing the actuator 10 a based on a signal from the hydraulic control circuit 11. A throttle 14 is provided on the discharge side of the oil pump 10, and a part of the oil between the oil pump 10 and the throttle 14 is returned to the suction side, so that the oil pump 10 can be reduced in size and reduced in friction. ing.

  A spool valve 16 is provided on the suction side of the oil pump 10. The pressure returned from the discharge side acts on both ends of the spool valve 16, and the biasing force of the spring 16s acts on one end, and the spool valve 16 automatically opens and closes due to the balance between them. Specifically, when the pressure returned from the discharge side is lower than the threshold value, the spool valve 16 is closed and the communication between the suction side and the discharge side is blocked, whereas the pressure returned from the discharge side is When the threshold value is exceeded, the spool valve 16 opens, the suction side and the discharge side communicate with each other, and a part of the oil on the discharge side is returned to the suction port 10in.

  The suction port 10in is provided with a hydraulic pressure sensor 47 that detects the hydraulic pressure of the suction port 10in (hereinafter referred to as “suction port pressure Pin”). The output signal of the hydraulic sensor 47 is input to the transmission controller 12.

  Incidentally, in the transmission 4, it is important to appropriately manage the oil temperature. This is because when the oil temperature rises above the allowable upper limit temperature (for example, 130 ° C.), the viscosity of the oil decreases, the operation of the hydraulic control valve in the hydraulic control circuit 11, the operation of the variator 20, and the auxiliary transmission mechanism 30. This is because it affects the fastening / release of the constituent frictional fastening elements, lubrication and cooling of the components.

  However, even if the oil temperature is monitored directly or indirectly and the output of the engine 1 is limited after the oil temperature exceeds the allowable upper limit temperature, the amount of air in the oil that causes an increase in the oil temperature at that time. Has already increased, and it is necessary to implement a significant output restriction of the engine 1 over a long period of time before the oil temperature falls below the allowable upper limit temperature, and the driver feels uncomfortable.

  Here, the rise of the oil temperature exceeding the allowable upper limit temperature occurs by the following mechanism.

  (1) The oil is agitated when a rotating body such as a gear of the transmission 4 rotates at a high speed during continuous high-speed traveling or the like.

  (2) Oil is mixed with air by stirring oil, and the air content rate of oil rises.

  (3) When the air content rate of oil rises, the volume of oil increases and the oil level rises, the oil is further stirred, and the air content rate of oil further rises. As shown in FIG. 3, there is a strong correlation between the air content of oil and the suction port pressure Pin, and the suction port pressure Pin decreases as the air content of oil increases.

  (4) When the air content rate of the oil increases, the efficiency of the oil pump 10 decreases and the discharge amount of the oil pump 10 decreases. When the discharge amount of the oil pump 10 decreases, the suction amount of the oil pump 10 also decreases, so that the suction port pressure Pin decreases.

  (5) When the suction port pressure Pin becomes lower than a predetermined value, the air in the oil expands in the pressure chamber of the oil pump 10 and the oil pump 10 cannot be compressed irregularly, and the oil vibration (discharge pressure hunting) Will occur.

  (6) The spool valve 16 hunts due to the oil vibration, the amount of oil returned from the discharge side of the oil pump 10 to the suction side is reduced, and further becomes zero, and the discharge amount of the oil pump 10 is further reduced.

  (7) When this state is continued, the flow rate to the oil cooler 13 decreases, and the oil temperature rises above the allowable upper limit temperature.

  Therefore, in the present embodiment, focusing on the fact that the suction port pressure Pin decreases before the oil temperature rises above the allowable upper limit temperature, monitoring the suction port pressure Pin can prevent future oil temperature rise. As a result, the engine output limit was started before the oil temperature exceeded the allowable upper limit temperature.

  FIG. 4 is a flowchart showing the content of the high oil temperature control by the transmission controller 12. The contents of the high oil temperature control will be described with reference to this.

In S1, the transmission controller 12 determines the measurement permission condition for the suction port pressure Pin. The condition for permitting measurement of the suction port pressure Pin is determined according to the flowchart shown in FIG. Specifically, the following conditions:
-The brake switch 46 is OFF (S11)
-The select lever is not in the P or N range (S12)
-The select lever is not being operated (S13)
-There is no abnormality in sensors related to high oil temperature control such as the oil temperature sensor 47 (S14).
・ Vehicle speed VSP is higher than 20km / h (S15)
・ Oil temperature is higher than 40 ° C (S16)
-Gear ratio of transmission 4 is less than 1 (S17)
-The accelerator opening APO is larger than 5 deg (S18).
-The input rotational speed of the transmission 4 is higher than 1500 rpm (S19).
When all of these conditions are satisfied, it is determined that the measurement permission condition is satisfied (S20). When any one of the conditions is not satisfied, it is determined that the measurement permission condition is not satisfied (S21).

  Returning to FIG. 4, in S <b> 2, the transmission controller 12 determines whether a measurement permission condition for the suction port pressure Pin is satisfied. If it is determined that it is established, the process proceeds to S3.

  In S <b> 3, the transmission controller 12 reads the suction port pressure Pin detected by the hydraulic sensor 47.

  In S4, the transmission controller 12 determines whether the suction port pressure Pin is equal to or lower than the lower limit value δ. The lower limit value δ is the predetermined value at which the oil vibration starts to occur and is determined by experiment. If it is determined that the suction port pressure Pin is less than or equal to the lower limit value δ, the process proceeds to S5. If not, the process returns to S3, and the monitoring of the suction port pressure Pin is continued.

  In S5, the transmission controller 12 performs oil temperature rise suppression control. Specifically, the transmission controller 12 sets the upper limit rotational speed and upper limit torque of the engine 1 according to the suction port pressure Pin with reference to the table shown in FIG. 6, and outputs these to an engine controller (not shown). Thus, the output of the engine 1 is limited. Thereby, rotation of the rotating component of the transmission 4 is suppressed, and an increase in oil temperature is suppressed.

  In S6, the transmission controller 12 determines whether the suction port pressure Pin has become higher than the value δ1. The suction port pressure Pin value δ1 is set as a threshold value at which the oil temperature is sufficiently higher than the aforementioned lower limit value δ to be in a steady state. If the suction port pressure Pin is not higher than the value δ1, the process returns to S5, and the transmission controller 12 continues the oil temperature rise suppression control.

  When the suction port pressure Pin is higher than the value δ1, the process proceeds to S7, and the oil temperature rise suppression control is terminated.

  Therefore, according to the high oil temperature control, when the suction port pressure Pin becomes equal to or lower than the lower limit value δ, it is predicted that the discharge amount of the oil pump 10 will decrease and the oil temperature exceeding the allowable upper limit temperature will occur in the future. Then, the oil temperature rise suppression control is started. That is, according to the high oil temperature control, the oil temperature rise suppression control is started immediately before the oil temperature rises exceeding the allowable upper limit temperature.

  When the suction port pressure Pin becomes equal to or lower than the lower limit value δ, the oil temperature exceeding the allowable upper limit temperature has not yet risen. Therefore, if control of the engine or automatic transmission to suppress the oil temperature rise is started when the suction port pressure becomes lower than the lower limit value, the control is started at an appropriate timing regardless of new oil or old oil. It ’s done. As a result, the new oil with a relatively short mileage, which has a sufficient defoaming effect without oil deterioration, results in a longer high-speed operation time than the timing for switching to a higher oil temperature control than the old oil. The temperature also becomes the high oil temperature side, and the rebound to the power performance and the driving performance of the vehicle can be minimized (effect corresponding to claims 1 to 4).

  Also, the oil temperature rise characteristics differ depending on whether the oil deterioration (travel distance) and the amount of oil are excessive, so when performing high oil temperature control based on the oil temperature, It is necessary to perform control under the assumption that the oil is excessive. When the oil is not deteriorated or when the amount of oil is appropriate, the control is excessive.

  In this regard, according to the high oil temperature control based on the suction port pressure Pin, optimal control can be performed regardless of the degree of deterioration of the oil and the excessive amount of oil (effect corresponding to claims 1 to 4). .

  This is because oil with little deterioration has a high defoaming effect and the suction port pressure Pin is difficult to decrease, and when the amount of oil is excessive, the contact between the oil and the rotating element increases to increase the air content and the suction port pressure Pin. This is because the influence of the degree of deterioration of the oil and the excessive amount of oil is reflected in the suction port pressure Pin so that the oil pressure decreases.

  The embodiment of the present invention has been described above, but the above embodiment is merely one example of application of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. is not.

  For example, in the present embodiment, in the high oil temperature control, an increase in the oil temperature is suppressed by restricting the output of the engine 1, but the flow rate to the oil cooler 13 that changes the transmission ratio and the transmission pattern of the transmission 4 is changed. It is also possible to suppress an increase in the oil temperature by controlling the hydraulic control circuit 11 so as to increase.

  Further, the lower limit value δ is set to a hydraulic pressure at which oil vibration starts to occur when the suction port pressure Pin decreases, but the lower limit value δ is higher than the hydraulic pressure at which oil vibration starts to occur due to the decrease of the suction port pressure Pin. May be set. In this case, the oil temperature rise suppression control can be started at an earlier timing, and the uncomfortable feeling given to the driver by these controls can be further reduced.

4 ... Continuously variable transmission (automatic transmission)
DESCRIPTION OF SYMBOLS 10 ... Oil pump 11 ... Hydraulic control circuit 12 ... Transmission controller (Oil temperature rise suppression means)
13 ... Oil cooler 47 ... Hydraulic pressure sensor

Claims (4)

An automatic transmission that changes the output rotation of an engine,
An oil pump that pumps oil toward the components of the automatic transmission;
A hydraulic sensor for detecting a suction port pressure of the oil pump;
A suction port pressure drop determining means for determining whether the suction port pressure is lower than a lower limit;
An oil temperature rise suppression means for controlling an increase in oil temperature by controlling at least one of the engine and the automatic transmission when it is determined that the suction port pressure is less than or equal to the lower limit;
An automatic transmission characterized by comprising: The automatic transmission according to claim 1,
The lower limit value is a value equal to or higher than a hydraulic pressure at which oil vibration starts to occur due to a decrease in the suction port pressure.
An automatic transmission characterized by that. A high oil temperature control method for an automatic transmission that includes an oil pump that pumps oil toward components of the automatic transmission and that changes the output rotation of the engine,
Detecting the suction port pressure of the oil pump;
Determine whether the suction port pressure is below the lower limit,
When it is determined that the suction port pressure is equal to or lower than the lower limit value, an increase in oil temperature is suppressed by controlling at least one of the engine and the automatic transmission.
A high oil temperature control method for an automatic transmission. A high oil temperature control method for an automatic transmission according to claim 3,
The lower limit value is a value equal to or higher than a hydraulic pressure at which oil vibration starts to occur due to a decrease in the suction port pressure.
A high oil temperature control method for an automatic transmission.

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