JP4607833B2 - Hydraulic control device for belt type continuously variable transmission - Google Patents

Description

  The present invention relates to a hydraulic control device for a belt type continuously variable transmission.

Conventionally, there is a belt-type continuously variable transmission using a V-belt as an automatic transmission mounted on a vehicle. In a belt-type continuously variable transmission, a V-belt is sandwiched between a primary pulley and a secondary pulley whose groove width is variably controlled based on hydraulic pressure, and power is transmitted by the contact friction force.
Such a belt type continuously variable transmission obtains a thrust of a pulley according to an input torque and a gear ratio, converts this thrust into a hydraulic pressure based on a predetermined value such as a pressure receiving area of a secondary pulley and a primary pulley, As a target value of the primary pressure and the secondary pressure.

The belt-type continuously variable transmission is provided with an oil pan. The oil pressure in the oil pan is sucked up by an oil pump and pressurized to generate a line pressure as a base pressure of the primary pressure and the secondary pressure.
An example of such a belt type continuously variable transmission is disclosed in Patent Document 1.

Some oil pumps are arranged in the air in an automatic transmission.
Such an oil pump prevents the seizure of the rotating shaft by pressurizing the oil sucked from the oil pan and supplying a part of the pressurized oil to a bearing that supports the rotating shaft provided in itself. Yes.
In addition, there is an oil pump in which the amount of oil supplied as lubricating oil to a bearing increases as the hydraulic pressure discharged by itself increases.
An example of such an oil pump is described in Patent Document 2.
Japanese Patent Laid-Open No. 11-37237 JP 2005-61391 A

  However, since the engine and automatic transmission are not warmed immediately after the engine is started, the oil temperature in the automatic transmission is low and the viscosity of the oil is high, and the oil pump bearings placed in the air are sufficiently lubricated. There was a problem that it could not be performed, and there was a risk of malfunction due to insufficient amount of lubricating oil.

  Therefore, in view of such a problem, the present invention provides a belt type continuously variable transmission that can reliably lubricate a bearing of an oil pump disposed in the air even when the temperature of oil immediately after engine startup is low. An object is to provide a hydraulic control device.

  The present invention generates primary and secondary pulleys that sandwich the belt, and hydraulic pressure, and supplies a part of the oil discharged by itself to the bearing that supports the rotating shaft as lubricating oil, thereby increasing the discharge pressure. A set value of the line pressure generated from the discharge pressure of the oil pump as the base pressure of the primary pressure supplied to the primary pulley and the secondary pressure supplied to the secondary pulley, and the oil pump in which the amount of lubricating oil increases along with, And a CVT control unit for calculating a set value of the primary pressure and a set value of the secondary pressure. The CVT control unit sets the line pressure from the set value of the secondary pressure until the speed ratio becomes a predetermined speed ratio. In the hydraulic control device for the belt type continuously variable transmission that calculates the value, the temperature of the oil sucked by the oil pump The CVT control unit detects that the oil temperature is an extremely low temperature below the first predetermined temperature by the oil temperature sensor. In this case, after the engine is started, the secondary pressure set value is set at a predetermined change rate according to the engine speed until reaching the limit speed at which seizure occurs when the oil pump bearing is insufficiently lubricated. After the secondary pressure set value becomes the cryogenic set pressure, the secondary pressure set value is maintained at the cryogenic set pressure, and the oil temperature is equal to or higher than the second predetermined temperature higher than the first predetermined temperature. When the room temperature is reached, the secondary pressure set value is set as the secondary pressure set value when the oil temperature is in the normal temperature state.

  According to the present invention, when the oil temperature is extremely low, the secondary pressure set value is set to a cryogenic set pressure that is higher than when the oil temperature is in the normal temperature state. Even if the oil pump discharge pressure increases and the oil pressure is low and the viscosity of the oil is high, the amount of oil supplied to the bearing is ensured and lubricated. It can be done reliably.

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.
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.

  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 (hereinafter referred to as ECU) 21 that controls the engine 1 and exchanges information with each other. The CVT control unit 20 determines the gear ratio and the contact friction force from the input torque information from the ECU 21, the throttle opening (TVO) from the throttle opening sensor 24, the engine speed, and the like.

An oil pan (not shown) for accumulating oil in the transmission is attached to a lower position of the belt type continuously variable transmission 3, and an oil temperature sensor 25 for detecting the temperature of the oil in the oil pan is provided. The detection result by the oil temperature sensor 25 is input to the CVT control unit 20.
Furthermore, a water temperature sensor 28 for detecting the temperature of the cooling water for cooling the engine 1 is provided, and the detection result by the water temperature sensor 28 is input to the CVT control unit 20.
An inhibitor switch 23 for detecting the operation position of the shift lever is provided, and operation position information (hereinafter also referred to as a range signal) of the shift lever detected by the inhibitor switch 23 is input to the CVT control unit 20.

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 in accordance with a hydraulic pressure (hereinafter referred to as primary pressure) acting on the cylinder chamber 10c.
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 input torque input from the engine 1 is input to the transmission mechanism 5 via the torque converter 2 and the forward / reverse switching mechanism 4, 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.

A power take-out gear 71 is attached to the pump impeller 2A of the torque converter 2.
An oil pump 7 having a pump input gear 73 is disposed at a radially outer position of the power take-out gear 71.
The oil pump 7 is disposed in the air in the automatic transmission.
A chain 72 is stretched between the power take-out gear 71 and the pump input gear 73, and the rotation of the engine 1 is inputted to the oil pump 7 through the pump impeller 2 A, the power take-out gear 71 and the chain 72.

The oil pump 7 is driven by the power of the engine, sucks oil from the oil pan, pressurizes it, and supplies it to the hydraulic control unit 100.
In particular, the oil pump 7 lubricates the bearing 75 by supplying oil sucked from the oil pan to a bearing 75 that supports a rotating shaft that is a component of the oil pump 7.

Next, the hydraulic control of the primary pressure and the secondary pressure performed by the CVT control unit 20 using the hydraulic control unit 100 will be described.
The CVT control unit 20 calculates a primary pressure and a secondary pressure necessary for maintaining a predetermined gear ratio based on input torque information from the engine and the like.
The CVT control unit 20 uses the calculated secondary pressure as the line pressure.
The hydraulic control unit 100 is provided with a pressure regulating valve that regulates the hydraulic pressure output from the oil pump 7. The hydraulic control unit 100 outputs from the oil pump 7 so that the line pressure calculated by the CVT control unit 20 is obtained. The line pressure is generated by adjusting the hydraulic pressure.
The hydraulic control unit 100 generates a primary pressure and a secondary pressure by adjusting the line pressure.

Here, the belt type continuously variable transmission 3 requires a higher pressure for the secondary pressure than for the primary pressure.
Therefore, the CVT control unit 20 first calculates the necessary secondary pressure from the input torque from the engine torque, etc., calculates the line pressure based on the secondary pressure, and then outputs the calculated line pressure from the oil pump 7. Control the oil pressure.

Next, a procedure in which the CVT control unit 20 controls the secondary pressure after the engine is started will be described.
Since the line pressure is calculated based on the secondary pressure immediately after the engine is started, the secondary pressure is determined by the CVT control unit 20, and the hydraulic pressure of the secondary pressure is controlled by the hydraulic control unit 100, resulting in the oil pump 7. The discharge pressure is controlled.

FIG. 2 shows a secondary pressure control procedure performed by the CVT control unit 20.
In step 100 of FIG. 2, the CVT control unit 20 determines whether or not the low temperature start determination is established.
Specifically, when the oil temperature detected by the oil temperature sensor 25 is less than a predetermined value or the water temperature detected by the water temperature sensor 28 is less than a predetermined value, or when the rotational speed of the engine 1 is less than a predetermined value, the inhibitor When the operation position of the shift lever detected by the switch 23 is in the P (parking) range or the N (neutral) range, when all the conditions in the case where the oil temperature sensor 25 and the water temperature sensor 28 are not out of order are satisfied, It is determined that the low-temperature start determination is established.
When the low temperature start determination is established, the routine proceeds to step 101. When the low temperature start determination is not established, the process proceeds to step 109, and the secondary pressure control is performed when the oil temperature is normal temperature.

In step 101, the CVT control unit 20 determines whether or not the oil temperature detected by the oil temperature sensor 25 is an extremely low temperature lower than −20 ° C. (first predetermined temperature).
If the oil temperature is less than −20 ° C., the process proceeds to step 102, and if not, the process proceeds to step 104.
In step 102, the control for starting the secondary pressure at a cryogenic temperature is started.
The cryogenic start-up control is performed in parallel with the control shown in FIG. 2. Even during the cryogenic start-up control, the branch determination in step 103 in FIG. 2 is performed, and the determination result in step 103 is used. Therefore, the control at the start of cryogenic temperature is completed or continued.

Here, details of the cryogenic start-up control will be described.
FIG. 3 shows changes in the secondary pressure setting value that the CVT control unit 20 instructs the hydraulic control unit 100 separately for each oil temperature state. FIG. 4 shows a flow of control processing at the start of cryogenic temperature.
In step 200, the CVT control unit 20 has reached a speed at which it can be determined that the engine has started normally (hereinafter referred to as a start determination speed) since the vehicle ignition is turned on (time t1 in FIG. 3). Judge whether.
If the engine speed is equal to or higher than the start determination speed (time t2), the process proceeds to step 201, and if not, the process proceeds to step 204.

In step 204, the secondary pressure instructed to the hydraulic control unit 100 (hereinafter referred to as a secondary pressure set value) is set to zero and the process returns to step 200.
This eliminates the need for the oil pump 7 to generate hydraulic pressure when the engine is started, reduces the load on the pump, and allows the engine to be cranked efficiently.

After the engine speed becomes equal to or higher than the start determination speed (time t2), in step 201, the CVT control unit 20 controls the secondary pressure set value according to the engine speed.
This is to instruct the hydraulic control unit 100 of a secondary pressure value that gradually increases from a predetermined value as the engine speed increases.
The rising gradient of the secondary pressure set value is set so that the engine 1 does not stall due to the load of the oil pump 7 accompanying the increase in hydraulic pressure.

Here, as the oil pressure generated by the oil pump 7 increases, the amount of oil supplied to the bearing 75 as lubricating oil increases.
The oil pump 7 has a high oil viscosity when the pump discharge pressure is low and the oil temperature is lower than −20 ° C. Therefore, a bearing 75 that supports a rotating shaft provided with a sufficient amount of oil is provided. Can not be supplied to. Further, the oil pump 7 is assumed that seizure occurs at the bearing portion when the rotational speed of the engine 1 becomes 1800 rpm or more in a state where the bearing 75 is not sufficiently lubricated.

In order to supply a sufficient amount of oil as a lubricating oil to the bearing 75 of the oil pump 7 even when the viscosity of the oil whose temperature is lower than −20 ° C. is high, the oil pump 7 has a predetermined discharge higher than normal. It is necessary to output pressure.
In the belt-type continuously variable transmission 3 according to the present embodiment, this predetermined discharge pressure is, for example, a pressure when the oil pump 7 discharges a hydraulic pressure necessary to generate a hydraulic pressure of 2 MPa as a secondary pressure. .
Therefore, when the oil temperature is lower than −20 ° C., when the oil pump 7 is discharging the hydraulic pressure necessary to generate the hydraulic pressure of 2 MPa as the secondary pressure when the engine speed is 1800 rpm, The problem that the bearing 75 of the pump 7 is seized does not occur.

Therefore, in the secondary pressure control in step 201, the rising gradient of the secondary pressure set value after time t2 in FIG. 3 is set so that the secondary pressure set value reaches 2 MPa when the engine speed reaches 1800 rpm. .
In step 202, it is determined whether or not the secondary pressure set value has become 2 MPa. If the secondary pressure set value has become 2 MPa, the process proceeds to step 203. If not, the engine speed in step 201 is set. The control of the corresponding secondary pressure set value is continued.
After increasing the secondary pressure set value to 2 MPa, the CVT control unit 20 instructs a value of 2 MPa as the secondary pressure set value after time t4 in FIG.
This cryogenic start-up control is continued until it is determined in step 103 of FIG.

Returning to FIG. 2, in step 103, it is determined whether or not the oil temperature is less than −20 ° C.
When the oil temperature is no lower than −20 ° C., the cryogenic start-up control is terminated and the routine proceeds to step 105. On the other hand, when the oil temperature is less than −20 ° C., the process returns to step 102 and the control at the start of the cryogenic temperature is continued.

When it is determined in step 101 that the oil temperature is not lower than −20 ° C., in step 104, the CVT control unit 20 determines whether or not the oil temperature is a low temperature lower than 0 ° C. (second predetermined temperature).
When the oil temperature is less than 0 ° C., the process proceeds to step 105, and when the oil temperature is a room temperature that is 0 ° C. or higher, the process proceeds to step 109.
In step 105, the secondary pressure cold start control is started.
Note that the cold start control is performed in parallel with the control shown in FIG. 2. Even during the cold start control, the branch determination of steps 106 to 108 in FIG. 2 is performed, and the determination results of steps 106 to 108 are performed. Based on this, the cold start control is terminated or continued.

Here, details of the cold start control will be described.
FIG. 5 shows the flow of the low temperature start-up control process.
The processing in steps 300, 301, and 305 is the same as the processing in steps 200, 201, and 204 in FIG.
Note that the increase gradient of the secondary pressure set value to be increased according to the engine speed in the control of step 301 is the same as the increase gradient of the secondary pressure set value in step 201.
In step 302, it is determined whether or not the secondary pressure set value is 1.3 MPa. If the secondary pressure set value is 1.3 MPa, the process proceeds to step 303. The process in 301 is repeated.
After increasing the secondary pressure set value to 1.3 MPa, the CVT control unit 20 instructs a value of 1.3 MPa as the secondary pressure set value in step 303 after time t3 in FIG.
This low temperature start-up control is performed in steps 106 to 108 in FIG. 2, as will be described in detail later, but switching from the P range (or N range) to the D (forward) range or when the oil temperature is 0 ° C. or higher. It continues until it is judged that it became.

Returning to FIG. 2, in step 106, the CVT control unit 20 determines from the signal from the inhibitor switch 23 whether the driver has switched from the P range (or N range) to the D range.
If the shift range has been switched, the process proceeds to step 109, and if there is no switch, the process proceeds to step 107.
When the shift range is switched, the cold start control is terminated. As will be described in detail later, in step 109, the secondary pressure setting value is set to the secondary pressure setting value (0.7 MPa) that is instructed when the oil temperature is in the normal temperature state. .
Therefore, in FIG. 3, after the time t5 when the shift range is switched, 0.7 MPa is instructed as the secondary pressure set value.

In step 107, it is determined whether or not the oil temperature is lower than -20 ° C. On the other hand, if the oil temperature is not less than −20 ° C., the routine proceeds to step 108.
In step 108, it is determined whether or not the oil temperature is lower than 0 ° C. If the oil temperature is lower than 0 ° C., the process returns to step 105, and the low temperature starting control is continued. On the other hand, when the oil temperature is not lower than 0 ° C., the process proceeds to step 109, and the secondary pressure control is performed when the oil temperature is in the normal temperature state.

The secondary pressure control when the oil temperature is in the normal temperature state is to instruct 0.7 MPa as the secondary pressure set value after the rotation speed of the engine 1 becomes equal to or higher than the start determination rotation speed.
When the accelerator is depressed during the secondary pressure control at normal temperature, the CVT control unit 20 increases the secondary pressure set value according to the engine torque or the like.

Thus, when the oil temperature is less than −20 ° C., the control at the cryogenic start in step 102 is performed, and when the oil temperature is −20 ° C. or more and less than 0 ° C., the control at the low temperature start in step 105 is performed, Further, when the oil temperature is 0 ° C. or higher, secondary pressure control at normal temperature is performed.
If the shift from the P range to the D range is performed during the cold start control, the secondary pressure control is switched to the normal temperature. Further, during the cryogenic start-up control, the control shifts to the cold start-up control when the oil temperature becomes less than -20 degrees.

The present embodiment is configured as described above, and when the oil temperature is less than −20 ° C. which is an extremely low temperature state, the oil pressure of the oil pump 7 is controlled by controlling the secondary pressure setting value to be a high oil pressure (2 MPa). Since the amount of oil supplied to the bearing 75 increases as the discharge pressure increases, the bearing 75 of the oil pump 7 is sufficiently lubricated even when the engine speed increases to the seizing limit speed of the oil pump 7. The occurrence of seizure can be prevented.
When the oil temperature is -20 ° C. or higher and lower than 0 ° C., the secondary pressure setting value is 1.3 MPa, and the oil temperature is divided into three patterns of an extremely low temperature state, a low temperature state, and a normal temperature state. By changing it, the increase in the discharge pressure of the oil pump 7 can be made appropriate according to the state of the oil temperature, and the bearing 75 of the oil pump 7 can be lubricated reliably.

When the oil temperature is low, the oil viscosity is low compared to when the oil temperature is extremely low, and the oil pump 7 is easily lubricated. Therefore, when the shift is switched from the P range or the N range to the D range. The low temperature start-up control is terminated, and the secondary pressure set value is instructed to the secondary pressure set value (0.7 MPa) when the oil temperature is in the normal temperature state. Fuel efficiency can be improved.
In addition, after the ignition is turned on (time t1 in FIG. 3), the secondary pressure setting value is not increased until the engine speed reaches the start determination rotation speed, so that the oil pump 7 is driven when the engine 1 is started. The load is eliminated and the starting performance of the engine 1 can be improved.

It is a figure which shows schematic structure of a belt-type continuously variable transmission. It is a figure which shows the control procedure of a secondary pressure. It is a figure which shows the change of the secondary pressure setting value in each oil temperature state. It is a figure which shows the flow of a process of control at the time of a cryogenic start. It is a figure which shows the flow of a process of control at the time of low temperature start.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Torque converter 3 Belt type continuously variable transmission 4 Forward / reverse switching mechanism 5 Transmission mechanism 7 Oil pump 10 Primary pulley 11 Secondary pulley 12 V belt 20 CVT control unit 21 Engine control unit (ECU)
23 Inhibitor switch 24 Throttle opening sensor 25 Oil temperature sensor 28 Water temperature sensor 71 Power take-out gear 72 Chain 73 Pump input gear 75 Bearing 100 Hydraulic control unit

Claims (4)

A primary pulley and a secondary pulley that sandwich the belt;
An oil pump that generates oil pressure, supplies a part of the oil discharged to a bearing supporting its own rotating shaft as a lubricating oil, and the amount of the lubricating oil increases as the discharge pressure increases;
A set value of the line pressure generated from the discharge pressure of the oil pump is calculated as a base pressure of the primary pressure supplied to the primary pulley and the secondary pressure supplied to the secondary pulley, and further, the set value of the primary pressure and the A CVT control unit for calculating a set value of the secondary pressure,
The CVT control unit is a hydraulic control device in a belt-type continuously variable transmission that calculates the set value of the line pressure from the set value of the secondary pressure until the speed ratio becomes a predetermined speed ratio.
An oil temperature sensor for detecting the temperature of oil sucked by the oil pump;
An engine speed sensor for detecting the engine speed,
The CVT control unit
When it is detected by the oil temperature sensor that the oil temperature is an extremely low temperature below the first predetermined temperature,
After starting the engine, until the limit rotational speed at which seizure occurs when the lubrication of the bearing of the oil pump is insufficient,
Increasing the secondary pressure set value at a predetermined rate of change according to the engine speed,
After the secondary pressure set value becomes the cryogenic set pressure, the secondary pressure set value is maintained at the cryogenic set pressure,
When the oil temperature reaches a room temperature equal to or higher than a second predetermined temperature higher than the first predetermined temperature, the secondary pressure setting value is set as a secondary pressure setting value when the oil temperature is in a normal temperature state. A hydraulic control device for a belt type continuously variable transmission. The CVT control unit
When it is detected by the oil temperature sensor that the oil temperature is lower than the second predetermined temperature and the temperature is lower than the first predetermined temperature,
After the engine is started, a predetermined value corresponding to the rotational speed of the engine is set such that the oil temperature is higher than the secondary pressure set value in the normal temperature state and lower than the cryogenic set pressure. 2. The secondary pressure set value is increased at a rate of change, and after the secondary pressure set value becomes the low temperature set pressure, the secondary pressure set value is maintained at the low temperature set pressure. The hydraulic control apparatus in the belt-type continuously variable transmission described in 1. It has an inhibitor switch that detects the range position of the transmission,
When the CVT control unit has set a low temperature set pressure as the secondary pressure set value,
When a shift switch from the parking range to the forward range is detected by the inhibitor switch, or when a shift switch from the neutral range to the forward range is detected,
The hydraulic control device for a belt-type continuously variable transmission according to claim 2, wherein the secondary pressure set value is a secondary pressure set value when the oil temperature is in a normal temperature state. The CVT control unit
The belt-type continuously variable transmission according to any one of claims 1 to 3, wherein the secondary pressure set value is increased at a predetermined rate of change after the engine speed reaches or exceeds a predetermined speed. Hydraulic control device in the machine.

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