JP4246982B2 - Control device for belt type continuously variable transmission - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to the technical field of control devices for belt type continuously variable transmissions.
[0002]
[Prior art]
In the conventional belt type continuously variable transmission control device, the primary pulley is provided with a primary rotation speed sensor, the secondary pulley is provided with a secondary rotation speed sensor, and the external teeth provided on the peripheral portions of both pulleys are read by the sensor, The primary speed and the secondary speed are detected, and the actual gear ratio is calculated from these values. When the actual transmission ratio or the transmission speed becomes a value that cannot be taken by the mechanism, it is determined that the belt is slipping, and control is performed to increase the pulley clamp pressure by correcting the line pressure to be increased (for example, patent document). 1).
[Patent Document 1]
JP-A-62-68142 (pages 1, 2)
[0003]
[Problems to be solved by the invention]
However, in the above conventional belt type continuously variable transmission control device, a gear ratio larger than the maximum gear ratio that can be instantaneously detected by the mechanism is detected even when belt slip does not occur for the following reason. Therefore, there is a risk of erroneously determining the occurrence of belt slip.
(1) When calculating the actual gear ratio, detection delay occurs because a plurality of processes such as detection pulse filtering are required.
(2) The sensor detection error increases at low speeds such as when starting.
[0004]
As a result, when engine torque output restriction is performed in a situation where the occurrence of belt slip is erroneously determined as described above, there is a problem that startability is reduced. In addition, when the line pressure is corrected to be increased, the pulley clamp pressure becomes excessively high, and there is a problem that the belt durability is lowered.
[0005]
On the other hand, the above-mentioned problem is not solved even if the shift speed is calculated from the speed ratio calculated as described above and belt slippage is detected from this shift speed.
[0006]
The present invention has been made paying attention to the above-mentioned problem, and an object of the present invention is to provide a control device for a belt type continuously variable transmission capable of improving the belt durability by improving the accuracy of belt slip determination. It is to provide.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, a primary pulley having a variable pulley interval is provided on the main shaft on the engine side, and a variable pulley interval is provided on the auxiliary shaft on the wheel side that is arranged in parallel with the main shaft. A continuously variable transmission in which a secondary belt is provided, a drive belt is wound between both pulleys, and the oil pressure of both pulleys is controlled to change the ratio of the winding diameter of the drive belt to both pulleys to change continuously. , The gear ratio calculating means for calculating the gear ratio based on the primary pulley rotation speed and the secondary pulley rotation speed, and when the gear ratio value is continuously deviated from the gear ratio area on the mechanism for a predetermined time, Belt slip judging means for judging that it has occurred, Acceleration detecting means for detecting the acceleration of the vehicle; The belt slip judging means is The predetermined time is set longer as the detected acceleration is larger. It is characterized by that.
[0008]
In the invention according to claim 2, The belt-type continuously variable transmission control device according to claim 1, further comprising belt protection control means for performing belt protection control when it is determined by the belt slip determination means that belt slip has occurred. It is characterized by that.
[0009]
In the invention according to claim 3, the claim 2 In the control device for the belt-type continuously variable transmission described in The belt protection control is a control that regulates the upper limit of the engine torque. It is characterized by that.
[0010]
In the invention according to claim 4, the claim 2 In the control device for the belt-type continuously variable transmission described in The belt protection control is an upshift It is characterized by that.
[0011]
In the invention according to claim 5, the claim 2 In the control device for the belt-type continuously variable transmission described in The belt protection control is a control that regulates the upper limit of the engine speed. It is characterized by that.
[0012]
In the invention according to claim 6, the claim 2 In the control device for the belt-type continuously variable transmission described in The belt protection control is a control for increasing the engine idle speed when the vehicle is stopped by a predetermined speed. It is characterized by that.
[0014]
【The invention's effect】
According to the first aspect of the present invention, the belt slip judging means causes belt slip when the speed ratio value calculated by the speed ratio calculating means continuously deviates from the speed ratio area on the mechanism for a predetermined time. Judge that Therefore, even if belt slip does not occur, belt slip judgment is not erroneously detected when the maximum gear ratio instantaneously becomes a value that cannot be taken by the mechanism due to sensor detection error, etc. Accuracy can be increased.
[0016]
Ma Claim 1 In the invention described in (2), it is possible to achieve both prevention of erroneous detection and improvement of belt durability by setting a longer predetermined time for determining the state where the maximum gear ratio is exceeded as the acceleration increases.
Claim 2 In the invention described in (1), the belt protection control means performs belt protection control when it is determined by the belt slip determination means that belt slip has occurred. On the other hand, if it is not determined that belt slip has occurred, belt protection control is not performed. Therefore, belt durability can be suppressed by suppressing belt slip.
[0017]
Claim 3 In the invention described in (1), since the upper limit of the input torque to the primary pulley is regulated by regulating the upper limit of the engine torque, the input torque can be reliably suppressed and belt slip can be prevented.
[0018]
Claim 4 In the invention described in (2), it is possible to increase the input torque that can be transmitted by upshifting, and to prevent belt slippage.
[0019]
Claim 5 In the invention described in, it can be considered that the upper limit of the engine torque is limited by limiting the upper limit of the engine speed. Therefore, it is possible to prevent the belt slip by reliably suppressing the input torque to the primary pulley.
[0020]
Claim 6 In the invention described in (1), the discharge amount of the oil pump driven by the engine can be ensured by increasing the engine idle speed by a predetermined speed when the vehicle is stopped. Therefore, it is possible to ensure a sufficient pulley clamp pressure even at the time of starting when a large load is applied to the pulley, and to prevent belt slippage.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a control system of an engine and a belt type continuously variable transmission 3 (hereinafter abbreviated as CVT) in the embodiment.
[0023]
1 is a torque converter, 2 is a lock-up clutch, 3 is a CVT, 4 is a primary speed sensor, 5 is a secondary speed sensor, 6 is a hydraulic control valve unit, 8 is an oil pump driven by the engine, and 9 is CVT control Unit 10 is an accelerator opening sensor, 11 is an oil temperature sensor, 18 is an engine, 19 is an engine control unit (hereinafter abbreviated as ECU), 16 is an engine speed sensor, and 17 is a throttle opening sensor.
[0024]
The engine 18 is provided with a plurality of injectors for injecting fuel and an electronically controlled throttle operated by an electric actuator. A fuel injection command and an electronically controlled throttle opening command for each injector are issued by the ECU 19.
[0025]
The ECU 19 basically detects a signal from the engine speed sensor 16 that detects the engine speed Ne, a signal from the accelerator opening sensor 10 that detects the accelerator pedal operation amount APS of the driver, and a throttle opening corresponding to the engine load. A signal from the throttle opening sensor 17 for detecting the degree TVO is inputted, and the fuel injection is cut until the output torque control command, the idling engine speed control command of the engine when the vehicle is stopped, and the engine speed is reduced to a predetermined engine speed when decelerating. Outputs a fuel cut control command, etc.
[0026]
A torque converter 1 is connected to the engine output shaft as a rotation transmission mechanism, and a lockup clutch 2 that directly connects the engine and the CVT 3 is provided. The output side of the torque converter 1 is connected to the ring gear 21 of the forward / reverse switching mechanism 20. The forward / reverse switching mechanism 20 includes a planetary gear mechanism including a ring gear 21 connected to the engine output shaft 12, a pinion carrier 22, and a sun gear 23 connected to the transmission input shaft 13. The pinion carrier 22 is provided with a reverse brake 24 that fixes the pinion carrier 22 to the transmission case, and a forward clutch 25 that integrally connects the transmission input shaft 13 and the pinion carrier 22.
[0027]
A primary pulley 30 a of the CVT 3 is provided at the end of the transmission input shaft 13. The CVT 3 includes the primary pulley 30a, the secondary pulley 30b, a belt 34 that transmits the rotational force of the primary pulley 30a to the secondary pulley 30b, and the like. The primary pulley 30 a has a fixed conical plate 31 that rotates integrally with the transmission input shaft 13, a V-shaped pulley groove that is disposed opposite to the fixed conical plate 31, and is shifted by hydraulic pressure that acts on the primary pulley cylinder chamber 33. The movable conical plate 32 is movable in the axial direction of the machine input shaft 13.
[0028]
The secondary pulley 30 b is provided on the driven shaft 38. The secondary pulley 30 b has a fixed conical plate 35 that rotates integrally with the driven shaft 38, a V-shaped pulley groove that is disposed opposite to the fixed conical plate 35, and is driven by hydraulic pressure that acts on the secondary pulley cylinder chamber 37. The movable conical plate 36 is movable in the axial direction.
[0029]
A drive gear (not shown) is fixed to the driven shaft 38. The drive gear is a pinion, a final gear, or a differential gear provided on the idler shaft. Drive the drive shaft to the drive wheels.
[0030]
The rotational force input from the engine output shaft 12 to the CVT 3 is transmitted to the CVT 13 via the torque converter 1 and the forward / reverse switching mechanism 20. The rotational force of the transmission input shaft 13 is transmitted to the differential device via the primary pulley 30a, belt 34, secondary pulley 30b, driven shaft 38, drive gear, idler gear, idler shaft, pinion, and final gear.
[0031]
During the power transmission as described above, by moving the movable conical plate 32 of the primary pulley 30a and the movable conical plate 36 of the secondary pulley 30b in the axial direction to change the contact position radius with the belt 34, the primary pulley 30a The rotation ratio between the secondary pulley 30b, that is, the gear ratio can be changed. Such control for changing the width of the V-shaped pulley groove is performed by hydraulic control to the primary pulley cylinder chamber 33 or the secondary pulley cylinder chamber 37 via the CVT control unit 9.
[0032]
The CVT control unit 9 includes a primary rotational speed N from the primary rotational speed sensor 4. _pri Secondary rotational speed N from secondary rotational speed sensor 5 _sec Primary pulley pressure P from primary pressure sensor 14 _pri Secondary pulley pressure P from secondary pressure sensor 15 _sec Etc. are input. In addition, information such as vehicle body acceleration and sensor values calculated from the driven wheel sensor 17a is transmitted / received through communication with the ECU 19, and a control signal is calculated based on these input signals to the hydraulic control valve unit 6. Output a control signal.
[0033]
The hydraulic control valve unit 6 is driven by each electronic control valve and a step motor 54 described later based on a control signal calculated by the CVT control unit 9, and control pressure is applied to the primary pulley cylinder chamber 33 and the secondary pulley cylinder chamber 37. Shift control is performed by supplying.
[0034]
FIG. 2 is a circuit diagram showing a hydraulic circuit of the belt type continuously variable transmission according to the embodiment.
A pressure regulator valve 40 adjusts the discharge pressure of the oil pump 8 supplied from the oil passage 41 as a line pressure (pulley clamp pressure). An oil passage 42 communicates with the oil passage 41. The oil passage 42 is connected to a transmission control valve 50 that supplies a control oil pressure to the primary pulley cylinder chamber 33 of the CVT 3, and a pulley pressure supply oil passage 48 that supplies a clamp pressure for clamping the belt 34 to the secondary pulley cylinder chamber 37. It is connected via a pressure reducing valve 49. The oil passage 43 connected to the oil passage 42 supplies the original pressure of the pilot valve 55.
[0035]
The pressure reducing valve 49 drives a solenoid by a control signal from the CVT control unit 9, and a secondary pulley pressure P by feedback control (closed loop control). _sec To control.
[0036]
The transmission control valve 50 is controlled by a control signal from a suction port 50 a connected to the oil passage 42, a supply port 50 b for supplying hydraulic pressure to the primary pulley cylinder chamber 33, a drain port 50 c for draining hydraulic pressure, and a CVT control unit 9. An operating step motor 54 is connected by a link 52, thereby constituting a mechanical feedback mechanism.
[0037]
When the spool 50d is moved by the drive of the step motor 52 and the hydraulic pressure is supplied to the primary pulley cylinder chamber 33, the movable pulley is moved by the change of the transmission gear ratio, and the movement of the spool 50d is driven again by this movement. By driving in the reverse direction, the supply of hydraulic pressure stops, so that a desired gear ratio can be obtained. On the other hand, when the spool motor 50d is moved by the drive of the step motor 52 and the hydraulic pressure in the primary pulley cylinder chamber 33 is discharged, the movable pulley is moved by the change of the gear ratio, and this movement again reverses the direction of the driving of the spool 50d. The hydraulic pressure is stopped by driving to a desired speed ratio.
[0038]
The oil pressure drained from the pressure regulator valve 40 is supplied to the clutch regulator valve 60 through the oil passage 46. In this way, by adjusting the hydraulic pressure lower than the hydraulic pressure generated by the pressure regulator valve 40 by the clutch regulator valve 60, the hydraulic pressure supplied as the engagement pressure of the forward clutch 25 is reduced. Riku The configuration does not exceed the lamp pressure.
[0039]
The oil passage 46 communicates with the oil passage 42 and communicates with an oil passage 44 having an orifice 45. The clutch regulator valve 60 regulates the oil pressure in the oil passage 46 and the oil passage 61. The oil pressure in the oil passage 61 is supplied to the select switching valve 80 and the select control valve 90.
[0040]
A pilot valve 55 sets a constant supply pressure to the lockup solenoid 71 and the select switching solenoid 70 via the oil passage 56. The output pressure of the select switching solenoid 70 is supplied from the oil passage 73 to the select switching valve 80 to control the operation of the select switching valve 80. The output pressure of the lockup solenoid 71 is supplied from the oil passage 72 to the select switching valve 80.
[0041]
Reference numeral 80 denotes a select switching valve, which is operated by a select switching solenoid 70. An oil passage 72 that supplies a signal pressure from the lockup solenoid 71 is connected to the select switching valve 80 as an input port. An oil passage 61 that is regulated by the clutch regulator valve 60 is connected to the select switching valve 80. A regulated oil passage 93 is connected. Further, an oil passage 81 for supplying forward clutch pressure is connected to the manual valve 100 as an output port, and an oil passage 82 for supplying hydraulic pressure to a lock-up clutch control valve (not shown) is connected to the spool 92 of the select control valve 90. An oil passage 83 for supplying hydraulic pressure for operating the oil pressure is connected, and a drain oil passage 84 for draining the hydraulic pressure is connected.
[0042]
A select control valve 90 is operated by a lockup solenoid 71 supplied from an oil passage 83. Connected to the select control valve 90 is an oil passage 62 that is regulated by the clutch regulator valve 60 and an oil passage 83 that supplies the signal pressure of the lockup solenoid 71 as an input port. Then, the hydraulic pressure is regulated by controlling the communication state of the oil passage 62 and the oil passage 93.
[0043]
Next, the operation will be described.
[Belt slip judgment control processing]
FIG. 3 is a flowchart showing the flow of the belt slip determination control process in the CVT control unit 9.
[0044]
In step S101, the primary rotational speed N detected by the primary rotational speed sensor 4 _pri Is a predetermined value, for example, 500 rpm or more. If it is 500 rpm or more, the process proceeds to step S102, and if it is less than 500 rpm, the process proceeds to step S107. This is the primary speed N _pri If the rotation speed is 500 rpm or less, the detection noise of the primary rotation speed sensor 4 becomes large. In this case, slip determination is not performed, so that erroneous determination of belt slip is reduced.
[0045]
In step S102, the detected primary rotational speed Npri is determined on the mechanism (mechanism Target To possible gear shift In ratio It is determined whether or not there is a primary rotational speed Npri equal to or greater than a value obtained by multiplying the maximum speed ratio 2.7 by the secondary rotational speed Nsec. Primary rotational speed Npri is equal to or greater than maximum speed ratio 2.7 multiplied by secondary rotational speed Nsec. Place If the primary rotational speed Npri is smaller than the value obtained by multiplying the maximum speed ratio 2.7 by the secondary rotational speed Nsec, the process proceeds to step S107.
[0046]
In step S103, whether or not the belt slip occurs while the oil pump 8 is operating normally is determined based on whether or not the engine speed Ne is a predetermined value, for example, 600 rpm or more. When the engine speed Ne is 600 rpm or more, the process proceeds to step S104, and when the engine speed Ne is smaller than 600 rpm, the process proceeds to step S107.
[0047]
In step S104, the timer is counted down.
[0048]
In step S105, the primary rotational speed N _pri It is determined from whether or not the countdown of the timer has ended whether or not a state where the maximum transmission ratio that can be taken by the mechanism has exceeded a predetermined time has continued. Note that this predetermined time is set to a time during which a reading error that occurs when the vehicle can normally take acceleration can be excluded from the belt slip determination. For example, the predetermined time is set to 0.2 sec. For example, the driven wheel sensor 17a The predetermined time may be changed based on the acceleration detected from the above. In this case, as shown in FIG. 6, the longer the predetermined time is, the shorter the acceleration is, and the shorter is the shorter the acceleration, thereby making it possible to both prevent false detection and improve the durability of the belt. If the countdown has been completed, the process proceeds to step S106. If the countdown has not been completed, the present control is terminated.
[0049]
In step S106, it is determined that belt slip has occurred, belt protection control is performed, and this control is terminated.
[0050]
In step S107, the timer is initialized and this control is terminated.
[0051]
[Belt protection control processing when belt slippage is detected]
FIG. 4 is a flowchart showing the flow of the belt protection control process at the time of belt slip determination in the CVT control unit 9.
[0052]
In step S201, the target position of the step motor 54 is set to the overdrive side operation limit.
[0053]
In step S202, the driving speed of the step motor 54 is set to a predetermined value.
[0054]
In step S203, a command for limiting the engine speed Ne to a predetermined value or less is output to the ECU 19.
[0055]
In step S204, a command for increasing the idle speed to a predetermined value is output to the ECU 19.
[0056]
In step S205, it is determined whether or not the actual position of the step motor 54 has reached the overdrive side operation limit. If it is the operation limit, the process proceeds to step S206, and if it is not the operation limit, the process proceeds to step S209.
[0057]
In step S206, the timer is counted down.
[0058]
In step S207, whether or not a predetermined time has elapsed since the actual position of the step motor 54 has reached the overdrive side operation limit, that is, after the instruction to set the gear ratio to the maximum Hi is output, the pulley moves to the overdrive side operation limit. Whether it has moved or not is determined from whether or not the timer countdown has ended. If the countdown has been completed, the process proceeds to step S208. If the countdown has not been completed, the process proceeds to step S209.
[0059]
In step S208, a command to set the torque limit amount of the engine 20 to 70 Nm is output to the ECU 19, and this control is terminated.
[0060]
In step S209, a command to set the torque limit amount of the engine 20 to 50 Nm is output to the ECU 19, and this control is terminated.
[0061]
[Belt protection control when judging belt slippage]
FIG. 5 is a time chart showing the belt protection control operation at the time of belt slip determination.
[0062]
At t1, the pulley ratio (speed ratio) exceeds the maximum speed ratio on the mechanism. At this time, in the flowchart of FIG. 3, the flow proceeds from step S101 to step S102 to step S103 to step S104 to step S105.
[0063]
That is, it is determined in step S101 that the primary rotational speed Npri is 500 rpm or more, and in step S102, the primary rotational speed Npri is determined to be greater than or equal to the maximum speed ratio 2.7 that can be taken by the mechanism. Subsequently, it is determined in step S103 that the engine speed Ne is 600 rpm or more, the timer is counted down in step S104, and it is determined in step S105 that the countdown has not ended.
[0064]
At t2, since 0.2 sec which is a predetermined time has elapsed since the gear ratio exceeds the maximum gear ratio on the mechanism, in the flowchart of FIG. 3, go to step S101 → step S102 → step S103 → step S104 → step S105 → step S106. It will be a flow that goes forward.
[0065]
That is, it is determined in step S105 that the countdown has been completed, and in step S106, it is determined that belt slip has occurred, and belt holding control is performed. In the belt holding control, the flow proceeds from step S201 to step S202 to step S203 to step S204 to step S205 to step S209 in the flowchart of FIG.
[0066]
That is, the target position of the step motor 54 is set to the overdrive side operation limit in step S201, and the drive speed of the step motor 54 is set to a predetermined value in step S202. Subsequently, in step S203, a command for limiting the engine speed Ne to a predetermined value or less is output to the ECU 19, and in step S204, a command for increasing the idle speed to a predetermined value is output to the ECU 19. Next, in step S205, it is determined that the actual position of the step motor 54 has not reached the overdrive side operation limit, and in step S209, a command to set the torque limit amount of the engine 20 to 50 Nm is output to the ECU 19.
[0067]
Here, the overdrive-side operation limit means a position where the step motor 54 is moved further to the upshift side than the position of the minimum gear ratio in terms of the gear ratio. The reason for moving to this position is that the pulley pressure supply oil passage 48 for supplying hydraulic pressure to the secondary pulley 30b fails (for example, the pressure reducing valve 49 is locked and the line pressure is generated, but the secondary pulley pressure P _sec This is because the torque capacity can be secured by the mechanical stoppers of the primary pulley and the secondary pulley and the belt slip can be prevented even if the pulley position is set to the minimum gear ratio side even when the state is low). . In general, the input torque that can be transmitted by the pulley increases as the gear ratio decreases.
[0068]
Incidentally, the pressure regulator valve 40 fails and the primary pulley pressure P _pri And secondary pulley pressure P _sec When both are low, even if the step motor 54 is moved to the overdrive side operation limit, the pulley ratio remains at the intermediate pulley position due to insufficient hydraulic pressure.
[0069]
At t3, since the actual position of the step motor 54 has reached the overdrive side operation limit, in the flowchart of FIG. 4, step S201 → step S202 → step S203 → step S204 → step S205 → step S206 → step S207 → step S209. It will be the flow to go.
[0070]
That is, it is determined in step S205 that the actual position of the step motor 54 has reached the overdrive side operation limit, and the timer is counted down in step S206. Subsequently, it is determined in step S207 that the countdown has not ended, and in step S209, a command for setting the torque limit amount of the engine 20 to 50 Nm is continuously output.
[0071]
This is the secondary pulley pressure P _sec This is because when the position of the step motor 54 does not reach the overdrive side operation limit, torque cannot be transmitted when the position of the step motor 54 does not reach the overdrive side operation limit. Further, as described above, when the pressure regulator valve 40 fails, the pulley ratio remains at the intermediate pulley position. Therefore, it is necessary to reduce the torque limit amount in order to suppress belt slip.
[0072]
At t4, since a predetermined time has elapsed since the actual position of the step motor 54 reached the overdrive side operation limit, in the flowchart of FIG. 4, step S201 → step S202 → step S203 → step S204 → step S205 → step S206 → step S207. → The flow proceeds to step S208.
[0073]
That is, it is determined in step S207 that the countdown has ended, and in step S208, a command for setting the torque limit amount of the engine 20 to 70 Nm is output to the ECU 19.
[0074]
Next, the effect will be described.
(1) Primary speed N _pri Has a maximum speed ratio 2.7 that can be taken by the mechanism, and the secondary rotational speed N _sec When the state where the value is equal to or greater than the value multiplied by the value continues for a predetermined time, it is determined that belt slip has occurred. Therefore, the maximum gear ratio is instantaneously determined by the detection error of the primary and secondary rotational speed sensors 4 and 5. It is possible to prevent erroneous determination of belt slipping when the value becomes unacceptable, and it is possible to improve belt slip determination accuracy.
[0075]
(2) When the engine speed Ne is 600 rpm or higher, that is, when it is estimated that a sufficient line pressure is generated, it is determined that belt slippage has occurred due to the above conditions, so that the hydraulic circuit has failed. For example, it is possible to reliably detect a belt slip due to a stick of an electrohydraulic control valve or the like in a short time from the occurrence, and the durability of the belt can be improved. On the other hand, when the engine speed Ne is less than 600 rpm, belt protection control is not performed excessively for belt slip that occurs when the engine rotation is unstable, and deterioration in running performance can be prevented.
[0076]
(3) When it is determined that belt slip has occurred, the engine speed Ne is limited to a predetermined value or less, the target position of the step motor 54 is set to the overdrive side operation limit, and the torque limit of the engine 20 is limited. In order to suppress the amount to 50 Nm, the pressure reducing valve 49 for supplying hydraulic pressure to the secondary pulley 30b is locked and the line pressure is generated, but the secondary pulley pressure P _sec Even in a low state, by setting the pulley position to the most overdrive side, torque capacity can be secured by the mechanical stoppers of the primary pulley and the secondary pulley, and belt slip can be prevented. Furthermore, even when the pressure regulator valve 40 fails and the pulley ratio remains at the intermediate pulley position due to insufficient hydraulic pressure, the belt slip can be prevented.
[0077]
(4) When it is determined that belt slip has occurred, the idle speed when the vehicle is stopped is increased, so that the amount of oil pump 8 is secured when the vehicle is stopped to prevent belt slip when starting. Can do.
[0078]
(5) Although it is possible to determine the belt slip on the condition that the difference between the target hydraulic pressure and the actual hydraulic pressure is large, the surface of the belt and the pulley deteriorates due to a change with time, and the friction coefficient μ decreases. If oil pressure is generated but the belt slips, belt slip cannot be detected. On the other hand, by detecting the belt slip by the method of the present embodiment, it is possible to reliably detect the belt slip even in the situation where the belt slip occurs despite the actual hydraulic pressure reaching the target hydraulic pressure. .
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration of a main unit of a vehicle including a belt-type continuously variable transmission according to an embodiment.
FIG. 2 is a circuit diagram showing a configuration of a hydraulic circuit in the embodiment.
FIG. 3 is a flowchart showing a flow of belt slip determination control processing in a CVT control unit.
FIG. 4 is a flowchart showing a flow of belt protection control processing at the time of belt slip determination in the CVT control unit.
FIG. 5 is a time chart showing a belt protection control action at the time of belt slip determination.
FIG. 6 is a map showing a predetermined time set according to acceleration.
[Explanation of symbols]
1 Torque converter
2 Lock-up clutch
3 Belt type continuously variable transmission
4 Primary speed sensor
5 Secondary rotational speed sensor
6 Hydraulic control valve unit
8 Oil pump
9 Control unit
10 Accelerator position sensor
11 Oil temperature sensor
12 Engine output shaft
13 Transmission input shaft
14 Primary pressure sensor
15 Secondary pressure sensor
16 Engine speed sensor
17 Throttle opening sensor
17a Follower wheel sensor
18 engine
19 Engine control unit (ECU)
20 Forward / reverse switching mechanism
31 Fixed conical plate
32 Movable conical plate
33 Primary pulley cylinder chamber
34 belt
35 Fixed conical plate
36 Movable conical plate
37 Secondary pulley cylinder chamber
38 Driven shaft
40 pressure regulator valve
41, 42, 43, 44, 46 Oilway
45 Orifice
49 Pressure reducing valve
50 Pilot valve
51 Oilway
60 Clutch regulator valve
61 Oilway
70 Select switching solenoid
71 Lock-up solenoid
72,73 Oilway
80 Select switching valve
81, 82, 83, 84 Oilway
90 Select control valve
91 Spool valve
92 Spring
93 Oilway
100 Manual valve
101 Oilway
102 Orifice

Claims (6)

A primary pulley with a variable pulley interval is provided on the main shaft on the engine side, a secondary pulley with a variable pulley interval is provided on the auxiliary shaft on the wheel side arranged in parallel with the main shaft, and a drive belt is wound between both pulleys, In a continuously variable transmission that continuously changes speed by controlling the hydraulic pressure of both pulleys and changing the ratio of the winding diameter of the drive belt to both pulleys,
Gear ratio calculating means for calculating a gear ratio based on the primary pulley rotation speed and the secondary pulley rotation speed;
Belt slip judging means for judging that belt slip has occurred when the value of the gear ratio is continuously deviated from the gear ratio area on the mechanism for a predetermined time;
Acceleration detecting means for detecting the acceleration of the vehicle;
Provided,
The control device for a belt type continuously variable transmission, wherein the belt slip determining means sets the predetermined time longer as the detected acceleration is larger . The control device for a belt-type continuously variable transmission according to claim 1,
A control device for a belt type continuously variable transmission , further comprising belt protection control means for performing belt protection control when it is determined by the belt slip determination means that belt slip has occurred . The control device for a belt-type continuously variable transmission according to claim 2 ,
The belt-type continuously variable transmission control device , wherein the belt protection control is control for restricting an upper limit of engine torque . The control device for a belt-type continuously variable transmission according to claim 2 ,
The belt-type continuously variable transmission control device , wherein the belt protection control is an upshift . The control device for a belt-type continuously variable transmission according to claim 2 ,
The belt-type continuously variable transmission control device according to claim 1, wherein the belt protection control is control for limiting an upper limit of an engine speed . The control device for a belt-type continuously variable transmission according to claim 2 ,
The belt-type continuously variable transmission control device according to claim 1, wherein the belt protection control is control for increasing an engine idle speed when the vehicle is stopped by a predetermined speed .

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