JP2009257489A - Controller for continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller for a continuously variable transmission capable of imparting appropriate clamping force in consideration of prevention of slipping and durability to a transmission belt when excessive torque caused by slipping of a driving wheel is input to the belt type continuously variable transmission. <P>SOLUTION: An ECU obtains an estimated vehicle speed V(B) and an actual vehicle speed V(A) (step S1). The ECU calculates a slip amount by obtaining a difference between the actual vehicle speed V(A) and the estimated vehicle speed V(B), and determines existence of the slip of the driving wheel by comparing the calculated slip amount and a reference value (step S2). When it is determined that the slip occurs (step S2; Yes), the ECU first increases belt clamping force by increasing a hydraulic pressure in accordance with a speed ratio of the belt type continuously variable transmission (step S3). Next, the ECU corrects the hydraulic pressure so as to increase the hydraulic pressure for the increase amount in accordance with the slip amount (step S4). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for a continuously variable transmission, and more particularly to a technique for controlling a clamping pressure applied to a transmission belt of a belt type continuously variable transmission.

  Conventionally, a continuously variable transmission in which a transmission belt is wound around a pair of pulleys having a variable groove width is known. In such a continuously variable transmission, a clamping pressure that prevents the transmission belt from slipping is applied to the transmission belt. However, when the vehicle travels on a slippery road surface, the drive wheels may slip on the road surface. In such a case, if the driving wheel grips again on the road surface due to an increase in the friction coefficient of the road surface or braking, the output rotational speed of the continuously variable transmission decreases rapidly. As a result, the torque transmitted to the transmission belt becomes excessive, and the transmission belt can slip. In order to prevent the transmission belt from slipping, there is a technique for increasing the clamping pressure applied to the transmission belt when slippage of the drive wheel is detected.

Japanese Patent Application Laid-Open No. 2004-116606 (Patent Document 1) discloses a control of a belt-type continuously variable transmission system for a vehicle that prevents belt slippage even when a drive wheel spins a wheel and further grips. An apparatus is disclosed. The control device described in this publication is wound around an input-side primary pulley whose groove width changes according to oil pressure, an output-side secondary pulley whose groove width changes according to oil pressure, and a primary pulley and a secondary pulley. And a belt-type continuously variable transmission system for a vehicle including a belt having a pulley contact radius changing. The control device includes wheel spin detection means for detecting wheel spin of the drive wheel, primary pressure adjustment means for adjusting the hydraulic pressure supplied to the primary pulley, secondary pressure adjustment means for adjusting the hydraulic pressure supplied to the secondary pulley, and the drive wheel And a control means for increasing the belt torque capacity by increasing and correcting the primary pressure and the secondary pressure when wheel spin is detected. Further, in the above publication, when the wheel spin of the driving wheel is detected, the maximum pulley supply pressure that can be generated is calculated from the oil temperature and the engine speed, and the pulley supply pressure is calculated as the primary pulley and the secondary pulley. It is disclosed that the primary pressure and the secondary pressure are corrected to be increased by supplying them to the main body.
JP 2004-116606 A JP-A-4-277363 Japanese Utility Model Publication No. 3-38517

  In order to ensure the reliability of the transmission belt for a long period of time, it is preferable that an excessive load is not applied to the transmission belt. However, according to Japanese Patent Application Laid-Open No. 2004-116606, when a drive wheel spin occurs, the maximum pulley supply pressure is supplied to the primary pulley and the secondary pulley regardless of the degree of the spin, and the belt is clamped. Increasing the pressure is disclosed. According to the technique disclosed in the above-mentioned document, there is a possibility that the durability of the belt is rapidly lowered.

  The present invention has been made in order to solve the above-described problems, and its purpose is to prevent slipping and to prevent slipping when excessive torque due to slipping of drive wheels is input to a belt-type continuously variable transmission. It is an object of the present invention to provide a control device for a continuously variable transmission capable of applying an appropriate clamping force in consideration of durability to a transmission belt.

  In summary, the present invention controls a continuously variable transmission that is mounted on a vehicle and has a pair of pulleys with variable groove widths and a transmission belt that is wound around the pair of pulleys and transmits power by frictional force. When the drive wheel of the vehicle slips, a slip detection unit for detecting the slip amount of the drive wheel, and control for increasing the clamping pressure of the transmission belt according to the slip amount detected by the slip detection unit A part.

  Preferably, the clamping pressure increases in accordance with an increase in hydraulic pressure supplied from the hydraulic circuit to the pair of pulleys. The control unit controls the hydraulic circuit so that the increase rate of the hydraulic pressure with respect to the slip amount increases as the slip amount increases.

  Preferably, the control device further includes a rotation speed change rate detection unit that detects a change rate of the rotation speed of the output shaft of the continuously variable transmission. When it is determined that the rotational speed has decreased based on the detected change rate, the control unit corrects the increase amount of the clamping pressure according to the decrease rate.

  Preferably, the clamping pressure increases in accordance with an increase in hydraulic pressure supplied from the hydraulic circuit to the pair of pulleys. The control unit controls the hydraulic circuit so that the rate of change of hydraulic pressure with respect to the absolute value increases as the absolute value of the decrease rate increases.

  According to the present invention, when excessive torque caused by slip of the drive wheels is input to the belt-type continuously variable transmission, slippage of the transmission belt can be suppressed and durability can be prevented from being lowered.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

[Embodiment 1]
A vehicle equipped with a control device according to a first embodiment of the present invention will be described with reference to FIG. The output of the engine 200 of the drive device 100 mounted on the vehicle is input to the belt type continuously variable transmission 500 via the torque converter 300 and the forward / reverse switching device 400. The output of the belt type continuously variable transmission 500 is transmitted to the reduction gear 600 and the differential gear device 700 and distributed to the left and right drive wheels 800. The driving device 100 is controlled by an ECU (Electronic Control Unit) 900 described later. The control device according to the present embodiment is realized, for example, when ECU 900 executes a program stored in ROM (Read Only Memory) 930 of ECU 900.

  The torque converter 300 includes a pump impeller 302 connected to the crankshaft of the engine 200 and a turbine impeller 306 connected to the forward / reverse switching device 400 via the turbine shaft 304. A lockup clutch 308 is provided between the pump impeller 302 and the turbine impeller 306. The lockup clutch 308 is engaged or released when the hydraulic pressure supply to the engagement side oil chamber and the release side oil chamber is switched.

  When the lockup clutch 308 is completely engaged, the pump impeller 302 and the turbine impeller 306 are integrally rotated. The pump impeller 302 includes a mechanical oil pump 310 that generates a hydraulic pressure for controlling the shift of the belt type continuously variable transmission 500, generating a belt clamping pressure, and supplying lubricating oil to each part. Is provided.

  The forward / reverse switching device 400 is composed of a double pinion type planetary gear device. Turbine shaft 304 of torque converter 300 is connected to sun gear 402. The input shaft 502 of the belt type continuously variable transmission 500 is connected to the carrier 404. Carrier 404 and sun gear 402 are connected via forward clutch 406. Ring gear 408 is fixed to the housing via reverse brake 410. The forward clutch 406 and the reverse brake 410 are frictionally engaged by a hydraulic cylinder. The input rotational speed of the forward clutch 406 is the same as the rotational speed of the turbine shaft 304, that is, the turbine rotational speed NT.

  When the forward clutch 406 is engaged and the reverse brake 410 is released, the forward / reverse switching device 400 enters the forward engagement state. In this state, the driving force in the forward direction is transmitted to the belt type continuously variable transmission 500. When the reverse brake 410 is engaged and the forward clutch 406 is released, the forward / reverse switching device 400 enters the reverse engagement state. In this state, the input shaft 502 is rotated in the reverse direction with respect to the turbine shaft 304. As a result, the driving force in the reverse direction is transmitted to the belt type continuously variable transmission 500. When both forward clutch 406 and reverse brake 410 are released, forward / reverse switching device 400 enters a neutral state in which power transmission is interrupted.

  The belt type continuously variable transmission 500 includes a primary pulley 504 provided on the input shaft 502, a secondary pulley 508 provided on the output shaft 506, and a transmission belt 510 wound around these pulleys. Power is transmitted using frictional forces between the pulleys and the transmission belt 510.

  Each pulley is composed of a hydraulic cylinder so that the groove width is variable. By controlling the hydraulic pressure of the hydraulic cylinder of the primary pulley 504, the groove width of each pulley changes. As a result, the engagement diameter of the transmission belt 510 is changed, and the gear ratio GR (= primary pulley rotation speed NIN / secondary pulley rotation speed NOUT) is continuously changed.

  As shown in FIG. 2, the ECU 900 includes an engine speed sensor 902, a turbine speed sensor 904, a vehicle speed sensor 906, a throttle opening sensor 908, a cooling water temperature sensor 910, an oil temperature sensor 912, an accelerator opening sensor 914, a foot A brake switch 916, a position sensor 918, a primary pulley rotation speed sensor 922, a secondary pulley rotation speed sensor 924, and a vehicle speed estimation unit 926 are connected.

  The engine speed sensor 902 detects the engine speed (engine speed) NE of the engine 200. The turbine rotation speed sensor 904 detects the rotation speed (turbine rotation speed) NT of the turbine shaft 304. The vehicle speed sensor 906 detects an actual vehicle speed V (A) that is an actual vehicle speed. Various methods can be used as the detection method of the actual vehicle speed V (A). As an example, a method of detecting the actual vehicle speed V (A) based on the turbine rotational speed NT can be employed.

  The throttle opening sensor 908 detects the opening degree θ (TH) of the electronic throttle valve. Cooling water temperature sensor 910 detects cooling water temperature T (W) of engine 200. The oil temperature sensor 912 detects the oil temperature T (C) of the belt type continuously variable transmission 500 or the like. The accelerator opening sensor 914 detects the accelerator pedal opening A (CC). The foot brake switch 916 detects whether or not the foot brake is operated. When the brake pedal is operated, the foot brake switch 916 is turned on. If the brake pedal is not operated, the foot brake switch 916 is turned off.

  The position sensor 918 detects the position P (SH) of the shift lever 920 by determining whether the contact provided at the position corresponding to the shift position is ON or OFF. Primary pulley rotation speed sensor 922 detects the rotation speed NIN of primary pulley 504. Secondary pulley rotation speed sensor 924 detects rotation speed NOUT of secondary pulley 508.

  Vehicle speed estimation unit 926 estimates the speed of the vehicle body, and outputs the estimated speed (estimated vehicle speed V (B)) to ECU 900. The vehicle speed estimation unit 926 estimates the speed of the vehicle body by the following method, for example. When the vehicle according to the present embodiment is a two-wheel drive vehicle (for example, an FF vehicle or an FR vehicle), vehicle speed estimation section 926 estimates the speed of the vehicle body from the rotational speed of the driven wheel. When the vehicle according to the present embodiment is a four-wheel drive vehicle, vehicle speed estimation section 926 estimates the speed of the vehicle body from the acceleration of the vehicle. Note that the method for estimating the speed of the vehicle body is not limited to these methods.

  A signal representing the detection result of each sensor is transmitted to ECU 900. The turbine rotational speed NT coincides with the primary pulley rotational speed NIN during forward traveling with the forward clutch 406 engaged. The actual vehicle speed V (A) is a value corresponding to the secondary pulley rotation speed NOUT. Therefore, when the vehicle is stopped and the forward clutch 406 is engaged, the turbine speed NT is zero.

  ECU 900 includes a CPU (Central Processing Unit), a memory, an input / output interface, and the like. The CPU performs signal processing according to a program stored in the memory. Thereby, output control of the engine 200, shift control of the belt-type continuously variable transmission 500, belt clamping pressure control, engagement / release control of the forward clutch 406, engagement / release control of the reverse brake 410, and the like are executed.

  Output control of the engine 200 is performed by an electronic throttle valve 1000, a fuel injection device 1100, an ignition device 1200, and the like. Shift control of belt type continuously variable transmission 500, belt clamping pressure control, engagement / release control of forward clutch 406, and engagement / release control of reverse brake 410 are performed by hydraulic control circuit 2000.

  A part of the hydraulic control circuit 2000 will be described with reference to FIG. FIG. 3 shows an example of the configuration of the hydraulic control circuit 2000, and the configuration of the hydraulic control circuit 2000 is not limited to the configuration shown in FIG.

  The hydraulic pressure generated by the oil pump 310 is supplied to the primary regulator valve 2100, the modulator valve (1) 2310 and the modulator valve (3) 2330 through the line pressure oil path 2002.

  The primary regulator valve 2100 is selectively supplied with control pressure from one of the SLT linear solenoid valve 2200 and the SLS linear solenoid valve 2210. In the present embodiment, both the SLT linear solenoid valve 2200 and the SLS linear solenoid valve 2210 are normally open solenoid valves (the hydraulic pressure output at the time of non-energization is maximized). Note that the SLT linear solenoid valve 2200 and the SLS linear solenoid valve 2210 may be normally closed (the hydraulic pressure output when not energized is minimized (“0”)).

  The spool of the primary regulator valve 2100 slides up and down according to the supplied control pressure. As a result, the hydraulic pressure generated by the oil pump 310 is regulated (adjusted) by the primary regulator valve 2100. The hydraulic pressure adjusted by primary regulator valve 2100 is used as line pressure PL. In the present embodiment, the higher the control pressure supplied to primary regulator valve 2100, the higher the line pressure PL. Note that the higher the control pressure supplied to the primary regulator valve 2100, the lower the line pressure PL may be.

  The SLT linear solenoid valve 2200 and the SLS linear solenoid valve 2210 are supplied with the hydraulic pressure regulated by the modulator valve (3) 2330 using the line pressure PL as a source pressure.

  SLT linear solenoid valve 2200 and SLS linear solenoid valve 2210 generate a control pressure in accordance with a current value determined by a duty signal transmitted from ECU 900.

  Of the control pressure (output hydraulic pressure) of the SLT linear solenoid valve 2200 and the control pressure (output hydraulic pressure) of the SLS linear solenoid valve 2210, the control pressure supplied to the primary regulator valve 2100 is selected by the control valve 2400.

  When the spool of the control valve 2400 is in the state (A) in FIG. 3 (left side state), the control pressure is supplied from the SLT linear solenoid valve 2200 to the primary regulator valve 2100. That is, the line pressure PL is controlled according to the control pressure of the SLT linear solenoid valve 2200.

  When the spool of the control valve 2400 is in the state (B) in FIG. 3 (right state), the control pressure is supplied from the SLS linear solenoid valve 2210 to the primary regulator valve 2100. That is, the line pressure PL is controlled according to the control pressure of the SLS linear solenoid valve 2210.

  When the spool of the control valve 2400 is in the state of (B) in FIG. 3, the control pressure of the SLT linear solenoid valve 2200 is supplied to a manual valve 2600 described later.

  The spool of the control valve 2400 is urged in one direction by a spring. Hydraulic pressure is supplied from the shift control duty solenoid (1) 2510 and the shift control duty solenoid (2) 2520 so as to oppose the urging force of the spring.

  When hydraulic pressure is supplied to the control valve 2400 from both the shift control duty solenoid (1) 2510 and the shift control duty solenoid (2) 2520, the spool of the control valve 2400 is in the state of (B) in FIG.

  When hydraulic pressure is not supplied to the control valve 2400 from at least one of the shift control duty solenoid (1) 2510 and the shift control duty solenoid (2) 2520, the spool of the control valve 2400 is driven by the biasing force of the spring. 3 is in the state (A).

  The hydraulic pressure adjusted by the modulator valve (4) 2340 is supplied to the shift control duty solenoid (1) 2510 and the shift control duty solenoid (2) 2520. The modulator valve (4) 2340 regulates the hydraulic pressure supplied from the modulator valve (3) 2330 to a constant pressure.

  The modulator valve (1) 2310 outputs a hydraulic pressure that is regulated using the line pressure PL as a source pressure. The hydraulic pressure output from the modulator valve (1) 2310 is supplied to the hydraulic cylinder of the secondary pulley 508. The hydraulic cylinder of the secondary pulley 508 is supplied with a hydraulic pressure that does not cause the transmission belt 510 to slip.

  The modulator valve (1) 2310 is provided with a spool that can move in the axial direction and a spring that biases the spool to one side. Modulator valve (1) 2310 regulates line pressure PL introduced to modulator valve (1) 2310 using the output hydraulic pressure of SLS linear solenoid valve 2210, which is duty controlled by ECU 900, as a pilot pressure. The hydraulic pressure adjusted by the modulator valve (3) is supplied to the hydraulic cylinder of the secondary pulley 508. The belt clamping pressure is increased or decreased according to the output hydraulic pressure from the modulator valve (1) 2310.

  The SLS linear solenoid valve 2210 is controlled so as to have a belt clamping pressure at which no belt slip occurs, according to a map using the speed ratio GR as a parameter and a map using the slip amount of the drive wheel as a parameter. Specifically, the excitation current for the SLS linear solenoid valve 2210 is controlled with a duty ratio corresponding to the belt clamping pressure. In the present embodiment, when the drive wheel slips, the belt clamping pressure is increased and corrected to suppress the subsequent belt slip due to a sudden change in the transmission torque caused by the drive wheel grip. The control of the belt clamping pressure in this case will be described later.

  The hydraulic pressure supplied to the hydraulic cylinder of the secondary pulley 508 is detected by the pressure sensor 2312.

  The manual valve 2600 will be described with reference to FIG. Manual valve 2600 is mechanically switched according to the operation of shift lever 920. Thereby, the forward clutch 406 and the reverse brake 410 are engaged or released.

  Shift lever 920 is operated to a “P” position for parking, an “R” position for reverse travel, an “N” position for interrupting power transmission, a “D” position and “B” position for forward travel.

  In the “P” position and the “N” position, the hydraulic pressure in the forward clutch 406 and the reverse brake 410 is drained from the manual valve 2600. Thereby, the forward clutch 406 and the reverse brake 410 are released.

  In the “R” position, hydraulic pressure is supplied from the manual valve 2600 to the reverse brake 410. Thereby, the reverse brake 410 is engaged. On the other hand, the hydraulic pressure in forward clutch 406 is drained from manual valve 2600. As a result, the forward clutch 406 is released.

  When the control valve 2400 is in the state (A) in FIG. 4 (left side state), the modulator pressure PM supplied from the modulator valve (2) (not shown) is supplied to the manual valve 2600 via the control valve 2400. . The reverse brake 410 is held in the engaged state by the modulator pressure PM.

  When the control valve 2400 is in the state (B) in FIG. 4 (right side state), the hydraulic pressure adjusted by the SLT linear solenoid valve 2200 is supplied to the manual valve 2600. By adjusting the hydraulic pressure by the SLT linear solenoid valve 2200, the reverse brake 410 is gently engaged, and a shock at the time of engagement is suppressed.

  In the “D” position and the “B” position, hydraulic pressure is supplied from the manual valve 2600 to the forward clutch 406. As a result, the forward clutch 406 is engaged. On the other hand, the hydraulic pressure in the reverse brake 410 is drained from the manual valve 2600. Thereby, the reverse brake 410 is released.

  When the control valve 2400 is in the state (A) in FIG. 4 (left side state), the modulator pressure PM supplied from the modulator valve (2) (not shown) is supplied to the manual valve 2600 via the control valve 2400. . The forward clutch 406 is held in the engaged state by the modulator pressure PM.

  When the control valve 2400 is in the state (B) in FIG. 4 (right side state), the hydraulic pressure adjusted by the SLT linear solenoid valve 2200 is supplied to the manual valve 2600. By adjusting the hydraulic pressure by the SLT linear solenoid valve 2200, the forward clutch 406 is gently engaged, and a shock at the time of engagement is suppressed.

  The SLT linear solenoid valve 2200 normally controls the line pressure PL via the control valve 2400. The SLS linear solenoid valve 2210 normally controls the belt clamping pressure via the modulator valve (1) 2310.

  On the other hand, when the neutral control execution condition including the condition that the vehicle stops (the vehicle speed becomes “0”) with the shift lever 920 in the “D” position is satisfied, the SLT linear solenoid valve 2200 The engagement force of the forward clutch 406 is controlled so that the engagement force of 406 decreases. The SLS linear solenoid valve 2210 controls the belt clamping pressure via the modulator valve (1) 2310, and controls the line pressure PL instead of the SLT linear solenoid valve 2200.

  When a garage shift is performed in which the shift lever 920 is operated from the “N” position to the “D” position or the “R” position, the forward clutch 406 or the reverse brake 410 is gently engaged with the SLT linear solenoid valve 2200. Thus, the engagement force of the forward clutch 406 or the reverse brake 410 is controlled. The SLS linear solenoid valve 2210 controls the belt clamping pressure via the modulator valve (1) 2310, and controls the line pressure PL instead of the SLT linear solenoid valve 2200.

  With reference to FIG. 5, a configuration for performing the shift control will be described. Shift control is performed by controlling the supply and discharge of hydraulic pressure to and from the hydraulic cylinder of the primary pulley 504. Supply and discharge of hydraulic fluid to and from the hydraulic cylinder of the primary pulley 504 is performed using a ratio control valve (1) 2710 and a ratio control valve (2) 2720.

  The hydraulic cylinder of the primary pulley 504 is in communication with a ratio control valve (1) 2710 to which the line pressure PL is supplied and a ratio control valve (2) 2720 connected to the drain.

  The ratio control valve (1) 2710 is a valve for executing an upshift. The ratio control valve (1) 2710 is configured to open and close the flow path between the input port to which the line pressure PL is supplied and the output port connected to the hydraulic cylinder of the primary pulley 504 with a spool.

  A spring is disposed at one end of the spool of the ratio control valve (1) 2710. A port to which the control pressure from the shift control duty solenoid (1) 2510 is supplied is formed at the end opposite to the spring across the spool. Further, a port to which a control pressure is supplied from the shift control duty solenoid (2) 2520 is formed at the end on the side where the spring is disposed.

  When the control pressure from the shift control duty solenoid (1) 2510 is increased and the control pressure is not output from the shift control duty solenoid (2) 2520, the spool of the ratio control valve (1) 2710 in FIG. (D) state (right side state).

  In this state, the hydraulic pressure supplied to the hydraulic cylinder of the primary pulley 504 increases and the groove width of the primary pulley 504 becomes narrower. As a result, the gear ratio decreases. That is, an upshift is performed. Further, by increasing the supply flow rate of hydraulic oil at that time, the speed change speed is increased.

  The ratio control valve (2) 2720 is a valve for executing a downshift. A spring is disposed at one end of the spool of the ratio control valve (2) 2720. A port to which the control pressure from the shift control duty solenoid (1) 2510 is supplied is formed at the end on the side where the spring is disposed. A port to which the control pressure from the shift control duty solenoid (2) 2520 is supplied is formed at the end opposite to the spring across the spool.

  When the control pressure from the shift control duty solenoid (2) 2520 is increased and the control pressure is not output from the shift control duty solenoid (1) 2510, the spool of the ratio control valve (2) 2720 in FIG. The state (C) (the state on the left side) is reached. At the same time, the spool of the ratio control valve (1) 2710 is in the state (C) (left side state) in FIG.

  In this state, the hydraulic oil is discharged from the hydraulic cylinder of the primary pulley 504 via the ratio control valve (1) 2710 and the ratio control valve (2) 2720. Therefore, the groove width of the primary pulley 504 is widened. As a result, the gear ratio increases. That is, downshift. Further, by increasing the discharge flow rate of the hydraulic oil at that time, the speed change speed is increased.

  With reference to FIG. 6, the function of ECU 900 which is the control apparatus according to the present embodiment will be described. Note that the functions described below may be realized by hardware or software.

  ECU 900 includes a slip detection unit 940, a clamping pressure increase unit 950, and a map storage unit 960.

  The slip detection unit 940 detects that the drive wheel 800 shown in FIG. 1 is slipping and the slip amount of the drive wheel 800 based on the actual vehicle speed V (A) and the estimated vehicle speed V (B).

  When the slip detection unit 940 detects that the driving wheel 800 is slipping, the clamping pressure increasing unit 950 is configured to have a belt clamping force higher than a normal value determined as the belt clamping pressure when the driving wheel 800 is not slipping. The SLS linear solenoid valve 2210 is controlled so that the pressure value increases. Further, the clamping pressure increasing unit 950 increases the belt clamping pressure according to the slip amount of the drive wheel 800 detected by the slip detection unit 940.

  The map storage unit 960 stores a map that defines the relationship between the slip amount and the increase amount of the output hydraulic pressure of the SLS linear solenoid valve 2210 (hereinafter simply referred to as “hydraulic pressure”). This map is obtained in advance by experiments, for example.

  An example of a map stored in the map storage unit 960 will be described with reference to FIG. In this map, the hydraulic pressure correction amount (increase amount) increases as the slip amount increases. In this map, the slip amount and the increase amount of the hydraulic pressure are proportional.

  Returning to FIG. 6, the clamping pressure increasing unit 950 calculates the amount of increase in hydraulic pressure based on the slip amount detected by the slip detection unit 940 and the map stored in the map storage unit 960. Then, the clamping pressure increasing unit 950 controls the SLS linear solenoid valve 2210 so that the control pressure increases by the increase amount. As a result, the belt clamping pressure increases according to the slip amount detected by the slip detection unit 940.

  In order to calculate the gear ratio of the belt type continuously variable transmission 500, the rotational speed NIN of the primary pulley 504 and the rotational speed NOUT of the secondary pulley 508 are input to the clamping pressure increasing unit 950.

  With reference to FIG. 8 and FIG. 6, a control structure of a program executed by ECU 900 which is the control device according to the present embodiment will be described. The process shown in the flowchart of FIG. 8 is called from the main routine and executed at a predetermined cycle, for example.

  In step S <b> 1, the slip detection unit 940 acquires the actual vehicle speed V (A) from the vehicle speed sensor 906 and acquires the estimated vehicle speed V (B) from the vehicle speed estimation unit 926.

  In step S2, ECU 900 calculates a slip amount, and determines whether or not a drive wheel slip has occurred based on the calculated slip amount. Specifically, the slip detection unit 940 calculates a difference between the estimated vehicle speed V (B) and the actual vehicle speed V (A). This difference is the slip amount. When the calculated slip amount is larger than the reference value of the slip amount, the clamping pressure increasing unit 950 determines that the drive wheel slip has occurred. If drive wheel slip has occurred (YES in step S2), the process proceeds to S3. If drive wheel slip has not occurred (NO in step S2), the process returns to the main routine.

  In step S3, the clamping pressure increasing unit 950 increases the hydraulic pressure by an increase amount corresponding to the transmission gear ratio GR (= primary pulley rotation speed NIN / secondary pulley rotation speed NOUT).

  In step S4, the clamping pressure increasing unit 950 corrects the hydraulic pressure according to the slip amount calculated in step S2. Specifically, the clamping pressure increasing unit 950 calculates an increase amount of the hydraulic pressure based on the map shown in FIG. 7 and the slip amount calculated in step S2, and increases the hydraulic pressure by the increase amount. When the process of step S4 ends, the entire process is returned to the main routine.

  An operation of ECU 900 that is the control device according to the present embodiment based on the above-described structure and flowchart will be described.

  The ECU 900 acquires the estimated vehicle speed V (B) estimated by the vehicle speed estimation unit 926 and the actual vehicle speed V (A) detected by the vehicle speed sensor 906 (step S1). The ECU 900 calculates the slip amount by obtaining the difference between the actual vehicle speed V (A) and the estimated vehicle speed V (B), and compares the calculated slip amount with a reference value to determine the presence or absence of slippage of the drive wheels. (Step S2). If it is determined that slip has occurred (YES in step S2), the belt clamping pressure is increased (steps S3 and S4). On the other hand, when it is determined that no slip has occurred (NO in step S2), the belt clamping pressure is maintained as it is.

  ECU 900 first increases the belt clamping pressure by increasing the hydraulic pressure in accordance with the gear ratio of belt type continuously variable transmission 500 (step S3). For example, it is assumed that the driving wheel slips when the vehicle travels, and then the driving wheel grips the road surface again. In such a case, the rotational speed of the output shaft of the belt type continuously variable transmission 500 suddenly increases and then rapidly decreases. As a result, a large torque is shockedly input to the belt type continuously variable transmission 500. This input torque becomes a disturbance for the control of the belt clamping pressure.

  The larger the gear ratio, the greater the input torque of the belt type continuously variable transmission 500. Accordingly, when slipping and gripping of the driving wheel occurs, the torque that is shockedly input as a disturbance also increases. In order to prevent belt slip due to this disturbance, the ECU 900 increases the hydraulic pressure in accordance with the gear ratio of the belt type continuously variable transmission 500 (step S3).

  However, in order to prevent belt slip, it is necessary to increase the belt clamping pressure. However, if the clamping pressure is excessively increased, the load on the belt increases. In order to ensure the reliability of the belt over a long period of time, it is necessary to prevent the belt durability from being deteriorated early.

  Therefore, the ECU 900 corrects the hydraulic pressure so that the hydraulic pressure increases by an increase amount corresponding to the slip amount (step S4). As a result, the belt clamping pressure is increased by an increase amount corresponding to the slip amount. Therefore, the belt clamping pressure in consideration of the magnitude of torque that is shockedly input to the belt type continuously variable transmission 500 by the slip and grip of the drive wheel. Can be applied to the transmission belt. Therefore, according to the first embodiment, not only can the transmission belt slip, but also excessive belt clamping pressure can be prevented from being applied to the transmission belt.

[Embodiment 2]
Hereinafter, a second embodiment of the present invention will be described. The present embodiment is the first implementation described above in that the hydraulic pressure increased according to the slip amount is further corrected (increased) based on the decrease rate of the output shaft rotational speed of the transmission of the continuously variable transmission. It is different from the form.

  The configuration of the vehicle according to the second embodiment and the configuration of the hydraulic control circuit mounted on the vehicle are the same as those of the first embodiment, and the functions thereof are also the same. Therefore, detailed description thereof will not be repeated hereinafter.

  As shown in FIG. 9, when the drive wheel slips, the output shaft rotational speed (turbine rotational speed NT) of the belt-type continuously variable transmission temporarily increases rapidly. In the description of the first embodiment, it has been shown that the output shaft rotational speed once suddenly increased due to the grip of the driving wheel rapidly decreases. Even when the driver operates the foot brake as well as the grip of the drive wheel, the rotation speed of the drive wheel decreases, so the output shaft rotation speed decreases.

  The slope of the straight line indicated by the broken line in FIG. 9 indicates the rate of decrease in the output shaft rotational speed. Hereinafter, the absolute value of the decrease rate is indicated as | ΔNT |. | ΔNT | corresponds to the absolute value of the slope of the straight line.

  When | ΔNT | is large, the torque that is shockedly input to the belt type continuously variable transmission 500 also increases. For example, it is considered that | ΔNT | increases as the braking performance of the vehicle improves. When this input torque becomes excessive, the transmission belt can slip due to inertia. Therefore, in the second embodiment, a process of correcting (further increasing) the hydraulic pressure increased according to the slip amount according to | ΔNT |.

  With reference to FIG. 10, the function of ECU 900 which is the control device according to the present embodiment will be described. Note that the functions described below may be realized by hardware or software.

  ECU 900 includes a slip detection unit 940, a clamping pressure increase unit 950, a map storage unit 960, and a change rate calculation unit 970.

  The slip detection unit 940 detects that the drive wheel 800 shown in FIG. 1 is slipping and the slip amount of the drive wheel 800 based on the actual vehicle speed V (A) and the estimated vehicle speed V (B).

  The change rate calculation unit 970 acquires the turbine rotation speed NT from the turbine rotation speed sensor 904 (not shown) at a constant time interval (for example, 1 second). Hereinafter, the turbine rotational speed NT (the output shaft rotational speed of the belt-type continuously variable transmission 500) is referred to as “output shaft rotational speed”. The change rate calculation unit 970 calculates | ΔNT |, which is the absolute value of the decrease rate of the output shaft rotational speed, based on the acquired output shaft rotational speed.

  The map storage unit 960 stores the map shown in FIG. Further, the map storage unit 960 stores a map that associates | ΔNT | with the hydraulic pressure correction amount. Referring to FIG. 11, in this map, the hydraulic pressure correction amount increases as | ΔNT | increases. That is, in this map, the correction amount of the hydraulic pressure is determined so that the clamping pressure of the transmission belt increases as | ΔNT | increases. In this map, | ΔNT | is proportional to the hydraulic pressure correction amount. Similarly to the map shown in FIG. 7, the map shown in FIG.

  Returning to FIG. 10, when the slip detection unit 940 detects that the drive wheel 800 is slipping, the clamping pressure increasing unit 950 controls the SLS linear solenoid valve 2210 to perform the same control as in the first embodiment. In contrast, the value of the belt clamping pressure is increased. Further, when it is determined that the hydraulic pressure needs to be corrected based on | ΔNT | calculated by the change rate calculation unit 970, the clamping pressure increasing unit 950 stores the calculated | ΔNT | in the map storage unit 960. The value of the belt clamping pressure is increased by correcting the hydraulic pressure based on the map (see FIG. 11).

  With reference to FIG. 12 and FIG. 10, a control structure of a program executed by ECU 900 which is the control device according to the present embodiment will be described. The process shown in the flowchart of FIG. 12 is called and executed from the main routine at a predetermined cycle, for example.

  Further, the process shown in the flowchart of FIG. 12 is different from the process shown in the flowchart of FIG. 8 in that steps S5 and S6 are added. The process of steps S1 to S4 in the flowchart of FIG. 12 is the same as the process of the corresponding step of FIG. Therefore, in the following, the processes of steps S5 and S6 will be described, and the description of the processes of other steps will not be repeated.

  In step S5, change rate calculation unit 970 calculates | ΔNT |, which is an absolute value of the decrease rate of the output shaft rotation speed. When the calculated | ΔNT | is larger than the reference value of the decrease rate of the output shaft rotational speed, the clamping pressure increasing unit 950 determines that the decrease of the output shaft rotational speed is large. In this case (YES in step S5), the process proceeds to step S6. On the other hand, when it is determined that the decrease in the output shaft speed is small (NO in step S5), the entire process returns to the main routine.

  In step S6, the clamping pressure increasing unit 950 calculates a correction amount (increase amount) of the hydraulic pressure based on | ΔNT | calculated in step S5 and the map shown in FIG. Only increase. When the process of step S6 ends, the entire process is returned to the main routine.

  An operation of ECU 900 that is the control device according to the present embodiment based on the above-described structure and flowchart will be described. Since operations corresponding to steps S1 to S4 are the same as those in the first embodiment, description thereof will not be repeated below, and operations corresponding to steps S5 and S6 will be described.

  When the drive wheel slips, the output shaft rotational speed of the belt type continuously variable transmission 500 suddenly increases, but the rotational speed rapidly decreases due to the foot brake operation by the driver. ECU 900 calculates the absolute value of the change rate of the output shaft rotational speed and compares the calculated value (| ΔNT |) with a reference value to determine whether or not the output shaft rotational speed has changed ( Step S5). As the absolute value of the rate of change in the rotational speed increases, the torque that is shockedly input to the belt-type continuously variable transmission 500 increases, so even if the hydraulic pressure is increased by an increase amount corresponding to the slip amount, Slip may occur. Therefore, when the decrease in output shaft speed is large (YES in step S5), ECU 900 executes hydraulic pressure correction according to | ΔNT |, which is the absolute value of the decrease rate (step S6). As a result, as in the first embodiment, a belt clamping pressure reflecting the magnitude of torque that is shockedly input to the belt type continuously variable transmission 500 can be applied to the transmission belt. Therefore, slippage of the transmission belt can be prevented. If the decrease in the output shaft rotational speed is small (NO in step S5), the hydraulic pressure increases by an increase amount corresponding to the slip amount as in the first embodiment.

  According to the second embodiment, the transmission belt can be prevented from slipping as described above. Further, according to the second embodiment, since the correction amount (increase amount) of the hydraulic pressure is determined based on the slip amount and | ΔNT |, it is possible to prevent an excessive belt clamping pressure from being applied to the transmission belt. it can. Therefore, according to the second embodiment, similarly to the first embodiment, it is possible not only to prevent the transmission belt from slipping but also to prevent an excessive belt clamping pressure from being applied to the transmission belt. Can do.

  In addition, the correction | amendment which further increases the increase amount calculated based on the slip amount was demonstrated about the correction | amendment of the hydraulic pressure in this embodiment. However, the correction of the hydraulic pressure in this embodiment is not limited to this, and the correction amount calculated based on | ΔNT | may be subtracted from the increase amount calculated based on the slip amount. Even with such correction, it is possible to achieve both prevention of slippage of the transmission belt and prevention of application of excessive belt clamping pressure to the transmission belt.

<Modification of Second Embodiment>
In this modification, the map stored in the map storage unit 960 shown in FIG. 10 is different from the maps shown in FIGS. Since the other points of this modification are the same as those of the second embodiment described above, description thereof will not be repeated.

  FIG. 13 is a diagram showing a map that defines the relationship between the slip amount and the hydraulic pressure increase amount, which is applied to the modification of the second embodiment of the present invention. Referring to FIG. 13, in the map according to this modification, the change rate (increase rate) of the hydraulic pressure increase amount with respect to the slip amount increases as the slip amount increases. On the other hand, in the map shown in FIG. 7, the rate of change of the hydraulic pressure increase amount with respect to the slip amount is constant. In this respect, the map shown in FIG. 13 is different from the map shown in FIG.

  FIG. 14 is a diagram showing a map that defines the relationship between the absolute value of the reduction amount of the output shaft rotation speed and the hydraulic pressure correction amount, which is applied to the modification of the second embodiment of the present invention. Referring to FIG. 14, in the map according to this modification, the change rate (increase rate) of the hydraulic pressure increase amount with respect to | ΔNT | increases as the absolute value (| ΔNT |) of the decrease amount of the output shaft rotation speed increases. . On the other hand, in the map shown in FIG. 11, the rate of change of the hydraulic pressure correction amount with respect to | ΔNT | is constant. In this respect, the map shown in FIG. 14 is different from the map shown in FIG.

  As the gear ratio of the continuously variable transmission increases, the input torque also increases. Therefore, it is considered that the slip amount increases when the drive wheels slip once. As a result, it is considered that the torque that is shockedly input to the continuously variable transmission by the slip and grip of the drive wheels also increases. Therefore, as shown in the map of FIG. 13, by increasing the rate of change of the hydraulic pressure with respect to the slip amount as the slip amount increases, in a region where the slip amount is large, a larger belt clamping pressure can be applied to the transmission belt, In a region where the slip amount is small, a smaller belt clamping pressure can be applied to the transmission belt. Accordingly, it is possible to prevent the belt from slipping and to prevent an excessive clamping pressure from being applied to the belt.

  Similarly, the greater the absolute value of the rate of decrease in the output shaft rotation speed, the greater the torque (disturbance input) that is input to the continuously variable transmission. Therefore, as shown in FIG. 14, the larger the | ΔNT | is, the larger the rate of change of the hydraulic pressure with respect to | ΔNT | is, so that in a region where | ΔNT | is large (region where the disturbance input is large), a larger belt clamping pressure. Can be applied to the transmission belt, and in a region where | ΔNT | is large (region where the disturbance input is small), a smaller belt clamping pressure can be applied to the transmission belt. Accordingly, it is possible to prevent the belt from slipping and to prevent an excessive clamping pressure from being applied to the belt.

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

1 is a skeleton diagram of a vehicle equipped with an ECU that is a control device according to a first embodiment of the present invention. It is a control block diagram which shows ECU which is a control apparatus which concerns on the 1st Embodiment of this invention. It is a 1st figure which shows a hydraulic control circuit. It is a 2nd figure which shows a hydraulic control circuit. It is a 3rd figure which shows a hydraulic control circuit. It is a functional block diagram of ECU which is a control device concerning a 1st embodiment of the present invention. It is a figure which shows the 1st map memorize | stored in the map memory | storage part 960. FIG. It is a flowchart which shows the control structure of the program which ECU which is a control apparatus which concerns on the 1st Embodiment of this invention performs. It is a figure which shows the change of the output shaft rotational speed of a continuously variable transmission. It is a functional block diagram of ECU which is a control apparatus which concerns on the 2nd Embodiment of this invention. It is a figure which shows the 2nd map memorize | stored in the map memory | storage part 960. FIG. It is a flowchart which shows the control structure of the program which ECU which is a control apparatus which concerns on the 2nd Embodiment of this invention performs. It is a figure which shows the map which defined the relationship between the slip amount and the hydraulic pressure increase amount applied to the modification of the 2nd Embodiment of this invention. It is a figure which shows the map which defined the relationship between the absolute value of the fall amount of output-shaft rotation speed, and a hydraulic pressure correction amount applied to the modification of the 2nd Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 Drive device, 200 Engine, 300 Torque converter, 302 Pump impeller, 304 Turbine shaft, 306 Turbine impeller, 308 Lock-up clutch, 310 Oil pump, 400 Forward / reverse switching device, 402 Sun gear, 404 carrier, 406 Forward clutch, 408 ring gear, 410 reverse brake, 500 belt type continuously variable transmission, 502 input shaft, 504 primary pulley, 506 output shaft, 508 secondary pulley, 510 transmission belt, 600 reduction gear, 700 differential gear device, 800 drive wheel, 902 Engine speed sensor, 904 Turbine speed sensor, 906 Vehicle speed sensor, 908 Throttle opening sensor, 910 Cooling water temperature sensor, 912 Oil temperature sensor, 914 Accelerator opening sensor, 916 Foot brake switch, 918 position sensor, 920 shift lever, 922 primary pulley rotation speed sensor, 924 secondary pulley rotation speed sensor, 926 vehicle speed estimation section, 940 slip detection section, 950 clamping pressure increase section, 960 map storage section, 970 rate of change Calculation unit, 1000 electronic throttle valve, 1100 fuel injection device, 1200 ignition device, 2000 hydraulic control circuit, 2002 line pressure oil passage, 2100 primary regulator valve, 2200 linear solenoid valve, 2210 linear solenoid valve, 2312 pressure sensor, 2400 control valve 2600 Manual valve.

Claims (4)

A control device that controls a continuously variable transmission that is mounted on a vehicle and has a pair of pulleys having variable groove widths and a transmission belt that is wound around the pair of pulleys and transmits power by frictional force.
A slip detector for detecting a slip amount of the drive wheel when the drive wheel of the vehicle slips;
A control device for a continuously variable transmission, comprising: a control unit that increases a clamping pressure of the transmission belt in accordance with the slip amount detected by the slip detection unit. The clamping pressure increases according to an increase in hydraulic pressure supplied from the hydraulic circuit to the pair of pulleys,
2. The continuously variable transmission control device according to claim 1, wherein the control unit controls the hydraulic circuit such that an increase rate of the hydraulic pressure with respect to the slip amount increases as the slip amount increases. The controller is
A rotation speed change rate detection unit for detecting a change rate of the rotation speed of the output shaft of the continuously variable transmission;
The said control part correct | amends the said increase amount of the said clamping pressure according to the said decreasing rate, when it determines with the said rotation speed falling based on the detected said changing rate. Control device for continuously variable transmission. The clamping pressure increases according to an increase in hydraulic pressure supplied from the hydraulic circuit to the pair of pulleys,
4. The continuously variable transmission control device according to claim 3, wherein the control unit controls the hydraulic circuit so that the rate of change of the hydraulic pressure with respect to the absolute value increases as the absolute value of the decrease rate increases. 5. .

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