JP2010265918A - Device and method for controlling continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suitably prevent the slip of a belt by improving responsiveness during an increase of secondary pressure in a belt type continuously variable transmission. <P>SOLUTION: An SVR is mechanically switched to a Pi select state setting line pressure PL in a value depending on primary pressure Pin when the primary pressure Pin is larger than secondary pressure Pout, and mechanically switched to a Pout select state setting the PL in a value depending on the Pout when the Pout is larger than the Pin. An ECU calculates target secondary pressure Pt required for suppressing belt slippage (S102) when it is estimated that there is a possibility of generating the belt slippage (S100; Yes), and increases the Pin to increase the PL to be the Pt or higher and increases the Pout to the Pt with the PL increased to be the Pt or higher as original pressure (S108) when the SRV is in the Pin select state and it is determined that the Pout cannot be increased to the Pt at the present PL (S106; Yes). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to control of a continuously variable transmission, and more particularly to control for preventing belt slippage in a belt type continuously variable transmission.

  A continuously variable transmission including a drive pulley, a driven pulley, and a belt wound around these pulleys is already known and put into practical use. Such a belt type continuously variable transmission has a hydraulic actuator that controls the pulley width on the drive side and a hydraulic actuator that controls the pulley width on the driven side, and controls the hydraulic pressure supplied to both hydraulic actuators. By changing the pulley width, the gear ratio is changed steplessly.

  As an apparatus for controlling the hydraulic pressure supplied to such a hydraulic actuator, for example, there is a hydraulic control apparatus disclosed in Japanese Patent Laid-Open No. 11-247981 (Patent Document 1). A hydraulic control device disclosed in Japanese Patent Application Laid-Open No. 11-247981 includes a drive-side pulley and a driven-side pulley, a belt wound around both pulleys, a drive-side cylinder chamber and a driven-side cylinder chamber that control both pulley widths. And the first regulator valve and the second regulator valve are used to set the line pressure that is the source pressure of the control hydraulic pressure supplied to each cylinder chamber, and the first control hydraulic pressure supplied to the drive side cylinder chamber is the first linear solenoid valve. And the second control hydraulic pressure to be supplied to the driven cylinder chamber is set by the second linear solenoid valve. In addition, the first and second regulator valves regulate the line pressure using a control back pressure that is a high pressure of the first and second control back pressures set by the first and second linear solenoid valves. . Specifically, the second regulator valve selects and outputs the first control back pressure to the first regulator valve when the first control back pressure is higher than the first control back pressure. In addition, when the second control back pressure is higher, the second control back pressure is selected and mechanically switched to a state of outputting to the second regulator valve. The first regulator valve is configured to regulate the line pressure according to the control back pressure input from the second regulator valve.

Japanese Patent Laid-Open No. 11-247981

  Incidentally, in the hydraulic control device disclosed in Japanese Patent Application Laid-Open No. 11-247981, for example, when the second regulator valve is in a state of outputting the first control back pressure, the line pressure becomes a value dependent on the first control hydraulic pressure. . In this state, in order to increase the second control hydraulic pressure on the driven side from the line pressure depending on the first control hydraulic pressure in order to prevent belt slip, the second regulator valve is changed from the state in which the first control back pressure is output to the second control hydraulic pressure. A method of increasing the second control back pressure so that the second control hydraulic pressure becomes a necessary pressure after switching the state to output the two control back pressure and setting the line pressure to a value dependent on the second control hydraulic pressure is conceivable. .

  However, in this method, the response time is delayed by the time required to switch the state of the second regulator valve, so the second control hydraulic pressure on the driven side cannot be increased early, and belt slipping is prevented appropriately. I am concerned that I cannot do it.

  The present invention has been made to solve the above-described problems, and its object is to improve the response when the hydraulic pressure of the driven pulley is increased in a belt-type continuously variable transmission. It is an object of the present invention to provide a control device and a control method that can appropriately prevent belt slippage.

  A control device according to a first aspect of the present invention is a continuously variable transmission for a vehicle that includes a first pulley on a drive side, a second pulley on a driven side, and a belt wound around the first pulley and the second pulley. It is a control device. The vehicle includes a first valve that regulates the first pressure supplied to the first pulley, a second valve that regulates the second pressure supplied to the second pulley, and control source pressures of the first pressure and the second pressure. A hydraulic circuit having a third valve for controlling the line pressure. The third valve mechanically switches to a first state where the line pressure is set to the first line pressure depending on the first pressure in a range where the first pressure is greater than the second pressure, and the second pressure is the first pressure. In a larger range, the line pressure is mechanically switched to a second state in which the line pressure is set to a second line pressure depending on the second pressure. The control device includes a prediction unit that predicts slipping of the belt based on the state of the vehicle, and a control unit that controls the first valve and the second valve. When the prediction unit predicts that the belt slips, the control unit increases the first line pressure while maintaining the third valve in the first state when the third valve is in the first state. The first valve and the second valve are controlled to increase the first pressure and increase the second pressure using the increased first line pressure as a source pressure.

  In the control device according to the second invention, the control unit calculates a target value of the second pressure that can prevent the belt from slipping based on the state of the vehicle when the prediction unit predicts that the belt slips. When the third valve is in the first state and the first line pressure is smaller than the target value of the second pressure, the first pressure is increased so that the first line pressure increases above the target value of the second pressure. And the second pressure is increased to the target value of the second pressure.

  In the control device according to the third aspect of the present invention, when the prediction unit does not predict that the belt slips, the control unit causes the first pressure and the second pressure when the speed ratio of the continuously variable transmission is a predetermined speed ratio. The normal control for controlling the first valve and the second valve is executed such that the first pressure is decreased and the second pressure is increased as the transmission ratio is made to coincide with the pressure. The control device further includes a storage unit that stores a map in which a correspondence relationship between the speed ratio and the first line pressure during normal control is determined in a range where the speed ratio is smaller than the reference speed ratio corresponding to the predetermined speed ratio. When the predicting unit predicts that the belt slips, the control unit calculates a first speed ratio when the first line pressure becomes the target value of the second pressure with reference to the map, and When the actual speed ratio is included between the first speed ratio and the reference speed ratio, it is determined that the third valve is in the first state and the first line pressure is smaller than the target value of the second pressure.

  In the control device according to the fourth aspect of the present invention, when the prediction unit does not predict that the belt will slip, the control unit causes the first pressure and the second pressure when the speed ratio of the continuously variable transmission is the predetermined speed ratio. The normal control for controlling the first valve and the second valve is executed such that the first pressure is decreased and the second pressure is increased as the transmission ratio is made to coincide with the pressure. The control device further includes an input unit to which a detected value of the first pressure by the hydraulic sensor is input, and a storage unit that stores a reference speed ratio corresponding to the predetermined speed ratio. When the predicting unit predicts that the belt slips, the control unit determines that the actual transmission ratio of the continuously variable transmission is smaller than the reference transmission ratio and the detected value of the first pressure is lower than the target value of the second pressure. When it is small, it is determined that the third valve is in the first state and the first line pressure is smaller than the target value of the second pressure.

  In the control device according to the fifth aspect of the present invention, when the predicting unit predicts that the belt slips, the control unit is in the first state and the target value of the second pressure is higher than the first line pressure. Is smaller or when the third valve is in the second state, the second pressure is increased to the target value of the second pressure without increasing the first pressure.

  A control method according to a sixth aspect of the invention is a continuously variable transmission for a vehicle including a first pulley on a drive side, a second pulley on a driven side, and a belt wound around the first pulley and the second pulley. This is a control method performed by the control device. The vehicle includes a first valve that regulates the first pressure supplied to the first pulley, a second valve that regulates the second pressure supplied to the second pulley, and control source pressures of the first pressure and the second pressure. A hydraulic circuit having a third valve for controlling the line pressure. The third valve mechanically switches to a first state where the line pressure is set to the first line pressure depending on the first pressure in a range where the first pressure is greater than the second pressure, and the second pressure is the first pressure. In a larger range, the line pressure is mechanically switched to a second state in which the line pressure is set to a second line pressure depending on the second pressure. The control method includes a step of predicting belt slip based on a state of the vehicle, and a step of controlling the first valve and the second valve. The step of controlling the first valve and the second valve maintains the third valve in the first state when the third valve is in the first state when it is predicted that the belt slips in the predicting step. While controlling the first valve and the second valve to increase the first pressure so as to increase the first line pressure, and to increase the second pressure using the increased first line pressure as a source pressure including.

  According to the present invention, when the slip of the belt is predicted, when the third valve is in the first state, the third valve is maintained in the first state instead of switching the third valve to the second state. However, the first line pressure is increased, and the second pressure is increased using the increased first line pressure as a source pressure. Therefore, compared with the case where the 3rd valve is switched to the 2nd state, the responsiveness of the 2nd pressure can be improved and belt slip can be prevented appropriately.

It is a figure which shows the power train of a vehicle. It is a control block diagram of a vehicle. It is a figure which shows a hydraulic control circuit. It is a figure which shows the detail of a select reducing valve. It is a figure which shows the map which defined the correspondence of a gear ratio, a primary pressure, a secondary pressure, and a line pressure. It is a functional block diagram of ECU. It is a flowchart (the 1) which shows the flow of a process of ECU. It is a figure for demonstrating a part of process of ECU. It is a flowchart (the 2) which shows the flow of a process of ECU.

  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.

<First Embodiment>
FIG. 1 is a diagram showing a power train 100 of a vehicle according to the present embodiment. The output of the engine 200 of the power train 100 is input to the continuously variable transmission 500 via the torque converter 300 and the forward / reverse switching device 400. The output of the 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 power train 100 is controlled by an ECU (Electronic Control Unit) 900 described later.

  The torque converter 300 includes a pump impeller 302 connected to the crankshaft of the engine 200 and a turbine runner 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 runner 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 runner 306 are rotated together. On the pump impeller 302 side of the torque converter 300, a machine that generates a hydraulic pressure for controlling the transmission of the continuously variable transmission 500, generating a belt clamping pressure, and supplying hydraulic oil for lubrication to each part. An oil pump 310 of the type 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 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 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 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 continuously variable transmission 500 includes a drive-side primary pulley 504 provided on the input shaft 502, a driven-side secondary pulley 508 provided on the output shaft 506, and a metal belt 530 wound around these pulleys. It consists of. Power transmission is performed using frictional force between each pulley and the belt 530.

  The primary pulley 504 includes a primary sheave 510 that is a movable sheave and a fixed sheave 512 so that the groove width is variable. Similarly, the secondary pulley 508 includes a secondary sheave 520 that is a movable sheave and a fixed sheave 522 so that the groove width is variable.

  By controlling the hydraulic pressure supplied to the primary hydraulic chamber 514 (hereinafter referred to as “primary pressure Pin”), the groove width of the primary pulley 504 changes. Along with this, the groove width of the secondary pulley 508 also changes. Thereby, the effective diameter of the belt 530 is changed, and the gear ratio γ (= primary pulley rotational speed Nin / secondary pulley rotational speed Nout) is continuously changed.

  Further, by controlling the hydraulic pressure supplied to the secondary hydraulic chamber 524 (hereinafter referred to as “secondary pressure Pout”), the clamping pressure of the belt 530 (the force with which the secondary pulley 508 clamps the belt 530) is controlled.

  FIG. 2 is a control block diagram of a vehicle including ECU 900 that is a control device according to the present embodiment. 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 position sensor 908, a coolant temperature sensor 910, an oil temperature sensor 912, an accelerator pedal position sensor 914, a brake pedaling force. A sensor 916, a position sensor 918, a primary pulley rotational speed sensor 922, a secondary pulley rotational speed sensor 924, and a G sensor 926 are connected.

  The engine rotation speed sensor 902 detects the rotation speed (engine rotation 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 the vehicle speed. The throttle position sensor 908 detects the position THA of the electronic throttle valve. Cooling water temperature sensor 910 detects cooling water temperature TW of engine 200. The oil temperature sensor 912 detects the temperature of hydraulic oil (hereinafter also referred to as oil temperature) THO used for the operation of the continuously variable transmission 500. The accelerator pedal position sensor 914 detects the accelerator pedal position ACC. The brake pedal force sensor 916 detects a brake pedal force (a force with which the driver steps on the brake pedal). The position sensor 918 detects the position PSH of the shift lever 920 operated by the driver. The primary pulley rotation speed sensor 922 detects the rotation speed (input shaft rotation speed) Nin of the primary pulley 504. The secondary pulley rotational speed sensor 924 detects the rotational speed (output shaft rotational speed) Nout of the secondary pulley 508. The G sensor 926 detects the vehicle longitudinal acceleration acting on the vehicle. Each of these sensors transmits a signal representing the detection result to ECU 900.

  ECU 900 performs output control of engine 200, shift control of continuously variable transmission 500, belt clamping pressure control, forward clutch 406 engagement / release control, reverse brake 410 engagement / release control, and the like.

  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. The hydraulic control circuit 2000 performs the shift control of the continuously variable transmission 500, the belt clamping pressure control, the engagement / release control of the forward clutch 406, and the engagement / release control of the reverse brake 410.

  The main part of the hydraulic control circuit 2000 will be described with reference to FIGS. The hydraulic control circuit 2000 described below is an example, and the present invention is not limited to this.

  The hydraulic control circuit 2000 includes an oil pump 2011, a regulator valve 2012, a modulator valve 2013, a first solenoid valve 2014, a second solenoid valve 2015, a primary pressure adjustment valve 2016, a secondary pressure adjustment valve 2017, and a select reducing valve ( Select Reducing Valve (hereinafter referred to as “SRV”) 2018.

  The oil pump 2011 outputs the hydraulic oil input via the oil strainer 2010 for removing impurities to the regulator valve 2012 side. The hydraulic pressure output from the oil pump 2011 is regulated to a line pressure PL that is a control source pressure of the primary pressure Pin and the secondary pressure Pout by the regulator valve 2012 and the SRV 2018. The modulator valve 2013 reduces the line pressure PL to produce a constant modulator pressure PM.

  The modulator pressure PM is supplied to the first solenoid valve 2014 and the second solenoid valve 2015. The first solenoid valve 2014 and the second solenoid valve 2015 regulate the modulator pressure PM by controlling the energization amount of the built-in linear solenoid by the ECU 900, and respectively adjust the first solenoid pressure Pslp and the second solenoid pressure Psls. Output.

  The first solenoid pressure Pslp is sent to the primary pressure adjustment valve 2016. The primary pressure adjustment valve 2016 adjusts the line pressure PL according to the first solenoid pressure Pslp, generates the primary pressure Pin, and supplies it to the primary hydraulic chamber 514.

  The relationship between the first solenoid pressure Pslp and the primary pressure Pin is as shown in Expression (1).

Pin = η × Pslp + β1 (1)
Here, η indicates the gain of the primary pressure Pin with respect to the first solenoid pressure Pslp in the primary pressure adjustment valve 2016, and β1 indicates a constant. The values of the gain η and the constant β1 are determined by the mechanical configuration and dimensions of the primary pressure adjustment valve 2016 and the spring load.

  On the other hand, the second solenoid pressure Psls is sent to the secondary pressure adjustment valve 2017. The secondary pressure adjustment valve 2017 adjusts the line pressure PL according to the second solenoid pressure Psls, generates the secondary pressure Pout, and supplies it to the secondary hydraulic chamber 524.

  The relationship between the second solenoid pressure Psls and the secondary pressure Pout is as shown in Expression (2).

Pout = α × Psls + β2 (2)
Here, α represents the gain of the secondary pressure Pout with respect to the second solenoid pressure Psls in the secondary pressure adjustment valve 2017, and β2 represents a constant. These gain α and constant β2 are determined by the mechanical configuration and dimensions of the secondary pressure adjusting valve 2017, and the spring load. Note that β2 is set to a minute value with respect to Pout.

  The hydraulic control circuit 2000 continuously controls the primary pressure Pin and the secondary pressure Pout by energization control of the first solenoid valve 2014 and the second solenoid valve 2015 by the ECU 900 to variably set the groove width of each pulley. Shift control of the transmission 500 is performed.

  The SRV 2018 is supplied with the modulator pressure PM, the primary pressure Pin, and the second solenoid pressure Psls. The SRV 2018 regulates the modulator pressure PM according to the relationship between the primary pressure Pin and the second solenoid pressure Psls, and generates the line pressure control oil pressure Psrv. The line pressure control hydraulic pressure Psrv is sent to the regulator valve 2012.

  The regulator valve 2012 sets the line pressure PL to a value corresponding to the higher one of the primary pressure Pin and the secondary pressure Pout according to the line pressure control oil pressure Psrv sent from the SRV 2018.

  FIG. 4 is a diagram showing details of the SRV 2018. As shown in FIG. 4, the SRV 2018 is provided with four first to fourth ports 2020, 2021, 2022, and 2023. The primary port Pin is input to the first port 2020, the second solenoid pressure Psls is input to the second port 2021, and the modulator pressure PM is input to the third port 2022. The fourth port 2023 is connected to the regulator valve 2012, and the line pressure control hydraulic pressure Psrv is output to the regulator valve 2012 through the fourth port 2023. The line pressure control hydraulic pressure Psrv is also fed back to the SRV 2018 as the back pressure of the SRV 2018.

  Inside the SRV 2018, there are provided a first spool 2024 and a second spool 2025 that are installed independently to be movable in the vertical direction in the drawing.

  The first spool 2024 is urged upward in the figure by the spring 2026 and is pressed downward in the figure by the second solenoid pressure Psls introduced into the second port 2021.

  On the other hand, the second spool 2025 is pressed upward in the figure by the second solenoid pressure Psls introduced into the second port 2021, and pressed downward in the figure by the primary pressure Pin introduced into the first port 2020. It is like that.

  In the second spool 2025, the downward pressing force in the figure due to the action of the primary pressure Pin is larger than the upward pressing force in the figure due to the action of the second solenoid pressure Psls (that is, Pin / α> Psls). ), The second spool 2025 moves downward in the figure, and the SRV 2018 is in the state shown in FIG. On the other hand, in the second spool 2025, the downward pressing force in the figure due to the action of the primary pressure Pin is smaller than the upward pressing force in the figure due to the action of the second solenoid pressure Psls (that is, Pin / α <Psls). ), The second spool 2025 moves upward in the figure, and the SRV 2018 is in the state shown in FIG. Here, α is an area ratio (α = Asls / Ain) of the plunger area Asls of the portion where the second solenoid pressure Psls acts on the plunger area Ain of the portion where the primary pressure Pin acts on the second spool 2025. In the present embodiment, the area ratio α is set to the same value as the gain α of the secondary pressure Pout described above.

  “Pin / α> Psls” is equivalent to “Pin> Pout−β2”. However, as described above, β2 is a slight value with respect to Pout. The case of Pout ”can be considered. Therefore, the SRV 2018 is generally in the state shown in FIG. 4A in the range of Pin> Pout, and in the range of Pin <Pout, in the state shown in FIG. 4B. Note that Pin and Pout may be directly input to the SRV 2018 to switch to the state shown in FIG. 4A when Pin> Pout and to the state shown in FIG. 4B when Pin <Pout.

  When the SRV 2018 is in the state shown in FIG. 4A, the line pressure control hydraulic pressure Psrv output from the SRV 2018 is expressed by Expression (3). On the other hand, when the SRV 2018 is in the state shown in FIG. 4B, the line pressure control hydraulic pressure Psrv is expressed by the equation (4).

Psrv = Pin / α−ΔP (3)
Psrv = Psls−ΔP (4)
When both “Pin / α” and “Psls” are smaller than “ΔP”, the spools 2024 and 2025 both move upward in the figure, and the line pressure control hydraulic pressure Psrv becomes zero.

In summary, the line pressure control oil pressure Psrv is as shown in the equation (5).
Psrv = MAX (0, MAX (Pin / α, Psls) −ΔP) (5)
The line pressure control oil pressure Psrv is input to the regulator valve 2012. The regulator valve 2012 adjusts the line pressure PL according to the line pressure control oil pressure Psrv. The line pressure PL and the line pressure control oil pressure Psrv have the relationship of Expression (6).

PL = α × Psrv + β (6)
Here, α is a gain of the line pressure PL with respect to the line pressure control hydraulic pressure Psrv in the regulator valve 2012, and β is a constant. The values of the gain α and the constant β are determined by the mechanical configuration and dimensions of the regulator valve 2012 and the spring load. The gain α of the line pressure PL is set to the same value as the area ratio α and the gain α of the secondary pressure Pout described above.

As described above, when Pin / α> Psls, the SRV 2018 is in the state shown in FIG. 4A, and Psrv = Pin / α−ΔP. Therefore, using equation (6),
PL = Pin + predetermined value D (where predetermined value D = β−αΔP) (7)
It can be seen that it is.

On the other hand, as described above, when Pin / α <Psls, SRV2018 is in the state shown in FIG. 4B, and Psrv = Psls−ΔP. Therefore, using Equation (2) and Equation (6),
PL = Pout + predetermined value C (predetermined value C = β−αΔP−β2) (8)
It can be seen that it is.

  Further, when the value of the line pressure control oil pressure Psrv when the line pressure PL becomes the allowable minimum value PLmin is set to a predetermined value δ, the regulator valve 2012 has a line pressure regardless of the line pressure control oil pressure Psrv when Psrv <δ. PL is set to the allowable minimum value PLmin.

  In summary, the line pressure PL output from the regulator valve 2012 is as shown in Expression (9).

PL = MAX {PLmin, MAX (Pout + C, Pin + D)} (9)
Therefore, when the SRV 2018 is in the state shown in FIG. 4A, the line pressure PL is set to a value dependent on the primary pressure Pin (a value higher than the primary pressure Pin by a predetermined value D). On the other hand, when the SRV 2018 is in the state shown in FIG. 4B, the line pressure PL is set to a value depending on the secondary pressure Pout (a value higher than the secondary pressure Pout by a predetermined value C). Accordingly, in the following description, the state shown in FIG. 4A in the SRV 2018 is also referred to as “Pin select state”, and the state shown in FIG. 4B is also referred to as “Pout select state”.

  With reference to FIG. 5, the relationship between the gear ratio γ, the primary pressure Pin, the secondary pressure Pout, and the line pressure PL during normal control will be described. FIG. 5 shows a γ-Pin map showing the correspondence between the gear ratio γ and the primary pressure Pin, a γ-Pout map showing the correspondence between the gear ratio γ and the secondary pressure Pout, and the gear ratio γ and line during normal control. The γ-PL map showing the correspondence with the pressure PL is shown. As shown in FIG. 5, the speed ratio γ varies in a range between a minimum value (maximum speed increase value) γmin and a maximum value (maximum deceleration speed value) γmax. Further, the γ-Pin map and the γ-Pout map intersect at a predetermined speed ratio γ0 in the change range (γmin to γmax) of the speed ratio γ.

  The ECU 900 sets a target speed ratio γt according to the running state of the vehicle during normal control, and the primary pressure Pin and the secondary pressure Pout have values shown in the map of FIG. 5 with respect to the target speed ratio γt. As described above, control signals are output to the first solenoid valve 2014 and the second solenoid valve 2015.

  That is, as shown in FIG. 5, ECU 900 decreases primary pressure Pin as the target speed ratio γt increases, and decreases the winding radius of belt 530 in primary pulley 504. On the other hand, the ECU 900 increases the belt pressure by the secondary pulley 508 by increasing the secondary pressure Pout as the target speed ratio γt increases. As a result, the actual speed ratio γ is controlled to the target speed ratio γt, and belt slippage is prevented.

  In this normal control, as shown in FIG. 5, when the gear ratio γ <the reference gear ratio γ2, the SRV 2018 is in the “Pin select state” and the line pressure PL = Pin + D. On the other hand, when the gear ratio γ> the reference gear ratio γ2, the SRV 2018 is in the “Pout selected state”, and the line pressure PL = Pout + C. Note that the reference speed ratio γ2 is a speed ratio corresponding to the predetermined speed ratio γ0, and is a speed ratio when Pin = Pout is substantially satisfied during normal control (specifically, when Pin = Pout−β2).

  Thus, during normal control, when the gear ratio γ <the reference gear ratio γ2, the primary pressure Pin> the secondary pressure Pout, and the SRV 2018 is mechanically switched to the “Pin select state”. On the other hand, when the gear ratio γ> the reference gear ratio γ2, the primary pressure Pin <the secondary pressure Pout, and the SRV 2018 is mechanically switched to the “Pout select state”.

  Thereby, it is possible to set the line pressure PL as low as possible while securing the necessary primary pressure Pin and secondary pressure Pout. Therefore, it is possible to improve the fuel consumption by suppressing the loss of the oil pump 310 while appropriately performing the shift control and the belt clamping pressure control.

  By the way, when the SRV 2018 is in the Pin select state, if it is necessary to increase the secondary pressure Pout to a value larger than the line pressure PL (= Pin + D) in order to prevent belt slip, the normal pressure Pin is set in the normal control. It is necessary to switch the state of the SRV 2018 from the Pin select state to the Pout select state by decreasing and increasing the secondary pressure Pout to satisfy Pin <Pout.

  However, in this method, the responsiveness is delayed by the time required for switching the state of the SRV 2018. Therefore, the line pressure PL and the secondary pressure Pout cannot be increased at an early stage during sudden braking, etc. There is a concern that it cannot be prevented properly.

  The most characteristic point of the present invention is that, in order to solve the above-described problem, when the ECU 900 needs to increase the secondary pressure Pout above the line pressure PL when the SRV 2018 is in the Pin selected state, Is to increase the secondary pressure Pout to the required pressure while maintaining the state of the SRV 2018 in the Pin selected state by performing different controls.

  FIG. 6 shows a functional block diagram of ECU 900. The ECU 900 stores an input interface 940 that receives information from each sensor and the like, and various information, programs, threshold values, maps, and the like, and reads and stores data from the arithmetic processing unit 950 as necessary. It includes a storage unit 960, an arithmetic processing unit 950 that performs arithmetic processing based on information from the input interface 940 and the storage unit 960, and an output interface 970 that outputs the processing result of the arithmetic processing unit 950 to each device.

  The storage unit 960 stores in advance the three maps shown in FIG. 5 described above, that is, the γ-Pin map, the γ-Pout map, and the γ-PL map during normal control.

  As described above, in the γ-Pin map and the γ-Pout map, Pin and Pout coincide when the speed ratio γ is the predetermined speed ratio γ0, and Pin> Pout in the range of γ <γ0. In the range of> γ0, Pin <Pout. Further, the γ-PL map shows the correspondence between the gear ratio γ and the line pressure PL = Pin + D in the range where the gear ratio γ is smaller than the reference gear ratio γ2 corresponding to the predetermined gear ratio γ0, rather than the reference gear ratio γ2. In the range where the gear ratio γ is large, the correspondence relationship between the gear ratio γ and the line pressure PL = Pout + C is determined in advance.

  The arithmetic processing unit 950 includes a prediction unit 951, a first control unit 952, and a second control unit 953.

  The predicting unit 951 predicts whether or not belt slip may occur in the normal control based on the state of the vehicle. For example, the predicting unit 951 predicts that belt slip may occur when the amount of change in the brake pedal force per unit time exceeds a threshold (during sudden braking). For example, when the fluctuation amount of the secondary pulley rotation speed Nout per unit time exceeds a threshold value due to disturbance or the like, or the fluctuation amount of the detection value of the G sensor 926 per unit time exceeds the threshold value. In some cases, it may be predicted that belt slip may occur.

  The first control unit 952 performs the above-described normal control when it is predicted that there is no possibility of belt slippage even in the normal control. That is, the first control unit 952 sets the target speed ratio γt according to the traveling state of the vehicle, and the primary pressure Pin and the secondary pressure Pout become values shown in the map of FIG. 5 with respect to the target speed ratio γt. As described above, control signals are output to the first solenoid valve 2014 and the second solenoid valve 2015.

  The second control unit 953 executes temporary control different from the normal control when it is predicted that belt slip may occur in the normal control. This temporary control is realized by a target pressure calculation unit 954, a determination unit 955, a Pin increase unit 956, and a Pout increase unit 957.

  The target pressure calculation unit 954 calculates, as the target secondary pressure Pt, a secondary pressure necessary for suppressing belt slip based on the running state of the vehicle. For example, the target pressure calculation unit 954 is based on the engine rotation speed NE, the primary pulley rotation speed Nin, the secondary pulley rotation speed Nout, the brake pedal force fluctuation amount, the G sensor value fluctuation amount, and the like. The target secondary pressure Pt is calculated based on the estimated input torque.

  Determination unit 955 determines whether SRV 2018 is in the Pin selected state and current line pressure PL is smaller than target secondary pressure Pt.

  The Pin increasing unit 956 reduces the primary pressure Pin so that the line pressure PL is equal to or higher than the target secondary pressure Pt when the SRV 2018 is in the Pin selected state and the current line pressure PL is smaller than the target secondary pressure Pt. A control signal is output to the first solenoid valve 2014 so as to increase it.

  The Pout increasing unit 957 outputs a control signal to the second solenoid valve 2015 so as to increase the secondary pressure Pout to the target secondary pressure Pt. In the case where the Pin increase unit 956 increases the primary pressure Pin, if the increase rate of the secondary pressure Pout is made larger than the increase rate of the primary pressure Pin, Pin <Pout is satisfied, and the state of the SRV 2018 is contrary to the intention. There is concern about switching to a state. Therefore, the Pout increasing unit 957 increases the secondary pressure Pout at a speed or timing at which at least the relationship of Pin> Pout is maintained.

  The functions described above may be realized by software or hardware.

  FIG. 7 is a flowchart showing a processing flow of ECU 900 when the above-described functions are realized by software. This process is repeatedly performed at a predetermined cycle time.

  As shown in FIG. 7, at step (hereinafter, step is abbreviated as S) 100, ECU 900 predicts whether or not there is a possibility of belt slippage by the above-described method. If a positive determination is made in this process (YES in S100), the process proceeds to S102. Otherwise (NO in S100), this process ends and the above-described normal control is performed.

  In S102, ECU 900 calculates target secondary pressure Pt (secondary pressure necessary for suppressing belt slip) by the above-described method.

  In S104, ECU 900 refers to the γ-PL map stored in storage unit 960, and calculates gear ratio γ1 at which the gear ratio is smaller than reference gear ratio γ2 and line pressure PL becomes target secondary pressure Pt. . As shown in FIG. 8, ECU 900 uses the γ-PL map to calculate the gear ratio when the gear ratio is smaller than the reference gear ratio γ2 and the line pressure PL becomes the target secondary pressure Pt. The ratio is set to the transmission ratio γ1.

  In S106, ECU 900 calculates current speed ratio γ (= Nin / Nout), and determines whether current speed ratio γ is included between γ1 and reference speed ratio γ2. This process is a process for determining whether or not the current state of the SRV 2018 is the Pin selected state and the current line pressure PL cannot increase the secondary pressure Pout to the target secondary pressure Pt.

  If the current speed ratio γ is included between γ1 and the reference speed ratio γ2 (YES in S106), ECU 900 determines that SRV2018 is in the Pin selected state and uses secondary pressure Pout as target secondary pressure at current line pressure PL. It is determined that the state cannot be increased to Pt, and the process proceeds to S108.

  On the other hand, when current speed ratio γ is smaller than γ1 (NO in S106), ECU 900 sets secondary pressure Pout as target secondary pressure at current line pressure PL without switching SRV2018, although SRV2018 is in the Pin selected state. It is determined that the pressure Pt can be increased, and the process proceeds to S110.

  ECU 900 increases secondary pressure Pout to target secondary pressure Pt without switching SRV2018 state when SRV2018 is in the Pout selected state when current speed ratio γ is larger than reference speed ratio γ2 (NO in S106). The process proceeds to S110.

  In S108, ECU 900 increases primary pressure Pin so that line pressure PL increases to or above target secondary pressure Pt, and increases secondary pressure Pout to target secondary pressure Pt. At this time, as described above, ECU 900 increases secondary pressure Pout at a speed or timing at which at least the relationship of Pin> Pout−β2 is maintained (that is, SRV2018 is maintained in the Pin selected state). By executing this process, the primary pressure Pin and the secondary pressure Pout are temporarily separated from the γ-Pin line and the γ-Pout line shown in FIG.

  In S110, ECU 900 increases secondary pressure Pout to target secondary pressure Pt without increasing primary pressure Pin. Note that the secondary pressure Pout is also controlled to a value temporarily separated from the γ-Pout line shown in FIG. 5 by executing this process.

  In S112, ECU 900 determines whether or not a predetermined return condition is satisfied. For example, when the fluctuation amount of the brake pedal force per unit time, the fluctuation amount of the secondary pulley rotation speed Nout, and the fluctuation amount of the G sensor value are smaller than the threshold values, the belt slips even if the normal control is performed. It is determined that there is no possibility, and it is determined that the return condition is satisfied. If a positive determination is made in this process (YES in S112), the process proceeds to S114. Otherwise (NO in S112), the process returns to S102.

  In S114, ECU 900 stops the temporary processing in S108 or S110 and returns the normal control.

  As described above, when ECU 900 according to the present embodiment predicts that belt slip may occur in normal control (YES in S100), target secondary pressure Pt necessary for suppressing belt slip is set. The gear ratio γ1 is calculated based on the target secondary pressure Pt and the γ-PL map shown in FIG. 5 (S102).

  Then, when the current gear ratio γ is included between γ1 and the reference gear ratio γ2, the ECU 900 increases the secondary pressure Pout to the target secondary pressure Pt when the SRV 2018 is in the Pin selected state and the current line pressure PL. It is determined that this is not possible (YES in S106).

  When this determination is made, the ECU 900 increases the primary pressure Pin so that the line pressure PL increases to the target secondary pressure Pt or higher without switching the state of the SRV 2018, and the line increased to the target secondary pressure Pt or higher. The secondary pressure Pout is increased to the target secondary pressure Pt using the pressure PL as a source pressure (S108).

  Thereby, the secondary pressure Pout can be increased to the target secondary pressure Pt while the state of the SRV 2018 is maintained in the Pin select state. Therefore, the control response of the secondary pressure Pout can be improved and the secondary pressure Pout can be increased at an early stage as compared with the case where the state of the SRV 2018 is switched to the Pout select state, and belt slip can be appropriately prevented.

<Second Embodiment>
Hereinafter, a second embodiment of the present invention will be described. In the first embodiment described above, the ECU 900 calculates γ1, and when γ1 <γ <γ2, the target state is the secondary pressure Pout when the current state of the SRV 2018 is the Pin selected state and the current line pressure PL. It was determined that the secondary pressure Pt cannot be increased (YES in S104 and S106 in FIG. 7).

  In contrast, in the present embodiment, a hydraulic sensor (not shown) that directly detects the primary pressure Pin is provided in the primary hydraulic chamber 514 and the like, and a detected value of the primary pressure Pin by the hydraulic sensor is input to the input interface 940. Let When the ECU 900 satisfies γ <γ2 and the detected value of the primary pressure Pin is smaller than the target secondary pressure Pt, the target state of the secondary pressure Pout is set when the current state of the SRV 2018 is the Pin selected state and the current line pressure PL. It is determined that the secondary pressure Pt cannot be increased. Since other structures, functions, and processes are the same as those in the first embodiment, detailed description thereof will not be repeated here.

  FIG. 9 is a flowchart showing a processing flow of ECU 900 according to the present embodiment. In the flowchart shown in FIG. 9, the same steps as those in the flowchart shown in FIG. The processing is the same for them. Therefore, detailed description thereof will not be repeated here.

  In S200, ECU 900 detects primary pressure Pin. In step S202, the ECU 900 calculates the current speed ratio γ, the current speed ratio γ is smaller than the reference speed ratio γ2 (see FIG. 5), and the detected value of the primary pressure Pin is smaller than the target secondary pressure Pt. Determine whether or not. When the current gear ratio γ is smaller than the reference gear ratio γ2 and the detected value of the primary pressure Pin is smaller than the target secondary pressure Pt, the ECU 900 determines that the SRV 2018 is in the Pin selected state and the secondary pressure is the current line pressure PL. It is determined that Pout cannot be increased to the target secondary pressure Pt, and the process proceeds to S108.

  When the current gear ratio γ is larger than the reference gear ratio γ2 and the detected value of the primary pressure Pin is smaller than the target secondary pressure Pt, the ECU 900 determines that the SRV 2018 is in the Pin selected state and the current line pressure PL is the secondary pressure. It is determined that Pout cannot be increased to the target secondary pressure Pt, and the process proceeds to S108.

  On the other hand, when the current gear ratio γ is smaller than the reference gear ratio γ2 but the detected value of the primary pressure Pin is larger than the target secondary pressure Pt (NO in S202), the ECU 900 is in the Pin select state. Determines that the secondary pressure Pout can be increased to the target secondary pressure Pt at the current line pressure PL without switching the state of the SRV 2018, and the process proceeds to S110.

  ECU 900 increases secondary pressure Pout to target secondary pressure Pt without switching SRV2018 state when SRV2018 is in the Pout selected state when current speed ratio γ is larger than reference speed ratio γ2 (NO in S106). The process proceeds to S110.

  Thus, in the present embodiment, a hydraulic pressure sensor that directly detects the primary pressure Pin is provided, and the secondary pressure is detected at the current line pressure PL based on the comparison result between the detected value of the primary pressure Pin and the target secondary pressure Pt. It can be determined whether or not Pout cannot be increased to the target secondary pressure Pt. Therefore, without calculating the gear ratio γ1, the secondary pressure Pout is increased to the target secondary pressure Pt at an early stage without switching the state of the SRV 2018, as in the first embodiment. It can be prevented appropriately.

  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.

  100 power train, 200 engine, 300 torque converter, 302 pump impeller, 304 turbine shaft, 306 turbine runner, 308 lockup clutch, 310 oil pump, 400 forward / reverse switching device, 402 sun gear, 404 carrier, 406 forward clutch, 408 ring gear , 410 reverse brake, 500 continuously variable transmission, 502 input shaft, 504 primary pulley, 506 output shaft, 508 secondary pulley, 510 primary sheave, 512 fixed sheave, 514 primary hydraulic chamber, 520 secondary sheave, 522 fixed sheave, 524 secondary Hydraulic chamber, 530 belt, 600 reduction gear, 700 differential gear device, 800 drive wheel, 900 ECU, 902 engine rotation speed center , 904 Turbine rotational speed sensor, 906 Vehicle speed sensor, 908 Throttle position sensor, 910 Cooling water temperature sensor, 912 Oil temperature sensor, 914 Accelerator pedal position sensor, 916 Brake pedal force sensor, 918 Position sensor, 920 Shift lever, 922 Primary pulley rotational speed Sensor, 924 Secondary pulley rotational speed sensor, 926 G sensor, 940 input interface, 950 arithmetic processing unit, 951 prediction unit, 952 first control unit, 953 second control unit, 954 target pressure calculation unit, 955 judgment unit, 956 Pin Increase unit, 957 Pout increase unit, 960 storage unit, 970 output interface, 1000 electronic throttle valve, 1100 fuel injection device, 1200 ignition device, 2000 hydraulic control circuit, 2010 Oil strainer, 2011 Oil pump, 2012 Regulator valve, 2013 Modulator valve, 2014 Solenoid valve, 2015 Solenoid valve, 2016 Primary pressure adjustment valve, 2017 Secondary pressure adjustment valve, 2020 First port, 2021 Second port, 2022 Third port , 2023 4th port, 2024 1st spool, 2025 2nd spool, 2026 Spring.

Claims (6)

A control device for a continuously variable transmission for a vehicle comprising a first pulley on a drive side, a second pulley on a driven side, and a belt wound around the first pulley and the second pulley,
The vehicle includes a first valve that regulates a first pressure supplied to the first pulley, a second valve that regulates a second pressure supplied to the second pulley, the first pressure, and the second pressure. A hydraulic circuit having a third valve for controlling the line pressure, which is a control pressure of the pressure,
The third valve is mechanically switched to a first state in which the line pressure is set to a first line pressure depending on the first pressure in a range where the first pressure is greater than the second pressure, In a range where two pressures are greater than the first pressure, the line pressure is mechanically switched to a second state in which the line pressure is set to a second line pressure depending on the second pressure.
The control device includes:
A predicting unit that predicts slipping of the belt based on the state of the vehicle;
A control unit for controlling the first valve and the second valve,
When the predicting unit predicts that the belt slips, and the third valve is in the first state, the control unit maintains the third valve in the first state while maintaining the third valve. The first valve and the second valve are controlled to increase the first pressure so as to increase one line pressure, and to increase the second pressure using the increased first line pressure as a source pressure. , Control device for continuously variable transmission.   The control unit calculates a target value of the second pressure that can prevent the belt from slipping based on a state of the vehicle when the prediction unit predicts that the belt will slip. When the valve is in the first state and the first line pressure is smaller than the target value of the second pressure, the first pressure is increased so that the first line pressure increases to a value equal to or higher than the target value of the second pressure. The control device for the continuously variable transmission according to claim 1, wherein the second pressure is increased to a target value of the second pressure. The control unit matches the first pressure and the second pressure when the gear ratio of the continuously variable transmission is a predetermined gear ratio when the prediction unit does not predict that the belt will slip. And performing normal control for controlling the first valve and the second valve so that the first pressure is decreased and the second pressure is increased as the speed ratio is larger,
The control device stores a map in which a correspondence relationship between the speed ratio and the first line pressure in the normal control is determined in a range where the speed ratio is smaller than a reference speed ratio corresponding to the predetermined speed ratio. A storage unit;
The control unit calculates a first speed ratio when the first line pressure becomes a target value of the second pressure with reference to the map when the prediction unit predicts that the belt slips. When the actual speed ratio of the continuously variable transmission is included between the first speed ratio and the reference speed ratio, the third valve is in the first state and the first line pressure is the first speed. The control device for a continuously variable transmission according to claim 2, wherein it is determined that the pressure is smaller than a target value of two pressures. The control unit matches the first pressure and the second pressure when the gear ratio of the continuously variable transmission is a predetermined gear ratio when the prediction unit does not predict that the belt will slip. And the normal control for controlling the first valve and the second valve so as to decrease the first pressure and increase the second pressure as the speed ratio is larger,
The control device includes:
An input unit for inputting a detection value of the first pressure by a hydraulic sensor;
A storage unit that stores a reference gear ratio corresponding to the predetermined gear ratio;
When the predicting unit predicts that the belt slips, the control unit has an actual speed ratio of the continuously variable transmission smaller than the reference speed ratio, and the detected value of the first pressure is the first pressure value. 3. The continuously variable step according to claim 2, wherein when the pressure is smaller than a target value of two pressures, the third valve is in the first state and the first line pressure is determined to be smaller than a target value of the second pressure. Transmission control device.   The control unit, when the prediction unit predicts that the belt slips, when the third valve is in the first state and the target value of the second pressure is smaller than the first line pressure or 5. The method according to claim 2, wherein when the third valve is in the second state, the second pressure is increased to a target value of the second pressure without increasing the first pressure. Control device for continuously variable transmission. A control method performed by a control device for a continuously variable transmission for a vehicle, which includes a drive-side first pulley, a driven-side second pulley, and a belt wound around the first pulley and the second pulley. There,
The vehicle includes a first valve that regulates a first pressure supplied to the first pulley, a second valve that regulates a second pressure supplied to the second pulley, the first pressure, and the second pressure. A hydraulic circuit having a third valve for controlling the line pressure, which is a control pressure of the pressure,
The third valve is mechanically switched to a first state in which the line pressure is set to a first line pressure depending on the first pressure in a range where the first pressure is greater than the second pressure, In a range where two pressures are greater than the first pressure, the line pressure is mechanically switched to a second state in which the line pressure is set to a second line pressure depending on the second pressure.
The control method is:
Predicting slippage of the belt based on the state of the vehicle;
Controlling the first valve and the second valve,
The step of controlling the first valve and the second valve includes the third valve when the third valve is in the first state when it is predicted that the belt slips in the predicting step. The first pressure is increased to increase the first line pressure while maintaining the valve in the first state, and the second pressure is increased using the increased first line pressure as a source pressure. A control method for a continuously variable transmission, including the step of controlling the first valve and the second valve.

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