JP2018146050A - Control device of continuously variable transmission and control method of continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device and control method of a continuously variable transmission, capable of compensating oil necessary for LOW return gear change during coast stop by an electric oil pump, with a pump capacity suppressed.SOLUTION: A controller 11 constitutes a control device of a continuously variable transmission 1 having, as a hydraulic power source S, a mechanical oil pump 2 driven by an engine ENG, and an electric oil pump 3. The controller 11 has a control unit configured to perform setting control of setting a transmission ratio change rate of LOW return gear change smaller in a case where the LOW return gear change of increasing a transmission ratio Ratio is performed during a coast stop of the engine ENG than that in a case where the LOW return gear change is performed in driving of the engine ENG.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a continuously variable transmission control device and a continuously variable transmission control method.

  In Patent Document 1, in an engine automatic stop vehicle having a mechanical oil pump driven by an engine and an electric oil pump, the electric oil pump is driven at a coast stop when the engine is stopped and the mechanical oil pump is not driven. It is disclosed that hydraulic oil is supplied to a continuously variable transmission.

JP 2012-52640 A

  During the coast stop, the vehicle startability and reacceleration after that can be improved by performing a LOW reverse shift that increases the gear ratio of the continuously variable transmission. On the other hand, in this case, it is necessary to cover the hydraulic oil necessary for the LOW reverse shift with an electric oil pump.

  However, when an electric oil pump is provided in addition to the mechanical oil pump, the electric oil pump is usually provided as an auxiliary to the mechanical oil pump. For this reason, there exists a possibility that the situation where it is difficult to cover hydraulic oil required with an electric oil pump may arise. It is also conceivable to increase the pump capacity of the electric oil pump in order to cope with the above situation. However, in this case, the electric oil pump is increased in size and power consumption is increased, which may be disadvantageous in terms of in-vehicle performance and energy.

  The present invention has been made in view of such a problem, and is a continuously variable transmission that enables an electric oil pump to supply oil necessary for a LOW reverse shift during a coast stop while suppressing pump capacity. It is an object of the present invention to provide a control device and a control method for a continuously variable transmission.

  A control device for a continuously variable transmission according to an aspect of the present invention is a control device for a continuously variable transmission having a mechanical oil pump driven by power of a drive source and an electric oil pump as a hydraulic power source. Compared to the second case where the LOW return shift is performed when the drive source is driven, in the first case where the LOW return shift that increases the gear ratio of the step transmission is performed at the coast stop of the drive source, A control unit that performs setting control to set a small change ratio of the gear ratio of the LOW return shift.

  According to another aspect of the present invention, there is provided a control method for a continuously variable transmission having a mechanical oil pump driven by the power of a drive source and an electric oil pump as a hydraulic source, the shift of the continuously variable transmission being In the first case where the LOW return shift for increasing the ratio is performed at the coast stop of the drive source, the LOW return shift is compared with the second case in which the LOW return shift is performed at the time of driving the drive source. There is provided a control method for a continuously variable transmission, including setting a speed ratio change ratio to be small.

  According to these aspects, when the LOW return shift is performed at the coast stop, the flow rate of the oil required for the LOW return shift can be reduced by setting the speed ratio change rate of the LOW return shift to be small. . For this reason, according to these aspects, it is possible to cover the oil necessary for the LOW return shift during the coast stop with the electric oil pump while suppressing the pump capacity.

It is a figure which shows the principal part of a continuously variable transmission. It is a figure which shows an example of control of 1st Embodiment with a flowchart. It is a figure which shows an example of the 1st shift map in which the 1st shift line was set. It is a figure which shows an example of the 2nd shift map in which the 2nd shift line was set. It is a figure which shows an example of the timing chart corresponding to control of 1st Embodiment. It is a figure which shows an example of the timing chart in the case of a comparative example. It is a figure which shows an example of control of 2nd Embodiment with a flowchart.

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

(First embodiment)
FIG. 1 is a schematic configuration diagram showing a main part of a continuously variable transmission 1. The continuously variable transmission 1 is a belt-type continuously variable transmission and is provided in a vehicle. The continuously variable transmission 1 is transmitted with the power of the engine ENG that constitutes the drive source of the vehicle.

  The continuously variable transmission 1 includes a mechanical oil pump 2, an electric oil pump 3, a strainer 4, an oil reservoir 5, a first check valve 6, a second check valve 7, and a control valve unit 8. And a controller 11. The continuously variable transmission 1 further includes a pulley part PLY, a clutch part CL, a torque converter TC, and a lubrication part LB.

  The mechanical oil pump 2 is driven by the power of the engine ENG. The mechanical oil pump 2 sucks oil from the oil reservoir 5 via the strainer 4 and supplies the oil to the control valve unit 8 via the first check valve 6. The electric oil pump 3 sucks oil from the oil reservoir 5 via the strainer 4 and supplies the oil to the control valve unit 8 via the second check valve 7.

  Specifically, the electric oil pump 3 is connected to a portion of the supply oil path from the mechanical oil pump 2 to the control valve unit 8 on the downstream side of the first check valve 6 via the second check valve 7. The More specifically, the electric oil pump 3 has a pump unit 31 connected in this way.

  The electric oil pump 3 further includes a motor 32 and an inverter 33. The motor 32 drives the pump unit 31. Specifically, the motor 32 is configured by a three-phase AC motor. The inverter 33 supplies current to the motor 32. Specifically, the inverter 33 converts the direct current from the battery BATT into a three-phase alternating current and supplies the converted current to the motor 32.

  The motor 32 is provided with a rotation speed sensor 34 for detecting the rotation speed of the motor 32. The inverter 33 is provided with a temperature sensor 35. Signals from the rotation speed sensor 34 and the temperature sensor 35 are input to the inverter 33 and further to the controller 11.

  The mechanical oil pump 2 constitutes a main oil pump, and the electric oil pump 3 constitutes a sub oil pump provided as an auxiliary to the mechanical oil pump 2. In the electric oil pump 3, specifically, the pump capacity is set smaller than that of the mechanical oil pump 2. The mechanical oil pump 2 and the electric oil pump 3 constitute a hydraulic pressure source S of the continuously variable transmission 1.

  The strainer 4 filters the oil. The strainer 4 is provided in the oil reservoir 5. The oil reservoir 5 stores, for example, oil drained from the control valve unit 8, oil that has circulated through the lubrication part LB, and the like.

  The first check valve 6 allows the flow of oil in the direction from the mechanical oil pump 2 toward the control valve unit 8 and blocks the flow in the reverse direction. The second check valve 7 allows the flow of oil in the direction from the electric oil pump 3 toward the control valve unit 8 and blocks the flow in the reverse direction.

  The control valve unit 8 is a hydraulic control circuit, and oil is supplied from the control valve unit 8 to, for example, a pulley part PLY, a clutch part CL, a torque converter TC, and a lubrication part LB.

  The pulley portion PLY includes a primary pulley and a secondary pulley, and hydraulic actuators that drive the primary pulley and the secondary pulley. The pulley part PLY constitutes a variator VA together with a belt wound around the primary pulley and the secondary pulley.

  The variator VA is a continuously variable transmission mechanism of the continuously variable transmission 1. In the present embodiment, the transmission ratio of the variator VA constitutes the transmission ratio Ratio of the continuously variable transmission 1. The transmission ratio Ratio is controlled by controlling the flow rate of oil supplied to the primary pulley of the variator VA, specifically, the hydraulic actuator that drives the primary pulley.

  The clutch portion CL is configured to include a hydraulic forward clutch FWD / C that is engaged when the vehicle moves forward and transmits power, and a hydraulic reverse brake REV / B that is engaged when the vehicle moves backward and transmits power. The For example, a forward / reverse switching mechanism can be applied to the clutch portion CL.

  The torque converter TC performs torque transmission via the working fluid. In the torque converter TC, oil is supplied to the hydraulic lockup clutch LU. The torque converter TC is supplied with oil as a working fluid. Oil is also supplied from the control valve unit 8 to the lubrication part LB where lubrication is required in the continuously variable transmission 1.

  The controller 11 is an electronic control device and constitutes a control device for the continuously variable transmission 1. The controller 11 includes a signal from the rotational speed sensor 34 and a signal from the temperature sensor 35, a signal from the rotational speed sensor 21 for detecting the rotational speed Ne of the engine ENG, and an accelerator opening indicating the amount of operation of the accelerator pedal. A signal from the accelerator opening sensor 22 for detecting the degree APO, a signal from the vehicle speed sensor 23 for detecting the vehicle speed VSP, and the like are input.

The controller 11 further includes, for example, a signal from the rotational speed sensor 24 for detecting the input side rotational speed of the variator VA, a signal from the rotational speed sensor 25 for detecting the output side rotational speed of the variator VA, and a continuously variable transmission. A signal from the oil temperature sensor 26 for detecting the oil temperature T _OIL of the machine 1, a signal from the oil pressure sensor 27 for detecting the line pressure PL, and a selection for detecting the selection range RNG selected by the driver. A signal or the like from the range detection switch 28 is input. Specifically, the input side rotational speed of the variator VA is the primary pulley rotational speed Npri, and the variator VA output side rotational speed is the secondary pulley rotational speed Nsec.

  The controller 11 controls the control valve unit 8, the electric oil pump 3, and the like based on the input signal. The controller 11 controls the control valve unit 8 to control the variator VA, the forward clutch FWD / C, the reverse brake REV / B, the lockup clutch LU, and the like. In controlling the electric oil pump 3, the controller 11 controls the drive of the motor 32 by controlling the inverter 33, thereby controlling the drive of the pump unit 31.

  By the way, the continuously variable transmission 1 has a hydraulic system SYS. The hydraulic system SYS is a hydraulic system having a mechanical oil pump 2 and an electric oil pump 3 as a hydraulic source S. In this embodiment, in addition to the mechanical oil pump 2 and the electric oil pump 3, a strainer 4 and an oil storage unit 5, a first check valve 6, a second check valve 7, a control valve unit 8, a pulley part PLY, a clutch part CL, a torque converter TC, and a lubrication part LB. The In the hydraulic system SYS, the most upstream position is constituted by the strainer 4 and the most downstream position is constituted by the oil storing part 5.

  In the hydraulic system SYS, oil is likely to leak due to deterioration over time. For this reason, when supplying the oil necessary for the continuously variable transmission 1, the hydraulic source S needs to compensate for the oil that leaks.

  On the other hand, in a vehicle equipped with the continuously variable transmission 1, a LOW reverse shift that increases the gear ratio Ratio during a coast stop is performed in order to improve vehicle startability and reacceleration. The coast stop is a driving source automatic stop control during traveling, and is executed when a coast stop condition described later is satisfied. Specifically, in the LOW return shifting, the gear ratio Ratio is changed to the LOW side, that is, the direction in which the transmission ratio Ratio increases as the vehicle speed VSP decreases.

  During the coast stop, it is necessary to cover the hydraulic oil necessary for the LOW reverse shift with the electric oil pump 3. However, the electric oil pump 3 is provided as an auxiliary to the mechanical oil pump 2. For this reason, we are anxious about the situation where it is difficult to cover the hydraulic oil required by the electric oil pump 3. Specifically, for example, there is a concern that such a situation may occur when the oil leak amount Q1 of the hydraulic system SYS increases due to deterioration over time.

  It is also conceivable to increase the pump capacity of the electric oil pump 3 in order to cope with the above situation. However, in this case, there is a concern that the electric oil pump 3 is increased in size and power consumption, resulting in disadvantages in terms of in-vehicle performance and energy.

  In view of such circumstances, in this embodiment, the controller 11 performs the control described below.

  FIG. 2 is a flowchart illustrating an example of the control performed by the controller 11. The controller 11 is configured to have a control unit by executing the processing of this flowchart. The controller 11 can repeatedly execute the processing of this flowchart.

  In step S1, the controller 11 determines whether or not coasting is in progress. The LOW reverse shift is performed during coasting including during coast stop. The fact that the vehicle is running on the coast is, for example, that the vehicle speed VSP is greater than zero, the accelerator pedal is not depressed, the brake pedal is depressed, the forward range is selected in the continuously variable transmission 1, including. If a negative determination is made in step S1, the processing of this flowchart is temporarily terminated. If the determination is affirmative in step S1, the process proceeds to step S2.

  In step S2, the controller 11 determines whether or not a coast stop is being performed. Whether or not the coast stop is being performed can be determined, for example, by whether or not a coast stop condition that is a coast stop execution condition is satisfied.

  The coast stop condition includes that the vehicle speed VSP is lower than the predetermined vehicle speed VSP4, that the accelerator pedal is not depressed, that the brake pedal is depressed, and that the forward range is selected in the continuously variable transmission 1. The predetermined vehicle speed VSP4 is, for example, a vehicle speed at which the lockup clutch LU is released.

  In step S2, an affirmative determination is made when all of these constituent conditions constituting the coast stop condition are satisfied, and a negative determination is made when any of these constituent conditions is not satisfied. When the coast stop condition is satisfied, the engine ENG is automatically stopped. As a result, the mechanical oil pump 2 is stopped and the electric oil pump 3 supplies oil.

  If the determination in step S2 is affirmative, the process proceeds to step S3, and the controller 11 determines the speed ratio Ratio according to the first shift line CA. If a negative determination is made in step S2, the process proceeds to step S4, and the controller 11 determines the speed ratio Ratio according to the second shift line CB. The first shift line CA and the second shift line CB are set in advance in a shift map described below.

  3A and 3B are diagrams showing an example of the shift map. FIG. 3A shows an example of a first shift map in which a first shift line CA is set, and FIG. 3B shows an example of a second shift map in which a second shift line CB is set.

  First, contents common to FIGS. 3A and 3B will be described. The continuously variable transmission 1 is shifted based on a shift map. Specifically, a shift line is set for each accelerator opening APO in the shift map, and the continuously variable transmission 1 is shifted according to the shift line selected according to the accelerator opening APO. 3A and 3B illustrate the coast line C as the shift line.

  In the shift map, the operating point M of the continuously variable transmission 1 is indicated according to the vehicle speed VSP and the rotational speed Npri. In the shift map, the gear ratio Ratio is indicated by the slope of a line connecting the operating point M and the zero point of the shift map. Therefore, the shift line indicates the setting of the gear ratio Ratio according to the vehicle speed VSP.

  The continuously variable transmission 1 can be shifted between the highest line obtained by minimizing the transmission ratio Ratio and the lowest line obtained by maximizing the transmission ratio Ratio. The coast line C is set to the highest HIGH line when the vehicle speed VSP is equal to or higher than the predetermined vehicle speed VSP1, and in this case, the gear ratio Ratio is the highest HIGH gear ratio, that is, the minimum gear ratio. The predetermined vehicle speed VSP1 is a minimum value of the vehicle speed VSP corresponding to the highest line on the coast line C.

  During coasting, the operating point M moves on the coast line C between the highest and lowest lines while increasing the slope of the line connecting the operating point M and the zero point of the shift map as the vehicle speed VSP decreases. To do. For this reason, by performing the shift of the continuously variable transmission 1 according to the coast line C, it is possible to perform a LOW return shift that increases the gear ratio Ratio in accordance with a decrease in the vehicle speed VSP.

  Specifically, in the shift map, the gear ratio Ratio is determined according to the coast line C as follows, and the LOW return shift is performed. That is, the corresponding operating point M on the coast line C is specified based on the vehicle speed VSP, and the gear ratio Ratio corresponding to the specified operating point M is obtained. Thereby, the gear ratio Ratio is determined according to the coast line C. When the operating point M is between the highest HIGH line and the lowest LOW line, the LOW return shift is performed by performing the shift control of the continuously variable transmission 1 so as to achieve the determined transmission ratio Ratio. .

  The difference between FIG. 3A and FIG. 3B is as follows. The first shift map shown in FIG. 3A is referred to when the coast stop is being performed. In the first shift map, the first shift line CA is set as the coast line C. The second shift map shown in FIG. 3B is referred to when coasting is not being performed but coasting is not being performed. In the second shift map, the second shift line CB is set as the coast line C.

  The first shift line CA is set so that the ratio of change in the gear ratio of the LOW return shift is smaller than that of the second shift line CB. Specifically, in the first shift line CA, when the vehicle speed VSP becomes lower than the predetermined vehicle speed VSP3, the rotation speed Npri corresponding to the vehicle speed VSP is set to be smaller than that in the second shift line CB.

  The predetermined vehicle speed VSP3 is such that the peak value of the required discharge amount Qe_r of the electric oil pump 3 obtained when the LOW return shift is performed according to the second shift line CB instead of the first shift line CA during the coast stop is the first shift. It is set to be reduced by a LOW reverse shift according to line CA.

  The peak value is generated, for example, when the LOW reverse shift is completed, that is, when the vehicle speed VSP becomes the predetermined vehicle speed VSP2, as will be described later. Further, as the predetermined vehicle speed VSP3 is larger, the peak value is reduced, but instead, the shift time of the LOW return shift becomes longer.

  For this reason, the predetermined vehicle speed VSP3 is set in consideration of, for example, the balance between the peak value reducing action and the LOW reverse speed change action. The predetermined vehicle speed VSP3 can be set in advance within a range that is higher than the predetermined vehicle speed VSP2 and equal to or lower than the predetermined vehicle speed VSP4.

  By setting the first shift line CA in this manner, the change ratio of the LOW reverse shift, that is, the change ratio of the speed ratio Ratio according to the decrease in the vehicle speed VSP is reduced compared to the second shift line CB. Setting control can be performed.

  In the first transmission line CA set in this way, the vehicle speed VSP that sets the transmission ratio Ratio to the maximum LOW transmission ratio, that is, the maximum transmission ratio, is lower than that of the second transmission line CB. In other words, in the first transmission line CA, the transmission ratio Ratio does not become the maximum transmission ratio until the vehicle speed VSP becomes lower than that in the second transmission line CB.

  Specifically, in the second shift line CB, when the vehicle speed VSP reaches the predetermined vehicle speed VSP2, the operating point M is set to the maximum LOW line, and the speed ratio Ratio becomes the maximum speed ratio. The predetermined vehicle speed VSP2 is the maximum value of the vehicle speed VSP corresponding to the maximum LOW line in the second shift line CB.

  On the other hand, in the first transmission line CA, even if the vehicle speed VSP reaches the predetermined vehicle speed VSP2, the transmission ratio Ratio does not become the maximum transmission ratio. This is because, in the first shift line CA, compared with the second shift line CB, the shift time of the LOW return shift is extended, and the peak value of the oil flow rate required for the LOW return shift is correspondingly increased. Means lower.

  If the peak value of the oil flow rate required for the LOW return shift decreases, the required discharge amount Qe_r of the electric oil pump 3 during the LOW return shift also decreases accordingly. For this reason, the pump capacity of the electric oil pump 3 can be reduced as the required discharge amount Qe_r becomes smaller.

  Returning to FIG. 2, after the speed ratio Ratio is determined in step S3 or step S4, the process proceeds to step S5, and the controller 11 calculates the speed change flow rate Qs based on the determined speed ratio Ratio. The transmission flow rate Qs is a flow rate of oil necessary to achieve the determined transmission ratio Ratio, and is a flow rate of oil supplied to the primary pulley in this embodiment.

  When the transmission gear ratio Ratio is determined according to the first transmission line CA, when the vehicle speed VSP is lower than the predetermined vehicle speed VSP3, the transmission gear ratio change rate is smaller than when the transmission gear ratio Ratio is determined according to the second transmission line CB. Therefore, the shift flow rate Qs is also reduced.

  In step S6, the controller 11 calculates a required discharge amount Qe_r of the electric oil pump 3. The required discharge amount Qe_r of the electric oil pump 3 is calculated from the sum of the oil leak amount Q1 of the hydraulic system SYS, the required actuator flow rate Q2 of the continuously variable transmission 1, and the required lubrication flow rate Q3 of the continuously variable transmission 1, for example. It can be calculated by subtracting the discharge flow rate Qm of the oil pump 2.

  The oil leak amount Q1 is the oil leak amount of the entire hydraulic system SYS, and is preset by map data or the like. Therefore, the oil leak amount Q1 can be calculated based on a parameter that defines the oil leak amount Q1 using map data or the like.

Specifically, the oil leak amount Q1 increases as the line pressure PL is higher, and increases as the oil temperature _TOIL is higher. Therefore, in the present embodiment, the oil leak amount Q1 is set in advance according to the line pressure PL and further the oil temperature T _OIL . The oil leak amount Q1 may be further set according to parameters other than the line pressure PL and the oil temperature T _OIL .

  The required actuator flow rate Q2 is the sum of the above-described shift flow rate Qs and the oil flow rate Qa to the hydraulic actuator that is required to supply oil other than for shifting. The flow rate Qa can be calculated based on the command pressure for the hydraulic actuator to which oil is supplied. The hydraulic actuator includes, for example, a hydraulic actuator that drives a secondary pulley, forward clutch FWD / C, reverse clutch REV / B, lockup clutch LU, and the like.

  The required lubrication flow rate Q3 is a flow rate of oil required in the lubrication part LB, and is set in advance by map data or the like. For this reason, the required lubricating flow rate Q3 can be calculated based on a parameter that defines the required lubricating flow rate Q3 by map data or the like. The required lubrication flow rate Q3 can be set according to the driving state of the vehicle including the vehicle speed VSP, the accelerator opening APO, and the like.

  The discharge flow rate Qm of the mechanical oil pump 2 can be calculated based on the rotational speed Ne. The discharge flow rate Qm becomes zero during the coast stop when the engine ENG is stopped.

  In step S7, the controller 11 issues a drive instruction for the electric oil pump 3 based on the calculated required discharge amount Qe_r. Thereby, the flow rate of oil for the required discharge amount Qe_r is supplied from the electric oil pump 3. Further, the LOW return shift is performed by supplying the oil flow rate corresponding to the shift flow rate Qs from the electric oil pump 3 in the form included in the flow rate. After step S7, the process of this flowchart is once ended.

  FIG. 4 is a timing chart corresponding to the flowchart shown in FIG. 2, that is, an example of a timing chart in the present embodiment. FIG. 5 is a diagram illustrating an example of a timing chart in the case of the comparative example. The comparative example shows a case where the LOW return shift is completed according to the second shift line CB. In the case of this embodiment, it corresponds to the first case where the LOW return shift is performed when the engine ENG is coast-stopped, and in the case of the comparative example, it corresponds to the second case where the LOW return shift is performed when the engine ENG is driven. .

  In both the present embodiment and the comparative example, the change is the same before the timing T2. At timing T1, the brake pedal is depressed at a vehicle speed VSP that is equal to or lower than a predetermined vehicle speed VSP1, and a LOW return shift is started. As a result, the gear ratio Ratio gradually increases. The accelerator opening APO is zero, and the input torque to the continuously variable transmission 1 is negative. Prior to timing T2, the vehicle speed VSP is equal to or higher than the predetermined vehicle speed VSP3. Therefore, before the timing T2, the speed ratio Ratio is determined according to the second shift line CB.

  At timing T2, the vehicle speed VSP becomes less than the predetermined vehicle speed VSP3. In this example, the predetermined vehicle speed VSP3 is set to the predetermined vehicle speed VSP4. For this reason, at the timing T2, as a result of the coast stop condition being satisfied, the coast stop is started, and the rotational speed Ne and the total discharge flow rate Qt start to decrease accordingly.

  The total discharge flow rate Qt is the sum of the discharge flow rate Qm of the mechanical oil pump 2 and the discharge flow rate Qe of the electric oil pump 3, and is the discharge flow rate Qm before the timing T3. At timing T3, the driving of the electric oil pump 3 is started before the engine ENG is completely stopped.

  In the case of the comparative example shown in FIG. 5, even if the coast stop is started at the timing T2, the gear ratio Ratio is determined according to the second shift line CB. That is, the LOW return shift is performed according to the second shift line CB. For this reason, in the comparative example, the change in the gear ratio Ratio after the timing T2 becomes abrupt, and the LOW return shifting is completed at the timing T4.

  In the case of the present embodiment shown in FIG. 4, when the coast stop is started at timing T2, the gear ratio Ratio is determined according to the first shift line CA. For this reason, the shift time of the LOW return shift is extended, and the change in the gear ratio Ratio after the timing T2 becomes more gradual than in the comparative example. As a result, the LOW return shift is completed at timing T5 after timing T4.

  Next, the line pressure PL, the flow rate, and the required discharge amount Qe_r will be described.

  First, the contents common to the present embodiment and the comparative example will be described. The line pressure PL is set so as to satisfy the required flow rate Qt_r. The required flow rate Qt_r is a flow rate of oil required in the continuously variable transmission 1, and is specifically the sum of an oil leak amount Q1, a required actuator flow rate Q2, and a required lubrication flow rate Q3. The required flow rate Qt_r increases as the shift flow rate Qs in the LOW return shift increases. The oil leak amount Q1 increases as the line pressure PL increases.

  Prior to the timing T3, the mechanical oil pump 2 is still driven, and as a result of the total discharge flow rate Qt exceeding the required flow rate Qt_r, there is no shortage of oil flow. At timing T3, the discharge flow rate Qm falls below the required flow rate Qt_r. Even in the comparative example, the total discharge flow rate Qt is maintained at the required flow rate Qt_r or more by the electric oil pump 3.

  However, in the case of the comparative example, the LOW return shift is performed according to the second shift line CB, so that the line pressure PL is increased so as to satisfy the shift flow rate Qs at this time. Further, when the line pressure PL is increased, the oil leak amount Q1 increases, so that it is necessary to supplement the oil by the amount that the oil leak amount Q1 increases.

  As a result, in the case of the comparative example, the required flow rate Qt_r continues to increase until the LOW return shift is completed, and reaches a peak at the completion of the LOW return shift, specifically immediately before the completion of the LOW return shift. The line pressure PL and the oil leak amount Q1 also reach a peak when the LOW return shift is completed.

  If the peak value of the required flow rate Qt_r is large, the peak value of the required discharge amount Qe_r of the electric oil pump 3 also increases accordingly. When the peak value of the required discharge amount Qe_r is large, the required flow rate Qt_r further increases when the oil leak amount Q1 further increases due to deterioration with time of the hydraulic system SYS. As a result, the electric oil pump 3 may not be able to cover the required flow rate Qt_r.

  In the case of the present embodiment, a LOW return shift is performed according to the first shift line CA from the timing T3. The shift flow rate Qs at this time is smaller than that of the comparative example as described above, coupled with an increase in the shift time of the LOW return shift. For this reason, the line pressure PL is lower than that in the comparative example, and when the line pressure PL is lowered, the oil leak amount Q1 is also reduced.

  As a result, in the case of the present embodiment, the required flow rate Qt_r is suppressed from the timing T3 and the peak value of the required flow rate Qt_r is also lower than in the comparative example. For this reason, the peak value of the required discharge amount Qe_r of the electric oil pump 3 is also lowered, so that a margin is generated in the pump capacity. Therefore, it is possible to cope with an increase in the amount of oil leak Q1 due to the deterioration of the hydraulic system SYS over time without increasing the pump capacity of the electric oil pump 3 at least by the margin.

  Next, main effects of the present embodiment will be described.

  The controller 11 constitutes a control device for the continuously variable transmission 1 having the mechanical oil pump 2 driven by the power of the engine ENG and the electric oil pump 3 as the hydraulic power source S. When the LOW return shift for increasing the gear ratio Ratio is performed when the engine ENG is coast-stopped, the controller 11 sets the ratio change ratio of the LOW return shift as compared to the case where the LOW return shift is performed when the engine ENG is driven. The configuration includes a control unit that performs setting control to be set to a small value.

  According to such a configuration, when the LOW return shift is performed at the coast stop, the flow rate of the oil necessary for the LOW return shift, that is, the shift flow rate Qs is set by setting the speed ratio change rate of the LOW return shift small. Can be reduced. For this reason, according to such a configuration, it is possible to cover the oil required for the LOW reverse shift during the coast stop with the electric oil pump 3 while suppressing the pump capacity (corresponding to claims 1 and 6). Effect).

  The controller 11 changes the shift line of the continuously variable transmission 1 to a different shift line when the LOW return shift is performed when the engine ENG is coast-stopped, compared to when the LOW return shift is performed when the engine ENG is driven. Thus, the setting control is performed.

  According to such a configuration, since the setting control can be performed using the shift line, it is easy to realize in the continuously variable transmission 1 that performs the shift control according to the shift line (corresponding to claim 2). effect).

  The controller 11 performs the setting control according to the amount of oil leak in the hydraulic system SYS. With such a configuration, the controller 11 can supply the oil necessary for the LOW return shift during the coast stop with the electric oil pump 3 while suppressing the pump capacity (corresponding to claim 5). effect).

  Specifically, the oil leak amount in such a configuration can be set to the oil leak amount Q1. The oil leak amount in such a configuration may be an oil leak amount of a predetermined portion of the hydraulic system SYS. When the influence of oil leakage occurring due to deterioration with time in a predetermined part such as the variator VA is large, the influence of oil leakage in the hydraulic system SYS can be represented by the amount of oil leakage in the predetermined part. It is.

(Second Embodiment)
This embodiment is the same as the first embodiment except that the controller 11 is configured to perform the control described below. For this reason, below, the control which the controller 11 mainly performs by this embodiment is demonstrated.

  FIG. 6 is a flowchart illustrating an example of the control performed by the controller 11 in the present embodiment. This flowchart is the same as the flowchart shown in FIG. 2 except that step S2 ′ is added following the affirmative determination in step S2. For this reason, step S2 ′ will be mainly described here.

  In step S2 ′, the controller 11 determines whether or not deterioration with time has occurred in the hydraulic system SYS based on the deterioration state with time of the hydraulic system SYS. Specifically, the time-dependent deterioration state of the hydraulic system SYS is a time-dependent deterioration state that increases the oil leak amount Q1, and the oil leak amount Q1 tends to increase as the degree of deterioration with time increases. For this reason, the determination in step S2 ′ can be made specifically based on such a parameter indicating the state of deterioration over time.

  Specifically, in step S2 ′, it is determined whether or not deterioration over time of a predetermined degree has occurred as deterioration over time. Further, it is determined whether or not deterioration with time has occurred in a portion of the hydraulic system SYS downstream of the hydraulic source S, that is, on the side where oil is supplied from the hydraulic source S.

  The predetermined degree defines the degree of deterioration over time that may cause a situation in which the electric oil pump 3 cannot supply the oil required for the LOW return shift during the coast stop. In some cases, such a situation is considered to occur. The predetermined degree can be set in advance as a setting value for a parameter that indicates a deterioration state with time.

  The portion of the hydraulic system SYS downstream of the hydraulic source S is, for example, the portion after the control valve unit 8 including the line pressure control valve in the hydraulic system SYS. In this case, when deterioration with time occurs in the part, it can be determined that deterioration with time occurs as a whole for the part.

  A portion downstream of the hydraulic power source S in the hydraulic system SYS may be a predetermined portion such as a variator VA among the downstream portions. In the case where the influence of oil leakage generated due to deterioration with time in a predetermined portion is large, the determination can be performed in this way.

  Whether or not deterioration with time has occurred, for example, with respect to the oil to be controlled by a hydraulic control device such as a line pressure control valve or the oil supplied to the hydraulic actuator, It can be determined whether or not the difference from the indicated oil amount is greater than a predetermined value. According to such determination, it is possible to determine whether or not deterioration with time has occurred based on the amount of oil that is actually leaked.

  The total actual oil amount can be calculated, for example, by calculating the actual oil amount based on the actual pressure detected by the pressure sensor, such as the actual pressure of the line pressure PL detected by the hydraulic sensor 27, and integrating the calculated actual oil amount for a predetermined period. . The total actual oil amount may be calculated using a flow meter.

  The total command oil amount can be calculated by calculating the command oil amount based on the command pressure and integrating the calculated command oil amount for a predetermined period. The predetermined period can be set in advance to such a length that a significant difference is obtained between the total actual oil amount and the total indicated oil amount, for example, several hours. The predetermined value is a setting value corresponding to the predetermined degree, and is a setting value when the magnitude of the difference is used as a parameter.

  Whether or not deterioration with time has occurred may be determined, for example, based on whether or not the total travel distance of the vehicle exceeds a predetermined distance. The predetermined distance is a setting value corresponding to the predetermined degree, and is a setting value when the total travel distance is used as a parameter.

  If an affirmative determination is made in step S2 ′, it is determined that deterioration with time has occurred, and the process proceeds to step S3. If a negative determination is made in step S2 ′, it is determined that deterioration with time has not occurred, and the process proceeds to step S4.

  In other words, in the present embodiment, even when the coast stop is being performed, if there is no deterioration over time in the hydraulic system SYS, the gear ratio Ratio is determined according to the second shift line CB. Therefore, in the present embodiment, the gear ratio Ratio is determined according to the first shift line CA when deterioration with time occurs in the hydraulic system SYS during the coast stop.

  Next, main effects of the present embodiment will be described.

  In the present embodiment, the controller 11 performs the above-described setting control when the degree of deterioration over time is equal to or greater than a predetermined degree based on the state of deterioration over time of the hydraulic system SYS.

  According to such a configuration, when the oil leak amount Q1 is small, the LOW return shift is performed according to the second shift line CB, and when the oil leak amount Q1 is large, the LOW return shift is performed according to the first shift line CA. be able to. For this reason, it is possible to perform an appropriate LOW return shift according to necessity in light of the oil leak amount Q1 (effect corresponding to claim 3).

  In the present embodiment, the controller 11 performs the above-described setting control when the degree of deterioration over time is equal to or greater than a predetermined degree based on the state of deterioration over time in a portion of the hydraulic system SYS downstream of the hydraulic power source S.

  According to such a configuration, an appropriate LOW return shift according to the necessity is performed against the situation where the electric oil pump 3 cannot cover the required flow rate Qt_r due to deterioration with time on the side where oil is supplied from the hydraulic power source S. (Effects corresponding to claim 4).

  The time-dependent deterioration state of the hydraulic system SYS may be a time-dependent deterioration state of the electric oil pump 3, that is, a time-dependent deterioration state on the oil supply side. This is because even when the electric oil pump 3 deteriorates with time, a situation may occur in which the electric oil pump 3 cannot supply the required flow rate Qt_r.

  Whether or not the electric oil pump 3 has deteriorated with time is, for example, whether or not the magnitude of the difference between the total actual oil amount and the total indicated oil amount corresponding to each other within a predetermined period is larger than a predetermined value as described above. This can be determined by determining the electric oil pump 3. In this case, it is possible to perform an appropriate LOW return shift according to the necessity in light of the time-degraded state of the electric oil pump 3 (effect corresponding to claim 4).

  The temporal deterioration state of the hydraulic system SYS may be a temporal deterioration state of oil used as hydraulic oil in the continuously variable transmission 1. This is because the hydraulic oil used in the continuously variable transmission 1 is improved in viscosity by an additive or the like, and when it deteriorates with time, the viscosity decreases and the amount of oil leak Q1 increases.

  Whether the oil has deteriorated with time can be determined, for example, by determining whether the total traveling distance of the vehicle exceeds a predetermined distance as described above. In this case, it is possible to perform an appropriate LOW return shift according to the necessity in light of the deterioration of oil over time (effect corresponding to claim 4).

  The embodiment of the present invention has been described above. However, the above embodiment only shows a part of application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. Absent.

  In the above-described embodiment, the case where the setting control is performed by changing the shift line of the continuously variable transmission 1 to a different shift line has been described. However, for example, in the speed change control of the continuously variable transmission 1, the setting control is a filter such as a low-pass filter that is used to feed back actual values such as the actual pressure of the hydraulic pressure supplied to the primary pulley and the actual speed ratio of the speed ratio Ratio Then, it may be performed by generating a primary delay or a secondary delay.

  In the above-described embodiment, the case where the first shift line CA is set to the first shift map and the second shift line CB is set to the second shift map has been described. However, the first shift line CA and the second shift line CB may be set to a common shift map, for example. In this case, when performing the LOW reverse shift, the shift map can be configured so that the first shift line CA is used when the coast stop is being performed, and the second shift line CB is used when the coast stop is not being performed. .

  In the above-described embodiment, the case where the engine ENG is automatically stopped in accordance with the establishment of the coast stop condition and the coast stop is being performed has been described. However, being in the coast stop includes, for example, the case where the automatic stop of the engine ENG is continued because the coast stop condition is satisfied during the fuel cut of the engine ENG.

  The fuel cut condition is a condition including that the accelerator pedal is not depressed and the vehicle speed VSP is higher than a predetermined vehicle speed. The predetermined vehicle speed is a vehicle speed VSP in a medium to high speed range, and can be set in advance.

  The fuel cut condition is satisfied when all of the conditions included in the fuel cut condition are satisfied, and is not satisfied when there is a restart request for the engine ENG. The engine ENG restart request is, for example, when the accelerator pedal is depressed. In the fuel cut, the lockup clutch LU is engaged.

  For example, the controller 11 may be a plurality of controllers configured to perform processing in a distributed manner, and may be configured to have a control unit by such a plurality of controllers.

DESCRIPTION OF SYMBOLS 1 Continuously variable transmission 2 Mechanical oil pump 3 Electric oil pump 8 Hydraulic control circuit 11 Controller (control part)
ENG engine (drive source)
S Hydraulic source SYS Hydraulic system

Claims (6)

A control device for a continuously variable transmission having a mechanical oil pump driven by the power of a drive source and an electric oil pump as a hydraulic source,
Compared to the second case in which the LOW return shift is performed when the drive source is driven, in the first case where the LOW return shift that increases the transmission ratio of the continuously variable transmission is performed when the drive source is coast-stopped. A control unit for performing setting control for setting a small ratio of the transmission ratio of the LOW return shift,
A control device for a continuously variable transmission. A control device for a continuously variable transmission according to claim 1,
The control unit performs the setting control by changing a shift line of the continuously variable transmission to a different shift line in the first case as compared to the second case.
A control device for a continuously variable transmission. A control device for a continuously variable transmission according to claim 1 or 2,
The control unit performs the setting control when the degree of deterioration over time is a predetermined degree or more based on a state of deterioration over time of the hydraulic system of the continuously variable transmission.
A control device for a continuously variable transmission. A control device for a continuously variable transmission according to claim 3,
The control unit has at least any one of a part of the hydraulic system downstream from the hydraulic power source, the electric oil pump, and oil used as hydraulic oil in the continuously variable transmission as a state of deterioration of the hydraulic system with time. The setting control is performed when the degree of deterioration over time is equal to or greater than the predetermined degree based on the state of deterioration over time.
A control device for a continuously variable transmission. A control device for a continuously variable transmission according to any one of claims 1 to 4,
The control unit performs the setting control according to an oil leak amount of a hydraulic system of the continuously variable transmission.
A control device for a continuously variable transmission. A control method for a continuously variable transmission having a mechanical oil pump driven by power of a drive source and an electric oil pump as a hydraulic source,
Compared to the second case in which the LOW return shift is performed when the drive source is driven, in the first case where the LOW return shift that increases the transmission ratio of the continuously variable transmission is performed when the drive source is coast-stopped. Setting a small change ratio of the gear ratio of the LOW return shift,
A control method for a continuously variable transmission.

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