JP2008075709A - Vehicle controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To quickly realize a required connected state by accurately detecting the N-Idle oil pressure of a starting clutch in the neutral control. <P>SOLUTION: A transmission controller 12 judges whether a vehicle is in a stopped state and further whether neutral control executing conditions including at least the select lever of a CVT1 positioned in a running range are established or not. When it is judged that the neutral control executing conditions are established, the idling speed control (ISC) of an engine 5 is stopped, and the inlet air quantity just before the stop of the ISC is kept. Then, the oil pressure Pc of the starting clutch is reduced until the increasing rate of the engine speed due to the reduction of the oil pressure Pc of the starting clutch becomes smaller than a required value. When the increasing rate of the engine speed has become smaller than the required value, the oil pressure Pc of the starting clutch at that time is kept as the N-Idle oil pressure, and further the ISC of the engine 5 is started again. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle control device, and more particularly to neutral control performed when the vehicle is stopped.

  In a vehicle equipped with a torque converter and an automatic transmission, when the vehicle is in a stationary state and the select lever is kept in the travel range, the automatic transmission start clutch is put into a slip state, thereby generating torque. Neutral control is performed in which the converter is released from the stalled state, the engine load is reduced, and the fuel consumption while the vehicle is stopped is suppressed.

  In order to control the start clutch to the slip state, the hydraulic pressure supplied to the start clutch may be controlled so that the deviation between the engine speed and the turbine speed of the torque converter becomes a target value. A sensor for detecting the rotational speed is required, which increases the cost.

Therefore, in the automatic transmission described in Patent Document 1, when a predetermined neutral control execution condition is satisfied, the hydraulic pressure supplied to the starting clutch is decreased, and the change in the intake air amount at that time is monitored, The hydraulic pressure (N-Idle hydraulic pressure) at which the starting clutch is slightly engaged (N-Idle state) is detected, and the engagement state of the starting clutch is controlled based on this. The reason why the starting clutch is set to such an N-Idle state is to shorten the time until the starting clutch is in a state where power can be transmitted at the next start, and to reduce the start delay.
JP 2004-162845 A

  However, since idling speed control (ISC) for maintaining the engine speed at a predetermined idling speed is usually performed while the vehicle is stopped, even if the hydraulic pressure supplied to the starting clutch is reduced, There is a delay before the change appears in the intake air amount, and the sensitivity is poor.

  In addition, during low-speed operation such as idling, the engine speed constantly fluctuates. If feedback control of the intake air amount is performed in real time, the fluctuation amplitude of the engine speed increases, so the ISC It needs to be done slowly. For this reason, if the intake air amount fluctuates in a short time by reducing the hydraulic pressure supplied to the starting clutch, there is a possibility that the ISC becomes unstable. It is necessary to do it slowly.

  For the above reasons, in the conventional method, it takes time until the starting clutch is brought into a desired engagement state in the neutral control, and the accuracy of the detected N-Idle hydraulic pressure is not sufficient.

  The present invention has been made in view of such technical problems of the prior art. In neutral control, the N-Idle hydraulic pressure of the starting clutch is detected with high accuracy, and a desired engagement state is quickly realized. With the goal.

  According to the present invention, it is determined whether or not the neutral control execution condition is satisfied, which includes at least the satisfied condition that the vehicle is stationary and the transmission select lever is in the travel range, and the neutral control execution condition is satisfied. If it is determined, the ISC for controlling the engine rotation speed to a predetermined idle rotation speed is stopped, and the intake air amount of the engine immediately before the ISC stop is maintained.

  Then, the hydraulic pressure of the start clutch is decreased until the increase rate of the engine speed (the increase amount per unit time or the increase amount per unit decrease amount of the clutch hydraulic pressure) by decreasing the hydraulic pressure of the start clutch becomes smaller than a predetermined value. If the increase rate of the engine rotation speed becomes smaller than a predetermined value, the hydraulic pressure of the starting clutch at that time is maintained as the neutral idle hydraulic pressure (N-Idle hydraulic pressure), and the engine ISC is restarted.

  According to the present invention, the N-Idle state of the starting clutch is determined based on the increase rate of the engine speed when the clutch hydraulic pressure of the starting clutch is decreased. When judging the N-Idle state of the starting clutch, the ISC of the engine is stopped in advance, so that the change in the engine speed due to the reduction of the clutch hydraulic pressure becomes clear, and the N-Idle state is accurately judged. can do. Further, the idle rotation speed control and the change in the engine rotation speed due to the clutch hydraulic pressure decrease do not interfere with each other, and it is possible to prevent the idle rotation speed control from becoming unstable.

  Further, since the N-Idle state is determined from the rate of increase of the engine rotational speed, a sensor for detecting the turbine rotational speed is not required, compared to a configuration that is determined from the deviation between the rotational speed of the engine and the turbine rotational speed of the torque converter. The configuration of the apparatus is simplified and the cost can be reduced.

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

  FIG. 1 shows a schematic configuration of a belt type continuously variable transmission (hereinafter referred to as “CVT”) 1. The primary pulley 2 and the secondary pulley 3 are arranged so that their V-grooves are aligned, and a V-belt 4 is stretched over the V-grooves of these pulleys 2 and 3. An engine 5 is arranged coaxially with the primary pulley 2, and a torque converter 6 and a forward / reverse switching mechanism 7 are provided between the engine 5 and the primary pulley 2 in order from the engine 5 side.

  The torque converter 6 includes a pump impeller 6a connected to the output shaft of the engine 5, a turbine runner 6b connected to the input shaft of the forward / reverse switching mechanism 7, a stator 6c, and a lockup clutch 6d.

  The forward / reverse switching mechanism 7 includes a double pinion planetary gear set 7 a as a main component, and its sun gear is coupled to the turbine runner 6 b of the torque converter 6 and the carrier is coupled to the primary pulley 2. The forward / reverse switching mechanism 7 further includes a starting clutch 7b that directly connects the sun gear and the carrier of the double pinion planetary gear set 7a, and a reverse brake 7c that fixes the ring gear. When the starting clutch 7b is engaged, the input rotation via the torque converter 6 from the engine 5 is directly transmitted to the primary pulley 2, and when the reverse brake 7c is engaged, the input rotation via the torque converter 6 from the engine 5 is reversed. Is transmitted to the primary pulley 2.

  The rotation of the primary pulley 2 is transmitted to the secondary pulley 3 via the V-belt 4, and the rotation of the secondary pulley 3 is transmitted to the driving wheel (not shown) via the output shaft 8, the gear set 9 and the differential gear device 10.

  In order to make it possible to change the gear ratio between the primary pulley 2 and the secondary pulley 3 during the power transmission described above, one of the conical plates forming the V grooves of the primary pulley 2 and the secondary pulley 3 is fixed to the fixed conical plates 2a, 3a. The other conical plates 2b and 3b are movable conical plates that can be displaced in the axial direction.

  These movable conical plates 2b and 3b are directed toward the fixed conical plates 2a and 3a by supplying the primary pulley pressure Ppri and the secondary pulley pressure Psec created using the line pressure as the original pressure to the primary pulley chamber 2c and the secondary pulley chamber 3c. As a result, the V-belt 4 is frictionally engaged with the conical plate, and power is transmitted between the primary pulley 2 and the secondary pulley 3.

  At the time of shifting, the width of the V groove of both pulleys 2 and 3 is changed by the differential pressure between the primary pulley pressure Ppri and the secondary pulley pressure Psec generated corresponding to the target gear ratio, and the V belt 4 for the pulleys 2 and 3 is changed. The target gear ratio is realized by continuously changing the wrapping arc diameter.

  The primary pulley pressure Ppri and the secondary pulley pressure Psec are controlled by the shift control hydraulic circuit 11 together with the hydraulic pressure supplied to the start clutch 7b that is engaged when the forward travel range is selected and the reverse brake 7c that is engaged when the reverse travel range is selected. The shift control hydraulic circuit 11 performs control in response to a signal from the transmission controller 12.

  The transmission controller 12 includes a signal from the primary pulley rotation sensor 13 that detects the rotation speed Npri of the primary pulley 2, a signal from the secondary pulley rotation sensor 14 that detects the rotation speed Nsec of the secondary pulley 3, and a secondary pulley pressure. A signal from the secondary pulley pressure sensor 15 that detects Psec, a signal from the accelerator operation amount sensor 16 that detects the operation amount APO of the accelerator pedal, a selection range signal from the inhibitor switch 17 that detects the position of the select lever, and CVT1 A signal from the oil temperature sensor 18 that detects the oil temperature TMPt of the engine, a signal relating to the operating state of the engine (engine rotation speed Ne, fuel injection time, cooling water temperature TMPE, etc.) from the engine controller 19 that controls the engine 5, brake Detects pedal operation status A signal from a brake switch 20 that, a signal from an idle switch 21 for detecting that the accelerator pedal is released, is input.

  When the vehicle is in a stopped state with the select lever in a traveling range such as the forward D range, L range, sports traveling S range, reverse traveling R range, etc., the torque converter 6 is connected to the turbine runner 6b. Of the engine 5 (hereinafter referred to as “turbine rotation speed”) Nt becomes a stalled state, the load of the engine 5 increases, and the fuel consumption increases.

  Therefore, the transmission controller 12 determines that the neutral control execution condition is satisfied when all of the following conditions are satisfied, and the hydraulic pressure (hereinafter referred to as “clutch hydraulic pressure”) supplied to the starting clutch of the forward / reverse switching mechanism 7. The neutral control for lowering Pc and setting the starting clutch to the N-Idle state is executed.

  The N-Idle state is an upper limit torque at which the clutch hydraulic pressure Pc is a neutral idle hydraulic pressure (hereinafter referred to as “N-Idle hydraulic pressure”), the gap between the clutch plates is zero, and the start clutch can transmit. A certain clutch capacity Tcc is in a state close to zero. According to this neutral control, the load on the engine 5 is reduced, and the fuel consumption can be reduced. The starting clutch refers to a frictional engagement element (clutch, brake) existing on the power transmission system path at the time of starting. In this embodiment, the starting clutch is the starting clutch 7b and the reverse brake 7c when moving backward.

  The determination of the N-Idle state is made from the increase rate Δε of the engine rotation speed Ne when the clutch hydraulic pressure Pc is decreased. The increase rate Δε gradually decreases as the starting clutch approaches the N-Idle state, and becomes almost zero when the start clutch exceeds the N-Idle state. Therefore, since the increase rate Δε is smaller than the predetermined value, the N-Idle state is changed. It is possible to judge. The predetermined value corresponding to the N-Idle state is a value near zero, and is obtained in advance by experiments or the like.

  In the situation where the neutral control execution condition is satisfied, the engine controller 19 normally performs idle rotation speed control (hereinafter referred to as “ISC”) in which the engine rotation speed Ne is feedback-controlled to a predetermined idle rotation speed. However, when the neutral control is executed, a command is issued to the engine controller 19 to stop the ISC, the ISC is stopped, and the intake air amount Qa immediately before the neutral control is executed is maintained.

  In the neutral control, the ISC is stopped, as described above, because the N-Idle state is determined from the increase rate Δε of the engine rotational speed Ne when the clutch hydraulic pressure Pc is decreased. This is because it is necessary to clarify the influence on the speed Ne. When the ISC is operating, the change in the engine rotational speed Ne due to the decrease in the clutch hydraulic pressure Pc is reversed by the ISC, and it becomes difficult to determine the N-Idle state from the increase rate Δε of the engine rotational speed Ne. . Further, since the ISC is controlled relatively slowly, it is also for preventing the ISC from becoming unstable due to a sudden change in the engine rotational speed Ne due to a decrease in the clutch hydraulic pressure Pc.

  FIG. 2 shows a relationship among the clutch hydraulic pressure Pc, the clutch capacity Tcc, the clutch transmission torque Tc, the engine rotational speed Ne, and the turbine rotational speed Nt when the vehicle is in a stopped state. It is assumed that the ISC is stopped.

  When the clutch hydraulic pressure Pc is higher than the fully engaged hydraulic pressure, the turbine runner 6b is connected to the vehicle drive shaft, and the turbine rotational speed Nt is equal to the rotational speed of the vehicle drive shaft and is zero. Since the torque converter 6 is in a stalled state in which only the pump impeller 6a is rotated by the engine 5 while the turbine runner 6b is stopped, the load on the engine 5 increases.

  From this state, the clutch hydraulic pressure Pc is lowered, and when the clutch hydraulic pressure Pc becomes lower than the fully engaged hydraulic pressure, the starting clutch starts to slip and the turbine runner 6b starts to rotate. When the torque converter 6 is released from the stalled state, the load on the engine 5 is reduced and the engine rotational speed Ne is increased.

  When the clutch hydraulic pressure Pc is further decreased and the starting clutch approaches the N-Idle hydraulic pressure at which the N-Idle state is reached, the increase rate of the engine rotation speed Ne decreases. When the clutch hydraulic pressure Pc becomes lower than the N-Idle hydraulic pressure, the increase rate of the engine rotational speed Ne becomes substantially zero, and the turbine rotational speed Nt becomes substantially equal to the engine rotational speed Ne. Further, both the clutch capacity Tcc and the transmission torque Tc become zero.

  The reason why the N-Idle hydraulic pressure is higher than zero is that the starting clutch displaces the piston against the urging force of the return spring by the clutch hydraulic pressure Pc and displaces the clutch plate in the engagement direction. This is because when the force that pushes the piston is less than the biasing force of the return spring, a gap is generated between the clutch plates. That is, the hydraulic pressure at the last minute that pushes the piston against the return spring to make the gap between the clutch plates zero is the N-Idle hydraulic pressure.

  3 and 4 show the contents of the neutral control performed by the transmission controller 12, and the N-Idle state is determined by the process shown in FIG. 3, and the N-Idle hydraulic pressure learning value Px is set and set. The verification of the learned N-Idle hydraulic pressure learning value Px is performed by the process shown in FIG.

  First, the processing shown in FIG. 3 will be described. In step S1, the vehicle speed VSP, the state of the brake switch 20, the position of the select lever, the state of the idle switch 21, the engine coolant temperature TMPE, and the CVT oil temperature TMPt are read.

In step S2, it is determined whether a neutral control execution condition is satisfied. The neutral control execution conditions are, for example, the following five conditions:
Vehicle speed VSP = 0 (stopped)
Brake switch = ON (the brake pedal is depressed)
Idle switch = ON (the accelerator pedal is released)
Select lever position = traveling range 60 ° C. ≦ engine cooling water temperature TMPE ≦ 90 ° C.
60 ° C ≦ CVT oil temperature TMPt ≦ 100 ° C
Is determined to be established when all of the above are established. The reason why the engine coolant temperature TMPe and the CVT oil temperature TMPt are determined is to determine whether the engine 5 and CVT1 are in a stable state.

  In step S3, a command is issued to the engine controller 19 to stop the ISC of the engine 5. As a result, the ISC of the engine 5 is stopped, and the intake air amount Qa of the engine 5 is thereafter maintained at the value immediately before the ISC is stopped.

  In step S4, a command is issued to the shift control hydraulic circuit 11 to decrease the clutch hydraulic pressure Pc by a predetermined hydraulic pressure ΔP. In step S5, it is determined whether the increase rate Δε of the engine rotation speed Ne due to the decrease in the clutch hydraulic pressure Pc is smaller than a predetermined value. The increase rate Δε may be an increase amount of the engine rotation speed Ne per unit time (= ΔNe / Δt), or an increase amount of the engine rotation speed Ne per unit decrease amount of the clutch hydraulic pressure (= ΔNe / ΔP). May be.

  When the increase rate Δε is larger than the predetermined value, the process returns to step S4, and steps S4 and S5 are repeated until the increase rate Δε becomes smaller than the predetermined value. Here, the clutch oil pressure Pc is decreased by a constant oil pressure ΔP, but the amount of decrease at the beginning of the decrease may be increased, and the amount of decrease may be decreased as time elapses.

  When the increase rate Δε is smaller than the predetermined value, it is determined that the starting clutch is in the N-Idle state, so the process proceeds to Step S6, and the clutch oil pressure Pc at that time is set as the N-Idle oil pressure learning value Px. To do.

  In step S7, a command is issued to the engine controller 19 to resume the ISC of the engine 5. Thereby, the rotational speed Ne of the engine 5 is again controlled to a predetermined idle rotational speed.

  With the above processing, the N-Idle hydraulic pressure learning value Px is set, and the clutch hydraulic pressure Pc is maintained at the N-Idle hydraulic pressure learning value Px until the neutral control release condition is satisfied. The neutral control cancellation condition is determined to be satisfied when any one of the above five conditions constituting the neutral control execution condition is not satisfied. When the cancellation condition is satisfied, the clutch hydraulic pressure Pc is determined according to the cause of the cancellation. Responsiveness is higher than full fastening hydraulic pressure.

  For example, when the select lever is operated from the forward range to the reverse range and released, or when the accelerator pedal is depressed and released, it is necessary to immediately make the start clutch ready to transmit power. With the responsiveness, the clutch hydraulic pressure Pc is increased beyond the fully engaged hydraulic pressure. On the other hand, it is transmitted when the select lever is released by operating from the travel range to the stop range or neutral range, or when the engine coolant temperature TMPe or CVT oil temperature TMPt is out of the predetermined range. In order to suppress a shock caused by a sudden increase in torque, the clutch hydraulic pressure Pc is increased relatively slowly to a level higher than the fully engaged hydraulic pressure.

  Next, the process shown in FIG. 4 will be described. This process verifies whether the starting clutch is in the N-Idle state by setting the clutch hydraulic pressure Pc to the N-Idle hydraulic pressure learning value Px. If the starting clutch is not in the N-Idle state, the starting clutch is in the N-Idle state. The clutch hydraulic pressure Pc is changed so as to approach the value, and the N-Idle hydraulic pressure learned value Px is updated to the clutch hydraulic pressure Pc after the change. The verification of the N-Idle hydraulic pressure learning value Px is performed once per minute, for example.

  According to this, first, in step S11, a command is issued to the engine controller 19 to stop the ISC of the engine 5. As a result, the ISC of the engine 5 is stopped, and the intake air amount Qa of the engine 5 is thereafter maintained at the value immediately before the ISC is stopped.

  In step S12, a command is issued to the shift control hydraulic circuit 11 to increase the clutch hydraulic pressure Pc from the N-Idle hydraulic pressure learned value Px by a predetermined hydraulic pressure ΔP. When the clutch hydraulic pressure Pc is increased by a predetermined hydraulic pressure ΔP, the engine rotational speed Ne changes by ΔNe (negative value).

In step S13, it is determined whether the absolute value of the engine rotational speed change amount ΔNe is smaller than the upper limit fluctuation range ε _{2. In} step S14, the absolute value of the engine rotational speed change amount ΔNe is determined from the lower limit fluctuation range ε ₁ (≈0). Is also determined.

  FIG. 5 is a diagram showing the relationship between the clutch hydraulic pressure Pc and the engine rotational speed Ne before and after the N-Idle hydraulic pressure. When the clutch hydraulic pressure Pc is in the vicinity of the N-Idle hydraulic pressure, the engine rotation speed Ne slightly changes when the clutch hydraulic pressure Pc is changed (state B in the figure). However, when the clutch hydraulic pressure Pc becomes smaller than the N-Idle hydraulic pressure, the clutch hydraulic pressure Pc hardly changes even when the clutch hydraulic pressure Pc is changed (in the state of A in the figure). Conversely, when the clutch hydraulic pressure Pc becomes larger than the N-Idle hydraulic pressure, The fluctuation range when changed is increased (state C in the figure).

Therefore, the transmission controller 12 determines that the absolute value of the engine rotation speed change amount ΔNe due to the clutch oil pressure Pc being increased by the predetermined oil pressure ΔP has a lower limit fluctuation width ε ₁ (first predetermined amount) and an upper limit fluctuation width ε ₂ ( The second predetermined amount), and if so, it is determined that the clutch hydraulic pressure Pc is substantially equal to the N-Idle hydraulic pressure, the process proceeds to step S15, and the clutch hydraulic pressure increased in step S12 is determined. Pc is returned to the original, and the value of the N-Idle hydraulic pressure learning value Px is maintained as it is.

On the other hand, when the absolute value of the engine rotation speed change amount ΔNe is larger than the upper limit fluctuation range ε ₂ , the clutch hydraulic pressure Pc is excessively higher than the N-Idle hydraulic pressure. In this case, the process proceeds to step S17, and the clutch hydraulic pressure A command is issued to the shift control hydraulic circuit 11 to lower Pc by a predetermined hydraulic pressure ΔP. Then, in step S18, it is determined whether the absolute value of the engine speed change amount ΔNe resulting from this has become smaller than the upper limit fluctuation range ε _2. If not, the process returns to step S17, and the clutch hydraulic pressure Pc is still N−. The shift control hydraulic circuit 11 is instructed to decrease the clutch hydraulic pressure Pc by a predetermined hydraulic pressure ΔP until it is determined that the hydraulic pressure is higher than the Idle hydraulic pressure and becomes smaller than the upper limit fluctuation range ε ₂ .

When the absolute value of the engine rotational speed change amount ΔNe becomes smaller than the upper limit fluctuation range ε ₂ , the process proceeds to step S21, and the N-Idle hydraulic pressure learned value Px is updated to the clutch hydraulic pressure Pc at that time.

On the other hand, when the absolute value of the engine rotation speed change amount ΔNe is smaller than the lower limit fluctuation range ε ₁ , the clutch hydraulic pressure Pc is excessively lowered below the N-Idle hydraulic pressure, so that the routine proceeds to step S19 and the clutch hydraulic pressure Pc is set to the predetermined hydraulic pressure. A command is given to the shift control hydraulic circuit 11 to increase by ΔP, and the shift control hydraulic circuit is configured to increase the clutch hydraulic pressure Pc by a predetermined hydraulic pressure ΔP until the absolute value of the engine rotation speed change amount ΔNe resulting from this increases below the lower limit fluctuation range ε _1. 11 is issued (steps S19 and S20).

When the absolute value of the engine speed change amount ΔNe exceeds the lower limit fluctuation range ε ₁ , the process proceeds to step S21, and the N-Idle hydraulic pressure learning value Px is updated to the clutch hydraulic pressure Pc at that time.

Here, the absolute value of the engine speed change amount ΔNe when the clutch oil pressure Pc is increased from the N-Idle oil pressure learning value Px by a predetermined oil pressure ΔP is between the lower limit fluctuation width ε ₁ and the upper limit fluctuation width ε ₂ . The N-Idle hydraulic pressure learning value Px is verified depending on whether or not the absolute value of the engine speed change amount ΔNe when the N-Idle hydraulic pressure learning value Px is lowered by the predetermined hydraulic pressure ΔP is the lower limit fluctuation width ε ₁ . The N-Idle hydraulic pressure learning value Px may be verified depending on whether it is within the upper limit fluctuation range ε ₂ .

  FIG. 6 is a flowchart showing processing when the clutch hydraulic pressure Pc is lowered to verify the N-Idle hydraulic pressure learned value Px. The process is substantially the same as the process shown in FIG. 4 and steps S11 to S21 in FIG. 4 correspond to steps S31 to S41 in FIG. Thus, the N-Idle hydraulic pressure learning value Px can also be verified by a method of lowering the clutch hydraulic pressure Pc from the N-Idle hydraulic pressure learning value Px by a predetermined hydraulic pressure ΔP.

  FIG. 7 is a time chart showing how the neutral control is performed.

  When the neutral control execution condition is satisfied at time t1, the ISC of the engine 5 is stopped and the clutch hydraulic pressure Pc is lowered.

  When the clutch hydraulic pressure Pc is lower than the fully engaged hydraulic pressure (time t2), the starting clutch starts to slip and the load on the engine 5 decreases. Since the intake air amount Qa of the engine 5 is kept constant by stopping the ISC, the engine rotational speed Ne increases as the load decreases. Further, since the turbine runner 6b that has been stopped together with the drive shaft until then starts to rotate, the turbine rotation speed Nt also increases.

  When the clutch hydraulic pressure Pc further decreases and the starting clutch approaches the N-Idle state, the starting clutch slips further increases and the load on the engine 5 further decreases, so that the increase rate Δε of the engine rotational speed Ne gradually becomes zero. Get closer. If the increase rate Δε falls below a predetermined value, the transmission controller 12 determines that the starting clutch is in the N-Idle state, and sets the clutch hydraulic pressure at that time as the N-Idle hydraulic pressure learning value (time t3).

  Thereafter, the ISC is restarted and the clutch hydraulic pressure Pc is maintained at the N-Idle hydraulic pressure learning value, but the N-Idle hydraulic pressure learning value Px is verified every predetermined time.

  From time t4 to t5, the clutch oil pressure Pc is increased from the N-Idle oil pressure learned value Px by a predetermined oil pressure ΔP, and the N-Idle oil pressure learned value is verified based on the engine speed change amount ΔNe at that time.

In this example, since the engine speed change amount ΔNe is within the lower limit fluctuation range ε ₁ and the upper limit fluctuation range ε ₂ , it is determined that the N-Idle hydraulic pressure learning value Px is the N-Idle hydraulic pressure, The verification is completed only by returning the clutch oil pressure Pc to the original N-Idle oil pressure learning value Px. However, if it does not fall between the lower limit fluctuation range ε ₁ and the upper limit fluctuation range ε ₂ , the clutch hydraulic pressure Pc is increased or decreased, and the N-Idle hydraulic pressure learning value Px is updated to a larger value or a smaller value. Then, the clutch hydraulic pressure Pc and the N-Idle hydraulic pressure learning value Px are brought close to the N-Idle hydraulic pressure.

  The neutral control performed by the transmission controller 12 has been described above. The operational effects of the present invention are summarized as follows.

  The transmission controller 12 determines whether the neutral control execution condition is satisfied. If it is determined that the neutral control execution condition is satisfied, the transmission controller 12 stops the ISC of the engine 5 and the intake air amount of the engine 5 immediately before the ISC stop. Maintain Qa. Then, the clutch hydraulic pressure Pc is decreased until the increase rate Δε of the engine rotation speed Ne by decreasing the clutch hydraulic pressure Pc becomes smaller than a predetermined value. When the increase rate Δε becomes smaller than the predetermined value, The starting clutch hydraulic pressure Pc is maintained as the N-Idle hydraulic pressure, and the idling rotational speed control is resumed.

  When the N-Idle hydraulic pressure is searched by decreasing the clutch hydraulic pressure Pc, the engine ISC is stopped. Therefore, the change in the engine rotational speed Ne due to the decreased clutch hydraulic pressure Pc becomes clear, and the N-Idle state The determination and the search for the N-Idle hydraulic pressure can be performed with high accuracy. Further, the ISC can be prevented from becoming unstable without interference between the idle rotation speed control and the change in the engine rotation speed due to the decrease in the clutch hydraulic pressure Pc. Further, since the N-Idle state is determined from the increase rate Δε of the engine rotation speed Ne, the configuration of the apparatus can be simplified and the cost can be reduced (effect of the invention according to claim 1).

  Further, the transmission controller 12 verifies the N-Idle hydraulic pressure retrieved by the above processing. Specifically, the clutch hydraulic pressure Pc when the increase rate Δε of the engine rotation speed Ne becomes smaller than a predetermined value is set as the N-Idle hydraulic pressure learning value Px, the ISC of the engine 5 is stopped, and the clutch hydraulic pressure Pc is set. The N-Idle hydraulic pressure learning value Px is changed by a predetermined hydraulic pressure ΔP.

Then, it is determined whether the absolute value of the change amount ΔNe of the engine rotational speed Ne due to the change of the clutch hydraulic pressure Pc is between the lower limit fluctuation range ε ₁ and the upper limit fluctuation range ε _2. Pc is returned to the original, and the N-Idle hydraulic pressure learning value Px is maintained. On the other hand, when the absolute value of the change amount ΔNe of the engine rotational speed Ne is smaller than the lower limit fluctuation range ε ₁ , the clutch hydraulic pressure Pc is increased and the N-Idle hydraulic pressure learning value Px is updated to the increased clutch hydraulic pressure Pc. When it is larger than the upper limit fluctuation range ε ₂ , the clutch hydraulic pressure Pc is decreased, and the N-Idle hydraulic pressure learned value Px is updated to the decreased clutch hydraulic pressure Pc.

  By performing such verification processing, it is possible to confirm whether the N-Idle hydraulic pressure learning value Px is not deviated from the N-Idle hydraulic pressure (the effect of the invention according to claim 2), and the N-Idle hydraulic pressure learning value. When Px deviates from the N-Idle oil pressure, the clutch oil pressure Pc is changed so as to reduce the deviation, and the N-Idle oil pressure learning value Px is updated to the changed clutch oil pressure Pc. Can be brought closer to the N-Idle state with higher accuracy (the effects of the inventions of claims 3 and 4).

  The embodiment of the present invention has been described above, but the above embodiment is merely one example of application of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. Absent.

It is a schematic block diagram of the belt-type continuously variable transmission to which this invention is applied. It is a figure showing the relation of clutch oil pressure, clutch capacity, clutch transmission torque, engine rotation speed, and turbine rotation speed when the vehicle is stopped. In the flowchart which showed the content of neutral control, the control of the part which searches N-Idle oil_pressure | hydraulic is shown. In the flowchart which showed the content of neutral control, control of the part which verifies N-Idle oil pressure learning value is shown. It is the figure which showed the relationship between the clutch hydraulic pressure Pc before and behind N-Idle hydraulic pressure, and the engine rotational speed Ne. In the flowchart which showed the content of neutral control, another example of the control of the part which verifies N-Idle hydraulic pressure learning value is shown. It is a time chart which showed a mode when neutral control is performed.

Explanation of symbols

1 Transmission (CVT)
DESCRIPTION OF SYMBOLS 5 Engine 6 Torque converter 6a Pump impeller 6b Turbine runner 7 Forward / reverse switching mechanism 7b Start clutch 7c Reverse brake 11 Shift control hydraulic circuit 12 Transmission controller 19 Engine controller 20 Brake switch 21 Idle switch

Claims (4)

In a vehicle control device in which the rotation of an engine is transmitted to drive wheels via an automatic transmission having a torque converter and a starting clutch,
Means for determining whether or not a neutral control execution condition is satisfied, which includes at least a condition that the vehicle is in a stationary state and the selection lever of the transmission is in a travel range;
When it is determined that the neutral control execution condition is satisfied, the idle rotation speed control for controlling the rotation speed of the engine to a predetermined idle rotation speed is stopped, and the engine immediately before stopping the idle rotation speed control is stopped. Means for maintaining the amount of intake air;
Means for decreasing the hydraulic pressure of the starting clutch until an increase rate of the rotational speed of the engine by decreasing the hydraulic pressure of the starting clutch becomes smaller than a predetermined value;
Means for maintaining the hydraulic pressure of the starting clutch at that time as a neutral idle hydraulic pressure when the increasing rate of the rotational speed of the engine is smaller than a predetermined value, and restarting the idle rotational speed control;
A vehicle control device comprising: Means for setting a hydraulic pressure of the starting clutch as a neutral idle hydraulic pressure learning value when an increase rate of the rotational speed of the engine becomes smaller than the predetermined value;
Means for stopping the idle speed control and changing the hydraulic pressure of the starting clutch by a predetermined hydraulic pressure from the neutral idle hydraulic pressure learning value;
When the hydraulic pressure of the starting clutch is changed from the neutral idle hydraulic pressure learning value by the predetermined hydraulic pressure, the absolute value of the change amount of the engine speed is larger than the first predetermined amount and the first predetermined amount. Means for returning the oil pressure of the starting clutch to the neutral idle oil pressure learned value and maintaining the neutral idle oil pressure learned value when the predetermined amount of 2 is between,
The vehicle control device according to claim 1, further comprising:   If the absolute value of the amount of change in engine speed when the hydraulic pressure of the starting clutch is changed from the neutral idle hydraulic pressure learning value by the predetermined hydraulic pressure is smaller than the first predetermined amount, the starting clutch 3. The vehicle control apparatus according to claim 2, further comprising means for increasing the hydraulic pressure and updating the neutral idle hydraulic pressure learning value to the hydraulic pressure after the start clutch is increased.   If the absolute value of the amount of change in engine speed when the hydraulic pressure of the starting clutch is changed from the neutral idle hydraulic pressure learning value by the predetermined hydraulic pressure is greater than the second predetermined amount, the starting clutch 4. The vehicle control device according to claim 2, further comprising means for reducing the oil pressure and updating the neutral idle oil pressure learned value to the oil pressure after the start clutch is reduced.