JP2007292245A - Holding pressure controller for belt type cvt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a holding pressure controller for a belt type CVT, which reduces a holding pressure by improving estimation accuracy of engine torque, and improves fuel economy while suppressing slipping of a belt. <P>SOLUTION: The holding pressure controller for the belt type CVT is connected to an engine having an ignition timing control means 717 for retarding ignition timing when predetermined ignition timing retard conditions are satisfied. It is provided with: the transmission belt suspended between a drive side pulley and a driven side pulley and pressurized against each pulley by a predetermined holding pressure; an engine torque estimating means 720 for estimating the engine torque from an operating sate of the engine; and a holding pressure setting means 732 for setting the holding pressure on the basis of an engine torque estimate by the engine torque estimating means 720. It is composed such that a set value of the holding pressure is corrected upward when the ignition timing of the engine is retarded. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an apparatus for controlling a belt clamping force of a belt type CVT (continuously variable transmission) connected to an engine.

  Conventionally, a belt type CVT (continuously variable transmission) using a transmission belt (hereinafter also simply referred to as a belt) is known. In a general belt type CVT, an annular metal belt is hung between a driving pulley (also called a primary pulley) and a driven pulley (also called a secondary pulley). And it is comprised so that a gear ratio can be changed continuously (steplessly) by changing the ratio of the effective diameter of each pulley.

  The belt is clamped to each pulley with a predetermined clamping pressure in order to suppress slippage with each pulley. As the pinching pressure increases, slipping is less likely to occur and greater torque transmission is possible. However, on the other hand, the frictional force between the belt and each pulley generated by the pinching pressure acts as engine resistance. Therefore, it is desirable that the clamping pressure is small from the viewpoint of improving fuel consumption. Therefore, when these conflicting demands are combined, the best setting is to set the holding pressure as small as possible within a range where slippage can be suppressed over all operating conditions.

For example, Patent Document 1 discloses a relatively strong clamping pressure in an operation mode with a large engine torque and a relatively weak clamping pressure in an operation mode with a small engine torque.
JP 2003-13095 A

  By the way, when setting the actual clamping pressure, it is necessary to allow for a margin so that the belt does not slip even if the engine torque varies in the maximum direction within the range of the estimated accuracy. In the conventional engine torque estimation method, the estimation accuracy is not so high and a relatively large margin is required. For this reason, there has been a certain limit to improving the fuel consumption by reducing the clamping pressure.

  The present invention has been made in view of the above circumstances, and is a belt type CVT that can improve the fuel efficiency while reducing the pinching pressure by suppressing the estimation accuracy of the engine torque and suppressing the slip of the belt. An object is to provide a clamping pressure control device.

  The invention according to claim 1 for solving the above-described problem is a belt-type CVT clamping pressure control device connected to an engine having ignition timing control means for retarding the ignition timing when a predetermined ignition timing retard condition is satisfied. , A transmission belt that is hung between the driving pulley and the driven pulley and is clamped by each pulley with a predetermined clamping pressure, and engine torque estimation that estimates the engine torque from the operating state of the engine Means and a clamping pressure setting means for setting the clamping pressure based on the estimated engine torque value by the engine torque estimating means, and the setting value of the clamping pressure is determined when the ignition timing of the engine is retarded. Ascending correction is performed.

  According to a second aspect of the present invention, in the belt-type CVT clamping pressure control device according to the first aspect, the increase in the clamping pressure set value is corrected by the engine torque estimating means increasing the engine torque estimated value. It is made to be made.

  The invention of claim 3 is the belt-type CVT clamping pressure control device according to claim 1 or 2, characterized in that the increase correction amount of the clamping pressure set value increases as the engine load during ignition timing retard increases. To do.

  According to a fourth aspect of the present invention, in the clamping pressure control device for the belt type CVT according to any one of the first to third aspects, the increase correction amount of the clamping pressure set value is a low engine temperature during the ignition timing retard. It is characterized by being large.

  According to a fifth aspect of the present invention, in the belt-type CVT clamping pressure control device according to any one of the first to fourth aspects, the ignition timing retard condition is an acceleration time or an engine cold time. It is established when at least one of the three types of occurrence of knocking is satisfied.

  According to a sixth aspect of the present invention, in the belt-type CVT clamping pressure control device according to the fifth aspect, the increase correction amount of the clamping pressure set value is a value corresponding to each of the above-mentioned types of ignition timing retards. It is characterized by that.

  According to the first aspect of the present invention, as will be described below, it is possible to improve the fuel efficiency while reducing the clamping pressure by suppressing the estimation accuracy of the engine torque and suppressing the slipping of the belt.

  The inventor of the present application has noticed that there is a difference in the estimation accuracy of the engine torque depending on the operating state of the engine, particularly the ignition timing. When the combustion is performed at the normal ignition timing (normal operation), the estimation accuracy of the engine torque is higher than when the ignition timing is delayed (hereinafter also referred to as IG retard), that is, the variation in the estimated engine torque is small. is there. The present invention utilizes this, and reduces the clamping pressure as a whole by classifying the setting value of the clamping pressure between normal operation and IG retard.

  Conventionally, a substantially constant margin has been expected in estimating the engine torque during both normal operation and IG retard. In other words, during normal operation, despite the high estimation accuracy, a large margin similar to that at the time of IG retard with low estimation accuracy was expected. On the other hand, in the present invention, a small margin corresponding to high estimation accuracy may be expected during normal operation. As a result, the estimated torque of the engine torque can be reduced.

  On the other hand, at the time of IG retard in which the estimation accuracy is lower than that at the time of normal operation, the variation in the estimated value of the engine torque increases, so that there is a possibility that the belt becomes slippery with the same margin as at the time of normal operation. Therefore, according to the present invention, the slippage of the belt can be suppressed by correcting the increase of the clamping pressure during the IG retard. The increase correction amount is preferably an amount corresponding to the degree of decrease in the engine torque estimation accuracy. Since the estimation accuracy of the engine torque decreases as the IG retard amount (retard amount) increases, the increase correction amount may be increased as the IG retard amount increases accordingly.

  According to the second aspect of the present invention, since the increase correction is performed at the stage of engine torque estimation and the estimated engine torque is once determined, the clamping pressure can be obtained collectively using the estimated engine torque. Control and calculation can be simplified.

  According to the third and fourth aspects of the present invention, the increase correction amount of the clamping pressure can be set to an appropriate value corresponding to the estimated accuracy of the engine torque. If other conditions are the same, the estimation accuracy of the engine torque tends to decrease as the engine load increases and the engine temperature decreases. Therefore, the higher the engine load (Claim 3) and the lower the engine temperature (Claim 4), the more appropriate the value (preferably the necessary minimum level is desirable) by increasing the amount of increase in the clamping pressure. Can be set to

  According to the invention of claim 5, the effect of the present invention in which the clamping pressure is set for the normal operation and the IG retard can be remarkably obtained with respect to the engine that can obtain the following effects by performing the IG retard. Can do.

  The IG retard (chip retard) performed at the time of acceleration can moderate the shock (chip in shock) accompanying the transitional change by appropriately suppressing the increasing speed of the engine torque. The IG retard (cold retard) performed when the engine is cold can increase the warm-up performance by increasing the gas amount. IG retard (knock retard) performed at the time of occurrence of knocking can suppress knocking by reducing the combustion temperature.

  It is most effective to perform all of these IG retards (including the case of performing several simultaneously). However, one type or any two types may be performed.

  According to the sixth aspect of the present invention, it is possible to perform the optimum ascent correction according to the type of IG retard. In the same type of IG retard, the engine torque estimation accuracy usually decreases as the retard amount increases. Accordingly, the increase correction amount may be increased as the IG retard amount increases. However, when the types of IG retard are different, even if the retard amount is the same, the appropriate increase correction amount is not always the same. This is because the engine torque estimation accuracy varies depending on combustion stability and other factors, that is, the degree of variation in the estimated value may vary.

  Therefore, according to the present invention, the increase correction amount can be set for each type of IG retard. Therefore, whatever type of IG retard is performed, it is possible to set an optimum clamping pressure corresponding to the IG retard.

  It should be noted that it is preferable to set a small increase correction amount in this order for the same retard amount as the mutual relationship between the chip retard, the cold retard and the knock retard.

  In the case where a plurality of IG retards are performed, and when two or more types of IG retards are performed at the same time, it is only necessary to select the maximum one of the increase correction amounts obtained individually.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a schematic structure of an engine 100 and a belt type CVT (continuously variable transmission) 200 according to an embodiment of the present invention.

  First, the engine 100 will be described. The schematic configuration of the engine 100 includes an engine body 110, an intake passage 121, and an exhaust passage 122. The engine main body 110 includes a cylinder head, a cylinder block, and the like, and is provided with a plurality (four in this embodiment) of cylinders 112. A combustion chamber 114 is formed in each cylinder 112, and a spark plug 115 is provided at the top. The air-fuel mixture in the combustion chamber 114 is combusted by ignition of the spark plug 115, and the combustion energy is output to the engine output shaft 1 (crankshaft) via a piston (not shown).

  The engine body 110 is provided with a crank angle sensor 130 that detects the rotation angle of the engine output shaft 1, a knock sensor 131 that detects knocking, and a water temperature sensor 133 that detects cooling water temperature.

  An intake valve and an exhaust valve (not shown) are provided for each combustion chamber 114. These intake and exhaust valves are connected to branch passages from an intake passage 121 and an exhaust passage 122, respectively.

An air cleaner 120 that purifies the intake air is provided in the uppermost stream of the intake passage 121, and an air flow sensor 125 that detects the intake air amount is provided downstream thereof. Further, a throttle valve 123 for adjusting the intake air amount is provided downstream thereof. An intake manifold branching toward each cylinder 112 via a surge tank is formed downstream of the throttle valve 123, and an intake pressure sensor 126 (MAP sensor) for detecting intake pressure is provided. Near each cylinder 112, a fuel injection valve 116 for supplying fuel to each combustion chamber 114 is provided.

  Next, the CVT 200 will be described. The schematic configuration of the CVT 200 includes a torque converter 250 connected to the engine output shaft 1, a forward / reverse switching mechanism 300, a speed change mechanism 400 including a variable belt transmission, a speed reduction mechanism 500, and a differential mechanism 600. Become.

  The torque converter 250 is fixed to one side portion of the pump cover 7 coupled to the engine output shaft 1 and rotates integrally with the engine output shaft 1. The torque converter 250 faces the pump impeller 3. It has a turbine runner 4 rotatably provided in a converter chamber 7 a formed inside the pump cover 7, and a stator 5 interposed between the pump impeller 3 and the turbine runner 4. The turbine runner 4 is connected to a carrier 15 which is an input member of a forward / reverse switching mechanism 300 described later via the turbine shaft 2, and the stator 5 is connected to the transmission case 19 via the one-way clutch 8 and the stator shaft 9. It is fixed.

  A lockup piston 6 a is disposed between the turbine runner 4 and the pump cover 7, and the lockup clutch 6 is configured by the lockup piston 6 a and the pump cover 7. The lockup piston 6a is slidably attached to the turbine shaft 2, and is brought into contact with the pump cover 7 and integrated with the pump cover 7 by controlling the introduction or discharge of hydraulic pressure into the lockup chamber 10. The converter state separated from the pump cover 7 is selectively realized. In the lockup state, the engine output shaft 1 and the turbine shaft 2 are directly connected without any fluid. In the converter state, the engine torque is transmitted from the engine output shaft 1 to the turbine shaft 2 via the fluid. The

  The forward / reverse switching mechanism 300 selectively sets a forward state in which the rotation of the turbine shaft 2 of the torque converter 250 is transmitted to the transmission mechanism 400 as it is and a reverse state in which the rotation is transmitted to the transmission mechanism 400 in a reverse state. In this embodiment, the forward / reverse switching mechanism 300 is constituted by a double pinion type planetary gear unit. That is, a first pinion gear 13 and a second pinion gear 14 that mesh with the sun gear 12 and the ring gear 11 are attached to the carrier 15 that is splined to the turbine shaft 2. Sun gear 12 is splined to primary shaft 22 of transmission mechanism 400.

  Further, a clutch 16 is provided between the ring gear 11 and the carrier 15, and the ring gear 11 is selectively fixed to the transmission case 19 between the ring gear 11 and the transmission case 19. A brake 17 is provided.

  The forward / reverse switching mechanism 300 is configured as described above. When the clutch 16 is engaged and the brake 17 is released, the ring gear 11 and the carrier 15 are integrated, and the ring gear 11 is connected to the transmission case 19. Since the rotation of the turbine shaft 2 is possible, the rotation of the turbine shaft 2 is output from the sun gear 12 to the primary shaft 22 side as it is in the same direction (forward movement state).

  On the other hand, in a state where the clutch 16 is released and the brake 17 is engaged, the ring gear 11 is fixed to the transmission case 19 side, and the ring gear 11 and the carrier 15 can be relatively rotated. Is output from the sun gear 12 to the primary shaft 22 side in the reverse state via the first pinion gear 13 and the second pinion gear 14 (reverse drive state).

  That is, in the forward / reverse switching mechanism 300, the forward / reverse switching is executed by the selective operation of the clutch 16 and the brake 17.

  The speed change mechanism 400 includes a primary pulley 21 (drive-side pulley) that is coaxially disposed on the rear side of the forward / reverse switching mechanism 300 described above, and a secondary pulley 31 (driven) that is spaced apart from the primary pulley 21 and disposed in parallel. Side pulley) and a belt 20 hung between the pulleys 21 and 31.

  The primary pulley 21 has one end splined to the sun gear 12 of the forward / reverse switching mechanism 300, a fixed conical plate 23 integral with the primary shaft 22, and axial movement on the primary shaft 22. The movable conical plate 24 is arranged in a possible state. The conical friction surface of the fixed conical plate 23 and the conical friction surface of the movable conical plate 24 constitute a belt receiving groove 21a having a substantially V-shaped cross section.

  A cylindrical cylinder 25 is fixed on the outer surface side of the movable conical plate 24, and a piston 26 fixed on the primary shaft 22 side is fitted into the cylinder 25 in an oil-tight manner. The cylinder 25 and the movable conical plate 24 constitute a primary chamber 27. Hydraulic oil is introduced into the primary chamber 27 from a hydraulic circuit (not shown) via the first hydraulic control valve 27a. The movable conical plate 24 moves in the axial direction by increasing / decreasing the hydraulic pressure (primary hydraulic pressure) of the hydraulic oil, whereby the distance from the fixed conical plate 23 increases / decreases, and the effective diameter of the primary pulley 21 relative to the belt 20 is adjusted. The Further, the fixed conical plate 23 and the movable conical plate 24 sandwich the belt 20 by the primary hydraulic pressure, and the slip of the belt 20 is suppressed by the sandwiching pressure.

  The secondary pulley 31 basically has the same configuration as the primary pulley 21, and a fixed conical plate 33 is provided integrally with a secondary shaft 32 that is spaced apart from the primary shaft 22 and arranged in parallel. In addition, a movable conical plate 34 is provided so as to be movable on the secondary shaft 32. The conical friction surface of the fixed conical plate 33 and the conical friction surface of the movable conical plate 34 facing each other constitute a belt receiving groove 31a having a substantially V-shaped cross section.

  A cylindrical cylinder 35 is coaxially fixed on the outer surface side of the movable conical plate 34, and a piston 36 fixed to the secondary shaft 32 is oil-tightly inserted into the cylinder 35. . The piston 36, the cylinder 35, and the movable conical plate 34 constitute a secondary chamber 37. As in the primary pulley 21 side, hydraulic oil is introduced into the secondary chamber 37 from the hydraulic circuit via the second hydraulic control valve 37a. And the secondary pulley 31 also increases or decreases the distance between the movable conical plate 34 and the fixed conical plate 33 in the axial direction by increasing or decreasing the hydraulic pressure (secondary hydraulic pressure) of the hydraulic oil, similarly to the primary pulley 21. The effective diameter of the belt 20 is adjusted. Further, the fixed conical plate 33 and the movable conical plate 34 sandwich the belt 20 by the secondary hydraulic pressure, and the slip of the belt 20 is suppressed by the sandwiching pressure.

  Since the speed reduction mechanism 500 and the differential mechanism 600 are the same as those of the conventional general so-called final gear and differential gear, description of their structures is omitted.

  FIG. 2 is a control block diagram of a PCM 700 (powertrain control module) that controls a driving system (powertrain) including the engine 100 and the CVT 200.

  The PCM 700 is a control module that integrally controls the operation of the engine 100, the operation of the CVT 200, and the like, and includes a computer having a CPU, a ROM, a RAM, and the like. Specifically, a program stored in advance in a ROM (or RAM) is executed by the CPU, whereby the operation of each part of the power train is controlled.

  Hereinafter, in the description of the PCM 700, the part related to this embodiment will be mainly described. The PCM 700 receives detection signals from the air flow sensor 125, the intake pressure sensor 126, the crank angle sensor 130, the knock sensor 131, and the water temperature sensor 133 shown in FIG. Further, a detection signal from an accelerator opening sensor 134 for detecting the accelerator depression amount (accelerator opening) and a vehicle speed sensor 138 for detecting the vehicle speed, which are not shown, are also input to the PCM 700.

  The PCM 700 functionally includes an intake air amount control unit 710, a fuel injection control unit 715, an ignition timing control unit 717, an engine torque estimation unit 720, and a pulley control unit 730.

  The intake air amount control unit 710 sets an appropriate intake air amount based on the operating state such as the engine speed and the accelerator opening, and adjusts the opening of the throttle valve 123 according to the intake air amount.

  The fuel injection control unit 715 sets an appropriate fuel injection amount according to the intake air amount, and injects fuel from each fuel injection valve 116 at an appropriate injection timing for each cylinder 112.

  The ignition timing control unit 717 sets an appropriate ignition timing and generates an electric spark (spark) in the spark plug 115 of each cylinder 112. During normal operation of engine 100, the ignition timing is set to a timing earlier than the compression top dead center by a predetermined advance angle. The advance angle is set to a time (hereinafter referred to as the best torque advance angle kb) at which the highest engine torque (hereinafter referred to as the best torque kc) can be obtained in the operating state.

  The best torque advance angle kb is obtained in advance by experiments or the like, and is stored in the ignition timing control unit 717 as map data corresponding to the operating state. For example, it is stored in a two-dimensional map using engine speed and engine load (throttle opening) as parameters. The ignition timing control unit 717 sequentially sets the best torque advance angle kb by reading the corresponding value of the best torque advance angle kb from the two-dimensional map based on the engine rotation speed and the engine load during operation.

  On the other hand, when a predetermined ignition timing retard condition (hereinafter also referred to as IG retard condition) is satisfied, the ignition timing control unit 717 retards the ignition timing from the best torque advance angle kb (IG retard). In the present embodiment, three types of cold retard, tip retard and knock retard are set as operating states for executing the IG retard, and the IG retard condition is satisfied when each of the predetermined states is reached.

  The cold retard is an IG retard that is performed when the engine is not sufficiently warmed. The cold retard condition is established as the IG retard condition when the coolant temperature detected by the water temperature sensor 133 is equal to or lower than a predetermined temperature (for example, 60 ° C. or lower). When the cold retard is performed, the exhaust gas temperature rises due to an increase in the gas amount, and therefore the time for the engine temperature to rise to an appropriate temperature can be shortened. That is, the warm-up performance is improved.

  The chip retard is an IG retard performed at the time of acceleration when the accelerator is depressed relatively steeply. The chip retard condition is established as the IG retard condition when the change rate of the accelerator opening detected by the accelerator opening sensor 134 is equal to or greater than a predetermined value. When the chip retard is performed, the increase speed of the engine torque is moderately suppressed, so that the vibration of the shock system (chip in shock) accompanying the transient change can be mitigated.

  Knock retard is an IG retard performed when knocking occurs. When knocking is detected by knock sensor 131, the knock retard condition is satisfied as the IG retard condition. When knock retard is performed, the combustion temperature is reduced, so that knocking can be suppressed.

  The cold retard, the chip retard and the knock retard are each set with an IG retard amount corresponding to the operation state when the IG retard condition is established. As an example, FIG. 3 shows the setting characteristics of the amount of IG retard in the case of cold retard. 3 indicates the cooling water temperature (° C.) detected by the water temperature sensor 133, and the vertical axis indicates the IG retard amount (deg. CA (crank angle)). As shown by the characteristic H in this figure, the IG retard amount is set to a positive value in a temperature range lower than 60 ° C. where the cold retard condition is satisfied. And it is set so that the amount of IG retard increases as the temperature decreases. As described above, when the cold retard is performed, the warm-up performance is improved, but the effect is greater as the IG retard amount is larger. Therefore, the amount of IG retard is increased on the low temperature side where higher warm-up performance is required. In FIG. 3, the characteristic H is shown as a graph, but is actually stored as mapped numerical data.

  Similarly, for the chip retard and knock retard, the IG retard amount corresponding to the predetermined parameter is stored in the ignition timing control unit 717 as map data.

  Returning to FIG. 2, the description will be continued. The engine torque estimating unit 720 estimates an engine torque necessary for setting the clamping pressure of the belt in the clamping pressure setting unit 732 described later.

  FIG. 4 is a diagram for explaining the concept of the engine torque estimation method by the engine torque estimation unit 720. The abscissa indicates the IG advance angle (deg. CA) as a parameter indicating the ignition timing, and the ordinate indicates the estimated engine torque (N · m). A characteristic T102 indicated by a solid line is a characteristic of a value that is finally set as an estimated engine torque after performing necessary torque correction. On the other hand, a characteristic T101 indicated by a broken line is a characteristic of the estimated engine torque before torque correction. A characteristic T103 indicated by a two-dot chain line indicates an engine torque estimated value obtained by a conventional torque estimating method as a reference.

  First, the case where IG retard is not performed will be described. In this case, the ignition timing control unit 717 sets the IG advance angle to the best torque advance angle kb, and it is estimated that the engine torque at that time is the best torque kc. Similar to the best torque advance angle kb, the best torque kc is estimated by reading the engine rotational speed and the engine load from a preset two-dimensional map as parameters. Note that an estimation error is taken into consideration for this best torque kc, and an upper limit value of estimation variation (a relatively small value when IG retard is not performed) is set.

Next, the case where IG retard is performed will be described. When performing the IG retard, the engine torque is estimated in two stages. First, in the first stage, only the torque reduction due to the IG retard is considered with respect to the best torque kc when the IG retard is not performed, and the estimation accuracy (variation) is assumed to be the same as when the IG retard is not performed. Estimate engine torque. The estimated engine torque in this case is indicated by a characteristic T101. In the present embodiment, it is estimated that the engine torque decreases in a quadratic function with the IG retard. For example, when the estimated engine torque on the characteristic T101 in the case of IG advance angle = tg is T1, T1 = kc−ka · (kb−tg) ² is calculated. The coefficient ka is a coefficient given as a torque reduction allowance (torque slope) with respect to the IG retard amount, and the torque decrease allowance with respect to the IG retard amount increases as the coefficient ka increases. The coefficient ka is a value that varies depending on the engine characteristics and operating conditions. Like the best torque advance angle kb and the best torque kc, the coefficient ka is read from a preset two-dimensional map using the engine speed and the engine load as parameters. Is set.

  In the next second stage, the estimated engine torque is corrected to be increased by the amount that the estimation accuracy is reduced by the IG retard, that is, the variation is increased. For example, when the IG advance angle = tg, the estimated engine torque T2 after correction is calculated as T2 = T1 + dT (torque correction amount). The torque correction amount dT is set by reading from a preset two-dimensional map using the IG advance angle and the engine load as parameters, and details thereof will be described later with reference to FIG.

  The trajectory of the corrected estimated engine torque T2 obtained through the first and second stages in this way is the characteristic T102. When this characteristic T102 is compared with the estimated engine torque characteristic T103 obtained by the conventional torque estimation method, the IG advance is almost equal when the IG advance angle is minimum (when the IG retard amount is maximum), but the IG advance angle is the best torque advance. As it approaches the angle kb, T102 <T103, and the difference increases as the IG advance angle approaches the best torque advance angle kb. This is because the characteristic T103 expects the entire estimation variation including the presence or absence of the IG retard as a margin over the whole IG advance angle, whereas the characteristic 102 estimates that changes according to the IG advance angle. This is because the variation is expected as a margin at the corresponding IG advance angle. In other words, by improving the estimation accuracy, the margin that has been expected more than necessary is reduced.

  Next, the torque correction amount dT will be described in more detail. FIG. 4 shows the torque correction amount = dT when the IG advance angle = tg, but the appropriate value (necessary minimum value) of the torque correction amount dT varies depending on the type of IG retard. Therefore, in this embodiment, the control is such that the torque correction amount dT can be changed depending on the type of IG retard even at the same ignition advance angle tg.

  FIG. 5 is a conceptual diagram of map data used for obtaining the torque correction amount dT. As shown in this figure, the engine torque estimation unit 720 is provided with a map table corresponding to each type of IG retard in order to obtain a torque correction amount dT. Specifically, a torque correction table A for cold retard, a torque correction table B for chip retard, and a torque correction table C for knock retard are stored as numerical data.

  Here, the cold retard table A will be described. Actually, the table A is two-dimensional map data using the IG advance angle and the engine load as parameters, but FIG. 5 is a graph for showing the concept. The horizontal axis represents the IG advance angle, and the vertical axis represents the engine torque correction value.

  A characteristic T201 indicated by a solid line is a characteristic applied at a certain engine load. For example, the characteristic T201 ′ is lower when the load is lower than that, and T201 ″ is higher when the load is higher. Applied. That is, the engine torque correction value is set so as to increase as the IG advance angle decreases (as the IG retard amount increases) and as the engine load increases.

  When the cold retard condition is established, the characteristic H shown in FIG. 3 is first referred to, and the IG retard amount is obtained from the cooling water temperature at that time. Then, the IG advance angle is set as a value (a retarded value) smaller than the best torque advance angle kb by the IG retard amount. For example, when the IG advance angle is tg shown in FIG. 5 and the engine load is applied with the characteristic T201, the engine torque correction amount is obtained as the correction amount Ta shown in FIG. As is apparent with reference to FIGS. 3 and 5, the engine torque correction value is set to increase as the engine temperature decreases.

  For the table B for chip retard and the table C for knock retard, as in the case of table A, torque correction values are set as two-dimensional map data using IG advance angle and engine load as parameters. The torque correction value is set so as to increase as the IG advance angle decreases (as the IG retard amount increases) and as the engine load increases. Then, respective torque correction values Tb and Tc based on the IG advance angle at the time of engine torque estimation and the engine load are obtained.

  If the retard amount and the engine load are the same, the torque correction amount by the knock retard table C is generally the largest, and then the torque correction amount by the cold retard table A is large, and the chip retard table. The torque correction amount due to B is minimized.

  When any one of cold retard, chip retard and knock retard is executed, the torque correction values Ta, Tb or Tc read from the corresponding table A, B or C correspond to the torque correction amount dT. Used as In addition, two or more types of IG retard may be executed at the same time. In this case, the maximum of the torque correction values Ta, Tb or Tc read from the table corresponding to the executed IG retard Is used as the torque correction amount dT.

FIG. 6 is a schematic flowchart of engine torque estimation by the engine torque estimating unit 720. When this flowchart starts, first, in step S1, necessary data such as the engine speed and engine load (throttle opening) are read, and then the engine torque T1 before torque correction is estimated (step S3). As described above, T1 = kc−ka · (kb−tg) ² is obtained.

  Next, it is determined whether or not at least one type of IG retard is being executed (step S5). If YES, it is further determined whether or not it is a cold retard (step S9). If YES in step S9, a torque correction amount Ta for cold retard is provisionally set from the torque correction table A (step S11). In the case of NO at step S9, 0 is input as the torque correction amount Ta for cold retard (step S13).

  Subsequently, it is determined whether or not the IG retard is a chip retard (step S15). If YES in step S15, a torque correction amount Tb for chip retard is provisionally set from the torque correction table B (step S17). In the case of NO at step S15, 0 is input to the torque correction amount Tb for chip retard (step S19).

  Subsequently, it is determined whether or not the IG retard is a knock retard (step S21). If YES in step S21, a torque correction amount Tc for knock retard is provisionally set from the torque correction table C (step S23). In the case of NO at step S21, 0 is input to the torque correction amount Tc for knock retard (step S25).

  Then, among the torque correction amounts Ta, Tb and Tc temporarily set so far, the maximum one is set as the final torque correction amount dT (step S27). Then, the estimated engine torque T2 obtained in step S27 is added to the estimated engine torque T1 obtained in step S3 to obtain a corrected estimated engine torque T2 (step S31).

  Going back, if NO in step S5, that is, if no IG retard is executed, 0 is input to the torque correction amount dT (step S29). Therefore, in step S31, the estimated torque T1 is obtained as it is as the corrected estimated engine torque T2.

  Returning to FIG. 2, the description will be continued. The pulley control unit 730 sets a transmission gear ratio and a pinching pressure according to the operating state, and in order to realize this, the first hydraulic control valve 27a for the primary pulley 21 and the second hydraulic control valve 37a for the secondary pulley 31 are used. And a drive signal is output. Specifically, the pulley control unit 730 includes a transmission ratio setting unit 731, a clamping pressure setting unit 732, and a driving unit 733.

  The gear ratio setting unit 731 sets a target pulley ratio. The pulley ratio is a ratio between the rotation speed of the primary shaft 22 (primary rotation speed) and the rotation speed of the secondary shaft 32 (secondary rotation speed. In setting the target pulley ratio, first, the target primary rotation speed is set. This is set based on a preset shift diagram with the vehicle speed and throttle opening as parameters, and then the target pulley ratio is set as the ratio between the target primary rotational speed and the current secondary rotational speed. The current primary rotation speed and secondary rotation speed are detected by a primary rotation speed sensor and a secondary rotation speed sensor (not shown) and input to the PCM 700.

  The actual pulley ratio is calculated as the ratio between the current primary rotation speed and the current secondary rotation speed with respect to the target pulley ratio. If the target pulley ratio and the actual pulley ratio are equal to or within a predetermined deviation, no shift is performed. That is, the current actual pulley ratio is maintained. On the other hand, when the deviation between the target pulley ratio and the actual pulley ratio is greater than or equal to a predetermined value, a shift in a direction that brings the actual pulley ratio closer to the target pulley ratio is performed. In this case, the pulley ratio changing speed is also set as appropriate.

  The clamping pressure setting unit 732 sets the clamping pressure of the belt in the primary pulley 21 and the secondary pulley 31. This clamping pressure is set based on the estimated engine torque estimated by the engine torque estimating unit 720. For example, it is set with reference to map data set in advance using estimated engine torque as a parameter. The larger the estimated engine torque, the larger the clamping pressure is set.

  The drive unit 733 includes a first hydraulic control valve so that the pulley ratio becomes the target pulley ratio set by the transmission ratio setting unit 731 and the clamping pressure becomes the clamping pressure set by the clamping pressure setting unit 732. 27a and the second hydraulic control valve 37a are driven and controlled.

  For example, in order to increase the pulley ratio, the first hydraulic pressure control valve 27a and the second hydraulic pressure control valve 37a are driven and controlled in a direction in which the primary hydraulic pressure decreases relative to the secondary hydraulic pressure. As a result, in the primary pulley 21, the movable conical plate 24 moves to the side away from the fixed conical plate 23, and the groove width of the belt receiving groove 21a is increased. For this reason, the portion of the belt 20 that is hung on the primary pulley 21 moves to the inner diameter side along the conical friction surfaces of the fixed conical plate 23 and the movable conical plate 24. That is, the effective diameter is reduced, and the rotational speed of the primary shaft 22 is relatively increased. On the other hand, in the secondary pulley 31, the movable conical plate 34 moves to the fixed conical plate 33 side, and the groove width of the belt receiving groove 31a becomes narrow. Therefore, the portion of the belt 20 that is hung on the secondary pulley 31 moves to the outer diameter side along the conical friction surfaces of the fixed conical plate 33 and the movable conical plate 34. That is, the effective diameter is increased, and the rotational speed of the secondary shaft 32 is relatively reduced. In this way, the speed difference between the primary shaft 22 and the secondary shaft 32 increases, so the pulley ratio, which is the speed ratio between the two shafts, increases. In order to reduce the pulley ratio, the reverse control may be performed.

  For example, when increasing the clamping pressure, the first hydraulic control valve 27a and the second hydraulic control valve 37a are driven and controlled in a direction in which both the hydraulic pressure in the primary chamber 27 and the hydraulic pressure in the secondary chamber 37 increase. For example, when only the pinching pressure is increased with the pulley ratio being fixed without shifting, the secondary hydraulic pressure is first increased with the secondary pulley 31 as a reference. Then, the primary hydraulic pressure of the primary pulley 21 is increased so that the pulley ratio does not fluctuate. In order to reduce the clamping pressure, the opposite control may be performed.

  Next, a driving operation including engine 100 and CVT 200 will be described. During forward travel, the clutch 16 of the forward / reverse switching mechanism 300 is engaged. Therefore, power generated by combustion in each cylinder 112 of engine 100 is transmitted from engine output shaft 1 to primary shaft 22 through torque converter 250 in the same rotational direction as engine output shaft 1. Then, power is transmitted to the secondary shaft 32 via the belt 20 adjusted so as to have a target pulley ratio (speed ratio) corresponding to the operating state. At this time, slipping between the primary pulley 21 and the secondary pulley 31 and the belt 20 is suppressed by an appropriate clamping pressure corresponding to the estimated engine torque, so that proper power transmission from the primary pulley 21 to the secondary pulley 31 is achieved. It is done. The frictional force between the belt 20 and the pulleys 21 and 31 generated by the belt clamping pressure acts as an engine resistance, but is reduced by setting the clamping pressure as small as possible. Therefore, fuel efficiency is improved by reducing engine resistance. The power transmitted to the secondary shaft 32 is transmitted from the speed reduction mechanism 500 to the drive wheels (not shown) via the differential mechanism 600.

  When any of the cold retard condition, the chip retard condition, or the knock retard condition is satisfied during the operation of the engine 100, the ignition timing control unit 717 of the PCM 700 executes IG retard. When the IG retard is executed, the above-described warm-up performance improvement effect, chip-in shock reduction effect, or knocking suppression effect can be obtained.

  When the IG retard is executed, the estimation accuracy of the engine torque estimation unit 720 relatively decreases. However, the estimated engine torque is corrected to increase accordingly, and the clamping pressure set based on the estimated engine torque is also corrected to increase. Therefore, the belt slip is appropriately suppressed. In addition, since the torque correction amount is a minimum correction amount according to the degree of decrease in the estimation accuracy of the engine torque, the reduction margin of the fuel efficiency improvement effect due to the engine torque increase correction is suppressed to the minimum. .

  Further, when the vehicle speed is higher than a predetermined vehicle speed, the lockup clutch 6 of the torque converter 250 is locked. As a result, energy loss due to fluid slip of the torque converter 250 is eliminated, so that further improvement in fuel consumption is achieved.

  On the other hand, at the time of reverse traveling, the rotation direction of the turbine shaft 2 and the primary shaft 22 is reversed by engaging the brake 17 instead of the clutch 16. Therefore, it is possible to reverse the drive wheel and reverse the vehicle.

  As mentioned above, although embodiment of this invention was described, this embodiment can be suitably changed in the range which does not deviate from the summary of this invention.

  For example, in this embodiment, the increase correction at the time of executing the IG retard is performed at the stage of estimating the engine torque, but this is not performed at the stage of estimating the engine torque, and the clamping pressure in the clamping pressure setting unit 732 is not performed. It may be performed at the setting stage. However, according to this embodiment, the increase correction is performed at the stage of engine torque estimation, and once the estimated engine torque is determined, the clamping pressure can be obtained collectively using the estimated engine torque. Therefore, the control and calculation can be simplified.

In the present embodiment, the estimated engine torque T1 before correction is obtained as T1 = kc−ka · (kb−tg) ² , but is not limited to that obtained using such a quadratic function. . Another function may be used, or it may be obtained by referring to preset map data.

  In this embodiment, the types of IG retard are three types of cold retard, chip retard and knock retard. However, the present invention is not limited to this, and other types of IG retard may be appropriately increased or decreased. May be set.

  In this embodiment, the PCM 700 is provided as a control module that controls the operation of the engine 100 and the operation of the CVT 200 in an integrated manner. Individual control units may also be used.

It is a figure which shows schematic structure of the engine and belt type CVT which concern on this invention. It is a control block diagram of the powertrain control module which controls the drive train containing an engine and CVT. It is a figure which shows the setting characteristic of the amount of IG retards in the case of cold retard. It is a figure explaining the concept of an engine torque estimation method. It is a conceptual diagram of the map data used in order to obtain | require torque correction amount. It is a schematic flowchart of engine torque estimation.

Explanation of symbols

20 belt 21 primary pulley (drive pulley)
31 Secondary pulley (driven pulley)
100 Engine 200 CVT (Belt type CVT)
717 Ignition timing control unit (ignition timing control means)
720 engine torque estimating unit (engine torque estimating means)
T1 Estimated engine torque before correction dT Torque correction amount T2 Estimated engine torque after correction (= T1 + dT)

Claims (6)

In a belt-type CVT clamping pressure control device connected to an engine having an ignition timing control means for retarding an ignition timing when a predetermined ignition timing retard condition is satisfied,
A transmission belt that is hung between a driving pulley and a driven pulley and is clamped by each of the pulleys with a predetermined clamping pressure;
Engine torque estimation means for estimating engine torque from the engine operating state;
Clamping pressure setting means for setting the clamping pressure based on an estimated engine torque value by the engine torque estimating means,
The belt-type CVT pinching pressure control device, wherein the setting value of the pinching pressure is corrected to increase when the ignition timing of the engine is retarded.   2. The belt-type CVT clamping pressure control apparatus according to claim 1, wherein the increase correction of the clamping pressure set value is performed by the engine torque estimating means correcting the increase of the engine torque estimation value.   The belt-type CVT pinching pressure control device according to claim 1 or 2, wherein the increase correction amount of the pinching pressure setting value increases as the engine load during ignition timing retard increases.   4. The belt-type CVT pinching pressure control apparatus according to claim 1, wherein the increase correction amount of the pinching pressure setting value increases as the engine temperature during ignition timing retard decreases.   The ignition timing retard condition is satisfied when at least one of three types of acceleration, cold engine, and knocking is satisfied. 5. A belt-type CVT clamping pressure control device according to any one of 1 to 4.   6. The belt-type CVT pinching pressure control device according to claim 5, wherein an increase correction amount of the pinching pressure set value is a value corresponding to each of the types of ignition timing retards.

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