JP6540086B2 - Control device for four-wheel drive vehicle - Google Patents

Description

  The present invention relates to a control device for a four-wheel drive vehicle provided with a transfer.

  Conventionally, four-wheel drive vehicles are based on two-wheel drive, so-called part-time ones that can be switched to four-wheel drive if necessary, or have a differential (center differential) between the front and rear wheels. There is a so-called full-time type that can travel in a four-wheel drive state (for example, Patent Document 1). Also, four-wheel drive vehicles combining these two systems, and four-wheel drive vehicles equipped with a transfer having a high speed gear (high gear) and a low speed gear (low gear) have been put to practical use.

  In the transfer, switching between the high speed gear and the low speed gear is possible when the condition that the operating position (shift position) of the shift lever is the P range or the N range and the vehicle is stopped is satisfied. When an operation unit (a lever, a switch or the like) for switching the transfer gear is operated by the occupant when this condition is satisfied, an actuator provided for the transfer operates to switch between the high speed gear and the low speed gear.

Unexamined-Japanese-Patent No. 2000-247159

  An automatic transmission incorporating a torque converter and a transmission mechanism is provided between the engine and the transfer. In the automatic transmission, the torque converter transmits the rotation of the engine to the transmission mechanism and increases the torque, and the transmission mechanism reduces the rotational speed of the engine and transmits it to the transfer. When the shift position is in the P range or N range, the automatic transmission opens all the fastening elements so that torque on the engine side (input side) is not transmitted to the transfer side (output side).

  However, since the viscosity is high when the oil of the automatic transmission is low temperature, the torque on the engine side may be transmitted to the transfer side through the oil even if the fastening element is open. That is, even if the shift position is in the P range or N range, torque may act on the transfer gear. Such torque is called drag torque. When the drag torque exceeds the thrust of the above-mentioned actuator, there arises a problem that the transfer gear can not be switched even if the actuator is operated.

  The present invention has been made in view of such problems, and relates to a control device for a four-wheel drive vehicle equipped with a transfer having a high speed gear and a low speed gear, eliminating problems when switching between the high speed gear and the low speed gear. One of the goals is to switch gears smoothly. The present invention is not limited to this object, and is an operation and effect derived from each configuration shown in the embodiments for carrying out the invention to be described later, and it is also another object of the present invention to exert an operation and effect that can not be obtained by the prior art. It can be positioned.

(1) The control device for a four-wheel drive vehicle disclosed herein includes an automatic transmission connected to an engine and having a torque converter and a transmission mechanism, and connected to the automatic transmission and having high speed gear and low speed gear. And a transfer device having a transfer. The control device includes transmission control means for stopping rotation of the input shaft of the transmission mechanism during gear switching between the high speed gear and the low speed gear of the transfer when the shift position is in the non-traveling range. The engine also has a control value for the non-traveling range and a control value for the traveling range, and the shift position is the non-traveling range and the engine uses the control value for the non-traveling range before the gear switching. And engine control means for controlling the engine using the control value for the traveling range during the gear switching even if the shift position is in the non-traveling range .

  The "control value" referred to here is a value possessed by the engine control means (set in the engine control means) in advance, and is for controlling the engine to an optimal state in a predetermined driving state of the vehicle. It is a value. The control value includes the control target when controlling the torque and rotational speed of the engine (for example, the fuel injection amount and injection timing, throttle opening degree, supercharger charging pressure, valve timing and valve lift amount, etc.) Contains the value of). In addition, “a control value for non-traveling range” means that the driving state of the vehicle is “when the shift position is the non-traveling range (P range or N range) and the vehicle speed is zero”. It is a control value. Similarly, "a control value for a traveling range" is a control value when the driving state of the vehicle is "a state where the shift position is a traveling range (D range or R range) and the vehicle speed is zero". It is.

  (2) It is preferable that the control value for the non-traveling range and the control value for the traveling range include a value of a target intake air amount of the engine. In this case, preferably, the engine control means increases the intake air amount of the engine by using the value of the target intake air amount for the travel range during the gear switching. The target intake air amount for the travel range is set to a larger value than the target intake air amount for the non-travel range.

  (3) In this case, the engine control means increases the target intake air amount of the engine stepwise to a value larger than the target intake air amount for the travel range at the start of the gear switching, It is preferable to set to the value of the target intake air amount for the said driving | running | working range after progress of predetermined time from the said start time.

  (4) It is preferable that the control value for the non-traveling range and the control value for the traveling range include the value of the fuel injection amount of the engine. In this case, preferably, the engine control means increases the fuel injection amount of the engine by using the value of the fuel injection amount for the travel range during the gear switching. The value of the fuel injection amount for the traveling range is set to a larger value than the value of the fuel injection amount for the non-traveling range.

(5) It is preferable that the control value for the non-running range and the control value for the running range include the value of the target rotation speed of the engine. In this case, it is preferable that the engine control means lowers the target rotation speed of the engine by using the value of the target rotation speed for the travel range during the gear switching. In addition, the value of the target rotation speed for the travel range is set to a lower value than the value of the target rotation speed for the non-traveling range.
(6) In this case, preferably, the engine control means reduces the target rotation speed of the engine by a predetermined gradient from the start of the gear switching and sets the target rotation speed for the traveling range.

  In the control device of the disclosed four-wheel drive vehicle, the drag torque transmitted to the transfer can be suppressed by stopping the rotation of the input shaft during gear switching, and switching between the high speed gear and the low speed gear can be smoothly performed. It can be carried out. However, when the rotation of the input shaft is stopped, the load acting on the engine increases, and when the rotation of the input shaft is restored, the load acting on the engine decreases. For this reason, the new subject that an engine speed changes is generate | occur | produced.

On the other hand, in the disclosed control device, although the shift position is in the non-traveling range during gear switching, the engine is controlled using the control value for the traveling range. As a result, the engine control corresponding to the increase or decrease of the load of the engine is performed, so that the fluctuation of the engine speed can be suppressed. Since the engine is controlled using the control value for the non-traveling range before the shift position is in the non-traveling range and the high-speed gear and the low-speed gear are switched, the engine rotational speed does not fluctuate.
Therefore, it is possible to switch gears smoothly without any trouble when switching between the high speed gear and the low speed gear of the transfer. Further, since the fluctuation of the engine speed is suppressed, the drive feeling can be improved.

It is a block diagram of a four-wheel drive vehicle by which a control device concerning an embodiment is carried. It is a figure which illustrates the structure of the engine mounted in the vehicle of FIG. 1, and the block configuration of a control apparatus. It is an example of a time chart for explaining control contents of the control device of FIG. 1, (a) is a shift position, (b) is a drive mode, (c) is an ON / OFF state of the first control, (d) is The rotation speed of the input shaft of the transmission mechanism, (e) shows the drag torque, and (f) shows the engine rotation speed when the second control is not performed. It is an example of a time chart for explaining the control contents of the control device of FIG. 1, (a) is the ON / OFF state of the first control, (b) is the ON / OFF state of the second control, (c) is the second (2) indicates the amount of intake air, and (e) indicates the amount of fuel injection in the case of performing the second control. It is an example of a flowchart which shows the control procedure of the control apparatus of FIG.

  A control device of a four-wheel drive vehicle as an embodiment will be described with reference to the drawings. The embodiments shown below are merely illustrative, and there is no intention to exclude the application of various modifications and techniques that are not specified in the following embodiments. The configurations of the present embodiment can be variously modified and implemented without departing from the scope of the present invention, and can be selected as necessary or can be combined as appropriate.

[1. Device configuration]
[1-1. Drive system, braking system]
The control device of the present embodiment is mounted on a vehicle 10 illustrated in FIG. The vehicle 10 is a four-wheel drive vehicle using an engine 20 as a drive source. The vehicle 10 is provided with an engine 20, a transmission 40, a transfer 50, a front differential 11 (hereinafter referred to as a front differential 11), a rear differential 12 (hereinafter referred to as a rear differential 12) and the like as a powertrain.

  The engine 20 of the present embodiment is a multi-cylinder gasoline engine fueled by gasoline. One of the plurality of cylinders provided in the engine 20 is illustrated in FIG. A piston 22 is slidably installed in the cylinder 21, and the reciprocating motion of the piston 22 is converted to rotational motion of the crankshaft 23 via a connecting rod. An intake port 24 and an exhaust port 25 are provided on the top surface of each cylinder 21, and an intake valve 26 and an exhaust valve 27 are provided at the respective port openings. A spark plug 28 is provided between the intake port 24 and the exhaust port 25 in a state in which the tip thereof protrudes toward the combustion chamber. The timing (ignition timing) of ignition at the spark plug 28 is controlled by an engine ECU 2 described later.

  In the intake port 24, an injector 29 for injecting fuel is provided. The amount of fuel injection supplied from the injector 29 into the intake port 24 and the fuel injection timing are controlled by the engine ECU 2. Further, an intake manifold 30 (hereinafter referred to as an intake manifold 30) is provided on the upstream side of the intake air flow from the injector 29. A surge tank 31 for temporarily storing air flowing to the intake port 24 side is provided at an upstream portion of the intake manifold 30.

  A throttle body 32 is connected to the upstream side of the intake manifold 30. An electronic control type throttle valve 33 is incorporated in the throttle body 32 and the amount of air (intake air amount) flowing to the in manifold 30 side is adjusted according to the opening degree of the throttle valve 33 (throttle opening degree). The throttle opening degree (i.e., the intake air amount) is controlled by the engine ECU 2. An intake passage 34 is connected to the further upstream side of the throttle body 32, and an air filter 35 is interposed on the further upstream side of the intake passage 34. As a result, the fresh air filtered by the air filter 35 is supplied to the cylinders 21 of the engine 20 through the intake passage 34 and the intake manifold 30.

  As shown in FIGS. 1 and 2, the torque (output, driving force) of the engine 20 is determined by the front wheel 16F and the rear wheel 16R of the vehicle 10 via the transmission 40 and the transfer 50 connected to the output side of the engine 20. (Hereinafter, these are also referred to as wheels 16). The transmission 40 is an automatic transmission (AT, Automatic Transmission) whose gear ratio is set according to a shift operation by the driver, and has a torque converter 41 and a transmission mechanism 42.

  The torque converter 41 is a power transmission device that increases the torque while transmitting the rotation of the engine 20 to the transmission mechanism 42 through a fluid. The torque converter 41 has a structure in which three impellers, that is, a pump impeller, a turbine liner, and a stator, and a hydraulic fluid (ATF, Automatic Transmission Fluid) are enclosed in the inside of the case. The rotation shaft of the pump impeller (the input shaft of the torque converter 41) is connected to the output shaft of the engine 20, and the rotation shaft of the turbine liner (the output shaft of the torque converter 41) is connected to the transmission mechanism 42 side. Also, the stator is disposed between the face-to-face provided pump impeller and the turbine liner and fixed relative to the case.

  The transmission mechanism 42 is a power transmission device for reducing the rotational speed input from the torque converter 41 and transmitting the reduced rotational speed to the wheels 16. The transmission mechanism 42 has a structure incorporating a fastening element such as a planetary gear mechanism, a clutch and a brake. FIG. 1 illustrates some of the mechanisms and elements incorporated in the transmission mechanism 42. The transmission mechanism 42 according to the present embodiment includes a first clutch 43 that switches connection / disconnection between the input shaft 42a and the output shaft 42b, and a second clutch 44 and a brake 45 disposed closer to the input side than the first clutch 43. Have.

  The first clutch 43 is connected to the input side end of the output shaft 42b, and is provided so as to be able to be fastened to the output side end of the input shaft 42a. The output end of the output shaft 42 b is connected to the input shaft 50 a of the transfer 50, and the input end of the input shaft 42 a is connected to the output shaft of the torque converter 41. When the first clutch 43 is engaged with the input shaft 42a, the rotation of the input shaft 42a is transmitted to the output shaft 42b. On the other hand, when the first clutch 43 releases the input shaft 42a, the rotation of the input shaft 42a is not transmitted to the output shaft 42b.

  The second clutch 44 is provided to be able to be fastened to each of the middle portion of the input shaft 42 a and the brake 45. The brake 45 is fixed to the case. When the second clutch 44 is engaged with both the input shaft 42a and the brake 45, the rotation of the input shaft 42a is stopped. On the other hand, when the second clutch 44 releases at least one of the input shaft 42a and the brake 45, the rotation of the input shaft 42a is not restricted. The transmission mechanism 42 also includes other fastening elements. Each fastening element of the transmission mechanism 42 is controlled by a transmission ECU 1 described later.

  The transmission gear ratio in the transmission mechanism 42 is changed according to the operation position of the shift lever provided in the vehicle compartment (hereinafter referred to as the shift position). In the present embodiment, as shown in FIG. 2, four types of shift positions, “P (parking) range”, “R (reverse) range”, “N (neutral) range”, and “D (drive) range”, are used. The operation position of is set. The P range and the N range are both selected when the vehicle 10 is stopped, and are also referred to as a non-driving range. On the other hand, the D range is also called a travel range. Further, the R range is a range selected when the vehicle 10 travels rearward, and is included in the “traveling range” in the present embodiment.

  As shown in FIG. 1, the transfer 50 is a power distribution device which is connected to the output side of the transmission 40 and distributes the torque of the engine 20 to the front axle 13 and the rear axle 15. The transfer 50 has an intermediate shaft 50b coaxially provided with the input shaft 50a, an output shaft 50c on the rear wheel side to which the torque of the input shaft 50a is transmitted, and a transfer sprocket 50d on the front wheel side. The output shaft 50c is connected to the rear differential 12 via the rear propeller shaft 14R. A pair of left and right rear axles 15 extend from the rear differential 12, and the left and right rear wheels 16R are connected to these rear axles 15, respectively. On the other hand, a front propeller shaft 14F extends from the transfer sprocket 50d, and the front differential 11 is connected to the tip end thereof. A pair of left and right front axles 13 extend from the front differential 11, and the left and right front wheels 16F are connected to the front axles 13, respectively.

  The transfer 50 includes an auxiliary transmission mechanism 51 provided between the input shaft 50a and the intermediate shaft 50b, and a center differential 54 (hereinafter referred to as a center differential 54) provided between the intermediate shaft 50b and the output shaft 50c. Equipped with The transfer 50 further includes a switching mechanism 52 and a lock mechanism 53 provided between the auxiliary transmission mechanism 51 and the center differential 54.

  The auxiliary transmission mechanism 51 is a high / low switching mechanism connected to the output side of the transmission 40, and includes, for example, a plurality of gears, a countershaft, and a coupling sleeve. The auxiliary transmission mechanism 51 has a high speed gear (high gear) and a low speed gear (low gear), and also has an actuator that uses one of the two gears as a power transmission path. The actuator changes the meshing of the elements constituting the auxiliary transmission mechanism 51 to switch gears such that the torque of the engine 20 is transmitted to only one of the high speed gear and the low speed gear. The operation of this actuator is controlled by the transmission ECU 1. When the auxiliary transmission mechanism 51 is set to the high speed gear, the rotation of the input shaft 50a is directly transmitted to the intermediate shaft 50b. On the other hand, when the auxiliary transmission mechanism 51 is set to the low speed gear, the rotation of the input shaft 50a is decelerated and transmitted to the intermediate shaft 50b.

  The center differential 54 absorbs a difference in rotation between the front axle 13 and the rear axle 15 and distributes and transmits torque, and is formed of, for example, a planetary gear mechanism. The switching mechanism 52 switches between two-wheel drive and four-wheel drive, and includes, for example, a plurality of clutch gears connected to the center differential 54 and a coupling sleeve. The lock mechanism 53 locks the differential of the center differential 54, and includes, for example, a plurality of clutch gears connected to the center differential 54 and a coupling sleeve. The states of the switching mechanism 52 and the lock mechanism 53 are controlled by an actuator that operates according to a command from the transmission ECU 1. This actuator may use an actuator for switching the gear of the auxiliary transmission mechanism 51 in combination, or may be provided separately from this.

  The transfer 50 outputs the input from the transmission 40 only to the rear axle 15 when the switching mechanism 52 switches to two-wheel drive. In this state, the vehicle 10 is in a two-wheel (rear wheel) driving state. Hereinafter, the drive mode of the vehicle 10 in this state is referred to as a 2H mode. In the 2H mode, the lock mechanism 53 is inoperative and the differential of the center differential 54 is not locked. Further, when the transfer 50 is switched to four-wheel drive by the switching mechanism 52 in a state where the center differential 54 is not locked, the input from the transmission 40 is the front axle 13 at a ratio according to the gear ratio of the center differential 54, It outputs to the rear axle 15 respectively. In this state, the vehicle 10 is in the four-wheel drive state in which the center differential 54 is opened. Hereinafter, the drive mode of the vehicle 10 in this state is referred to as 4H mode.

  The transfer 50 is in the direct connection state when the center differential 54 is locked by the lock mechanism 53. In this state, the torque from the input shaft 50a is equally distributed to the output shaft 50c and the transfer sprocket 50d without being differentiated by the center differential 54 and transmitted. Hereinafter, the drive mode of the vehicle 10 in this state is referred to as a lock mode. The lock mode includes a high speed lock mode (hereinafter referred to as 4HLc mode) when the sub transmission mechanism 51 is a high speed gear and a low speed lock mode (hereinafter referred to as a 4LLc mode) when the sub transmission mechanism 51 is a low speed gear. There are two types of The switching between the 4HLc mode and the 4LLc mode can be performed when the shift position is the P range or the N range and the vehicle 10 is stopped (for example, at idle time or idle stop time).

  The front differential 11 absorbs the difference in rotation between the left and right front wheels 16F, and divides and transmits torque transmitted from the front propeller shaft 14F to the left and right. The rear differential 12 absorbs the rotational difference between the left and right rear wheels 16R, and divides and transmits torque transmitted from the rear propeller shaft 14R to the left and right. The rear differential 12 includes a differential lock mechanism 12H that locks the differential of the rear differential 12. The diff lock mechanism 12H locks the rear differential 12 by an actuator that operates in accordance with a command from the transmission ECU 1 to establish a direct connection state.

[1-2. Detection system, control system]
As shown in FIG. 2, an operation unit for setting (selecting) a drive mode of the vehicle 10 is provided in a compartment of the vehicle 10, and the switch 3 is attached to the operation unit. The operation unit is, for example, a switch or a lever, and one of the four drive modes (2H mode, 4H mode, 4HLc mode, and 4LLc mode) described above is operated by switching by the occupant (mainly the driver). Set one. The switch 3 outputs a mode signal corresponding to the drive mode set by the operation unit to the transmission ECU 1.

  The vehicle 10 is provided with a gear position sensor 4 that detects the state of the transfer 50. The gear position sensor 4 determines which of the four drive modes the transfer 50 corresponds to, from the positions of the gears of the auxiliary transmission mechanism 51, switching mechanism 52, lock mechanism 53, coupling sleeve, etc. Is detected, and a position signal corresponding to this is output to the transmission ECU 1.

  A shift position sensor 5 is attached to the shift lever. The shift position sensor 5 is a sensor that detects the shift position and outputs a range signal of the corresponding shift range. Here, it is detected in which position of the P range, R range, N range, and D range the shift lever is operated, and the range signal corresponding to each operation position is transmitted to the transmission ECU 1 and the engine ECU 2 respectively. .

  In the vicinity of the crankshaft 23 of the engine 20, an engine speed sensor 6 for detecting the engine speed is provided. The intake passage 34 is provided with an air flow sensor 7 for detecting the amount of intake air. Further, the surge tank 31 is provided with an intake manifold pressure sensor 8 for detecting the pressure of intake air introduced into the cylinder. The intake manifold 30 is also provided with an oxygen concentration sensor for detecting the oxygen concentration in the intake air and an intake air temperature sensor (not shown) for detecting the temperature of the intake air immediately before being introduced into the cylinder. Each information detected by these sensors 6 to 8 is transmitted to the engine ECU 2.

  Further, as shown in FIG. 1 and FIG. 2, the vehicle 10 is provided with wheel speed sensors 9 for detecting the rotation angles of the front axle 13 and the rear axle 15 for each wheel 16. The amount of change per unit time of the rotation angle of each of the front axle 13 and the rear axle 15 is proportional to the number of rotations of each wheel 16, and the number of rotations of each wheel 16 is the wheel speed (vehicle speed) if no slip occurs. Proportional. The information detected by each wheel speed sensor 9 is transmitted to the transmission ECU 1 and the engine ECU 2 respectively.

  As shown in FIG. 2, the vehicle 10 is provided with a transmission ECU 1 and an engine ECU 2 as an electronic control unit (ECU). These electronic control devices are configured as, for example, an LSI device or a built-in electronic device in which a microprocessor, a ROM, a RAM, etc. are integrated, and are communicably connected to each other via a communication line of an in-vehicle network provided in the vehicle 10. . The control device of the four-wheel drive vehicle of the present embodiment is configured to include the transmission ECU 1 and the engine ECU 2. In addition to the transmission ECU 1 and the engine ECU 2, the vehicle 10 is provided with various electronic control devices for controlling devices (in-vehicle devices) mounted on the vehicle 10, such as an air conditioner ECU and an electrical component ECU.

[2. Control configuration]
[2-1. Basic configuration]
The transmission ECU 1 (transmission control means) is an electronic control unit that controls the transmission 40 and the transfer 50 based on information from the switch 3, the gear position sensor 4, the shift position sensor 5 and the like. Specific control targets of the transmission ECU 1 include engagement / release of each fastening element of the transmission mechanism 42 of the transmission 40, the operation of the actuator of the transfer 50, the operation of the actuator of the diff lock mechanism 12H, and the like.

  The transmission ECU 1 controls the transmission mechanism 42 to be in a state corresponding to the shift position based on the range signal input from the shift position sensor 5. Further, based on the mode signal input from the switch 3 and the range signal input from the shift position sensor 5, the transmission ECU 1 controls the transfer 50 to be in a state corresponding to the drive mode. Hereinafter, these two controls are collectively called transmission normal control. For example, when the drive mode is switched from the 2H mode to the 4H mode, the transmission ECU 1 controls the switching mechanism 52 of the transfer 50 to switch to four-wheel drive. When the drive mode is switched from either one of the 4HLc mode and the 4LLc mode to the other, the transmission ECU 1 carries out the first control described later.

  The engine ECU 2 (engine control means) is based on respective information from the rotational speed sensor 6, the air flow sensor 7, the intake pressure sensor 8, etc., and performs a wide range of systems such as an ignition system, fuel system, intake / exhaust system, valve system regarding the engine 20 Is an electronic control unit that comprehensively controls Specific control targets of the engine ECU 2 include an ignition timing by the spark plug 28, a fuel injection amount injected from the injector 29, a fuel injection timing, a throttle opening degree, and the like.

  The engine ECU 2 controls the engine 20 so that the actual engine rotational speed (hereinafter referred to as actual rotational speed) detected by the rotational speed sensor 6 becomes a target value of engine rotational speed (hereinafter referred to as target rotational speed) Do. The target rotational speed is calculated, for example, as an engine rotational speed that satisfies the output request by obtaining an output request for the engine 20 from the depression amount of the accelerator pedal. Alternatively, as described later, using a value set in advance in the engine ECU 2, a value suitable for the operating state is set as the target number of revolutions. The engine ECU 2 changes the actual rotational speed by controlling the throttle valve 33 so as to obtain the throttle opening degree obtained from the depression amount of the accelerator pedal without performing control to set the actual rotational speed to the target rotational speed. You may

  Also, the engine ECU 2 learns the intake air amount using, for example, the deviation of the actual rotation speed from the target rotation speed and the actual intake air amount detected by the air flow sensor 7 (hereinafter referred to as the actual intake air amount). . Alternatively, the engine ECU 2 calculates a target value of the intake air amount (hereinafter referred to as a target intake air amount) so that the actual rotation speed matches the target rotation speed for idle, converts it to a throttle opening corresponding to it, and The valve 33 is controlled, and learning of the calculated target intake air amount is performed. The engine ECU 2 always carries out such control and learning.

  Further, control values for controlling the engine 20 in an optimal state in a predetermined driving state of the vehicle 10 are set in the engine ECU 2 in advance. When the vehicle 10 is in a predetermined driving state, the engine ECU 2 controls the engine 20 using a control value corresponding to the driving state. The control value includes the value of the control target (for example, the fuel injection amount, the fuel injection timing, the throttle opening degree, etc.) when controlling the engine 20. The control values of the present embodiment include the value of the target rotational speed of the engine 20, the value of the target intake air amount, and the value of the fuel injection amount.

  Further, in the engine ECU 2 of the present embodiment, a control value for the non-traveling range and a control value for the traveling range are set. The “control value for non-traveling range” is a control value when the operating state of the vehicle 10 is at least “the non-traveling range (P range or N range) and the vehicle speed is zero”. is there. Similarly, “a control value for a traveling range” is a control value when the operating state of the vehicle 10 is at least “a state where the shift position is a traveling range (D range or R range) and the vehicle speed is zero”. It is. It should be noted that although the control value for making the engine 20 optimal may change if the operating state of the on-vehicle device (for example, air conditioner) of the vehicle 10 is different, the operating state of the on-vehicle device is omitted in this embodiment. I assume.

  That is, when the shift position is the P range or the N range and the vehicle speed is zero, the engine ECU 2 of the present embodiment controls the engine 20 using the control value for the non-traveling range. When the shift position is in the D range or R range and the vehicle speed is zero, the engine ECU 2 controls the engine 20 using the control value for the travel range. Hereinafter, this control is referred to as engine normal control. The engine ECU 2 carries out engine normal control except during execution of the second control described later.

  In this embodiment, when the drive mode of the vehicle 10 is switched from one of the 4HLc mode and the 4LLc mode to the other, that is, when the high-speed gear and the low-speed gear of the transfer 50 are switched, the transmission ECU 1 and the engine ECU 2 The control that is implemented will be described in detail. In the following description, gear switching between the high speed gear and the low speed gear of the transfer 50 is also referred to as high / low switching. In the following description, time charts shown in FIGS. 3 (a) to 3 (f) and 4 (a) to 4 (e) are used as appropriate.

[2-2. Control of transmission (first control)]
First, control performed by the transmission ECU 1 on the transmission 40 will be described. This control is control for eliminating the influence of drag torque that may be generated by the transmission 40 during high-low switching of the transfer 50 (during gear switching). Hereinafter, this control is referred to as first control. When the first control is performed, the above-described transmission normal control is not performed.

  As described above, the transfer 50 can switch between the 4HLc mode and the 4LLc mode when the shift position is the P range or the N range and the vehicle 10 is stopped. That is, when all the fastening elements of transmission 40 are open, torque on the engine side is not transmitted to transfer 50 via the fastening elements, and when the vehicle speed is zero, the high speed gear of auxiliary transmission mechanism 51 and Switching with the low speed gear is performed.

  However, when the hydraulic oil of the transmission 40 is low temperature, the viscosity is high, and even if the fastening element is opened, the torque on the engine side may be transmitted to the transfer 50 via the hydraulic oil. Thus, the torque transmitted to the transfer 50 even when the fastening element is opened is referred to as drag torque. The drag torque increases as the viscosity of the hydraulic fluid increases. When the drag torque exceeds the thrust of the actuator of the transfer 50, high / low switching can not be performed.

  Therefore, the transmission ECU 1 according to the present embodiment performs high-low switching of the transfer 50 after the upstream side of the transfer 50 does not move carelessly. Specifically, the transmission ECU 1 determines the presence / absence of a request for switching between the 4HLc mode and the 4LLc mode based on the mode signal input from the switch 3 and carries out the first control if there is a switching request. In the first control, the second clutch 44 of the transmission mechanism 42 is engaged with both the input shaft 42 a and the brake 45 during high / low switching of the transfer 50 (during the gear switching between the high speed gear and the low speed gear of the sub transmission mechanism 51). It is control to forcibly stop the rotation of the input shaft of the transmission 40 (i.e., the input shaft 42a of the transmission mechanism 42).

  In the determination of the switching request between the 4HLc mode and the 4LLc mode, when the occupant operates the operation unit to switch from either one of the 4HLc mode and the 4LLc mode to the other, it is determined that there is a switching request. That is, it is determined that there is a switching request when there is a switching operation on the operation unit. In the case other than this switching operation, it is determined that there is no switching request. When it is determined that there is no switching request, the transmission ECU 1 performs the above-described transmission normal control without performing the above-described first control.

For example, as shown in FIG. 3 (a) ~ (c) , the shift position at time t _0, which stops at the P range or N range, the driving mode is switched from 4HLc mode to 4LLc mode. Transmission ECU1 determines that this time t ₀ is switching request, starts the high-low switching (and ON the first control) start the first control. In other words, time t ₀ is the starting point of the start point and the first control of the high-low switching.

As shown in FIG. 3 (d) and (e), the rotational speed of the input shaft 42a of the transmission mechanism 42, when the engagement state of the second clutch 44 is strengthened, reduced from time t ₀ at a predetermined gradient (i.e. , The slope changes in the form of a negative linear function), and becomes zero at time t ₁ . Along with this, the drag torque transmitted to the transfer 50 also becomes smaller, and becomes constant below the thrust of the actuator of the auxiliary transmission mechanism 51 indicated by a dashed dotted line in the drawing. That is, by the execution of the first control, the transmission of the drag torque to the transfer 50 is suppressed, and the high / low switching is smoothly performed. Further, the gear noise of the auxiliary transmission mechanism 51 during high / low switching is prevented.

The transmission ECU 1 determines, based on the position signal input from the gear position sensor 4, whether the high / low switching has been completed. When it is determined at time t ₂ and HiLo switching is completed, and ends the first control at this time. Thus, the engagement state is weakened in the second clutch 44, the rotational speed of the input shaft 42a of the transmission mechanism 42 gradually increases from the time t _2, the return to the state prior to performing the first control.

[2-3. Control for engine (second control)]
Next, control that the engine ECU 2 performs on the engine 20 will be described. This control is control for suppressing the fluctuation of the actual rotational speed of the engine 20 by the execution of the first control described above. Hereinafter, this control is referred to as second control. When the second control is performed, the above-described engine normal control is not performed.

  Here, the reason why the actual rotation speed of the engine 20 fluctuates due to the execution of the first control will be described using FIG. 3 (f). In the first control, as described above, the rotation of the input shaft 42a of the transmission mechanism 42 is forcibly stopped. At this time, since the engine 20 is operating, the torque loss in the torque converter 41 increases, and as a result, the load acting on the engine 20 increases. This load increases as the rotational speed of the input shaft 42a decreases, and becomes constant when the input shaft 42a stops.

As shown in FIG. 3 (f), the actual rotational speed of the engine 20 decreases as the load on the engine 20 increases, and becomes lower than the target rotational speed. Here, as described above, the engine ECU 2 controls the engine 20 so that the actual rotation speed becomes the target rotation speed, so that the actual rotation speed decreased due to the first control approaches the target rotation speed It will rise to reach the target number of revolutions eventually. But then, when the time t ₂ the first control is finished, the second clutch 44 is released the input shaft 42a starts to rotate again (rotation of the input shaft 42a is returned). Along with this, the load acting on the engine 20 is reduced, so that the actual rotation number of the engine 20 is blown up this time. As described above, since the load of the engine 20 changes with the execution of the first control, the actual rotation speed also changes.

  Therefore, the engine ECU 2 according to the present embodiment performs the second control so that the actual rotation speed does not change even if the load of the engine 20 changes during high / low switching in which the first control is performed by the transmission ECU 1 Conduct. Specifically, during high / low switching of the transfer 50 (during the gear switching between the high speed gear and the low speed gear of the auxiliary transmission mechanism 51), the engine 20 is controlled using the control value for the travel range. As described above, the control value for the travel range is a control value that is normally used when the shift position is in the D range or R range, but the engine ECU 2 of this embodiment has the shift position in the P range or N range Even during the high / low switching, the engine 20 is controlled using the control value for the travel range.

  This is because the load acting on the engine 20 during the execution of the first control and the load acting on the engine 20 when the shift position is stopped in the D range similarly change. When the shift position is in the D range, the first clutch 43 of the transmission mechanism 42 is engaged, and an engagement element corresponding to the D range is engaged. When the vehicle 10 stops, the wheels 16 stop and the rotation of the output shaft 42b stops. That is, even when the vehicle stops at the D range, the rotation of the input shaft 42a is stopped while the engine 20 is in operation, so that the load acting on the engine 20 fluctuates as in the first control described above. Become.

  The control value for the traveling range is preset so that the engine 20 is in the optimum state (that is, the actual rotation speed does not change) even if the load changes in this manner. Therefore, the engine ECU 2 of the present embodiment switches the engine normal control to the second control (that is, the engine control using the control value for the travel range) during the high / low switching in which the first control is performed. Even if it fluctuates, the actual rotational speed does not fluctuate.

As described above, the control values of the present embodiment include the target rotational speed of the engine 20, the target intake air amount, and the fuel injection amount. Further, in the engine ECU 2, a control value for the non-traveling range and a control value for the traveling range are set. For example, the value Ne _D target RPM for driving range is set to a value lower than the value Ne _N target RPM for the non-driving range. Further, each value F _D of the target intake air amount value Q _D and the fuel injection amount for driving range, the target intake air amount value Q _N and larger than the value F _N of the fuel injection amount for the non-driving range It is set to.

Therefore, engine ECU 2 reduces the target rotational speed of engine 20 by using the above control value for the travel range when switching the gear of transfer 50 when the shift position is the P range or N range, and reduces the actual intake air. Increase the amount and fuel injection amount.
As shown in FIG. 4 (a) ~ (e), the engine ECU2 is in than the time t ₀ when the first control is started before (gear before switching the shift position is a P range or N range), the non The engine 20 is controlled using the control value for the travel range. Then, as shown in FIG. 4 (a) and (b), when the first control is started at time t _0, the engine ECU2 starts a second control for this time t _0, during gearshift travel The engine 20 is controlled using the control value for range.

Specifically, as shown in FIG. 4 (c), it is at the point from the time t ₀ is the start point of the high-low switching reduces the target speed of the engine 20 at a predetermined gradient, has stopped the rotation of the input shaft 42a set to the value Ne _D target rPM for driving range at time t _1. Time t ₁ is the time elapsed for a preset predetermined time from the time t _0. A sensor may be provided to detect the number of rotations of the input shaft 42a, and the time when the number of rotations of the input shaft 42a actually becomes zero may be detected.

Further, as shown in FIG. 4 (e), by increasing the amount of fuel injection from the time t ₀ at a predetermined gradient is set to a value F _D of the fuel injection amount for driving range at time t _1. Engine ECU2 of the present embodiment, each of the target rotational speed and the fuel injection amount from the time t ₂ is the end point of the first control is changed at a predetermined gradient, back to its original value. The target rotational speed and the fuel injection amount may be set in the control value for the driving range at the time of shift from the time t _1.

  Here, the target engine speed and the fuel injection amount are changed at predetermined gradients in order to match the change in the load of the engine 20. The load of the engine 20 does not change at once with the start and end of the first control, but gradually changes with the decrease and increase of the rotational speed of the input shaft 42a. Therefore, by changing the target rotation speed and the fuel injection amount gradually (with a predetermined gradient) in accordance with this change, the fluctuation of the actual rotation speed of the engine 20 during high / low switching is effectively suppressed.

The engine ECU2, as shown by the broken line in FIG. 4 (d), is increased stepwise until a value greater than the value Q _D of the target intake air amount for traveling the target intake air quantity at time t ₀ range, After a predetermined time t _A has elapsed from time t _0, the value is set to the value Q _D of the target intake air amount for the travel range. This takes into consideration the influence of the intake delay. That is, after the high / low switching is started, the actual intake air amount (solid line in the figure) introduced into the cylinder 21 only for a predetermined time t _A from time t ₀ so that the load on the engine 20 will match. inhalation more air than the target intake air quantity Q _D for drive range. The value of the target intake air amount at the predetermined time t _A and the predetermined time t _A is set in advance in consideration of the intake delay.

[3. flowchart]
FIG. 3 is a flowchart illustrating the procedure of the first control and the second control described above, which is repeatedly executed in a predetermined operation cycle.
In step S1, various information is input to the transmission ECU 1 and the engine ECU 2. In step S2, it is determined whether there is a request for switching between the 4HLc mode and the 4LLc mode. If there is a switching request (if there is a switching operation on the operation unit), the process proceeds to step S3. If there is no switching request, the process proceeds to step S9.

  In step S3, a high / low switching instruction is transmitted from the transmission ECU 1 to the actuator of the transfer 50, and the high / low switching is started. In the subsequent step S5, the transmission ECU 1 starts the first control (turns on the first control). Then, in step S6, the second control is started by the engine ECU 2 (the second control is turned ON). As a result, high-low switching is smoothly performed, and fluctuation of the actual rotational speed of the engine 20 is suppressed.

  In step S6, it is determined by the transmission ECU 1 whether the high / low switching has been completed. If high / low switching has not been completed, this flow is returned. In the next cycle, the process proceeds from step S2 to step S9, and it is determined in step S9 whether or not the first control is being performed. In this case, since the first control is performed, the process proceeds to step S6, and the completion determination of the high / low switching is performed. That is, the first control and the second control are performed until the high / low switching is completed. When it is determined in step S6 that the high / low switching has been completed, the process proceeds to step S7, the first control is ended, and in the subsequent step S8, the second control is switched to the engine normal control, and this flow is returned. .

[4. effect]
(1) In the above-described control apparatus for a four-wheel drive vehicle, the drag torque transmitted to the transfer 50 is suppressed by stopping the rotation of the input shaft 42a while switching between the high-speed gear and the low-speed gear of the transfer 50. Can. Thereby, switching between the high speed gear and the low speed gear can be smoothly performed. However, as described above, when the rotation of the input shaft 42a is stopped, the load acting on the engine 20 is increased. Further, when the rotation of the input shaft 42a is restored, the load acting on the engine 20 is reduced. A new problem that the actual number of revolutions of engine 20 fluctuates with the change of load of engine 20 like this occurs.

  On the other hand, in the above-described control device, although the shift position is in the P range or the N range during gear switching, the engine 20 is controlled using the control value for the traveling range. As a result, the engine control corresponding to the increase or decrease of the load of the engine 20 is performed, so that the fluctuation of the actual rotational speed of the engine 20 can be suppressed. Since the engine 20 is controlled using the control value for the non-traveling range before switching between the high-speed gear and the low-speed gear when the shift position is in the P range or N range, the actual rotational speed may be changed Absent.

  Therefore, according to the above-described control device, it is possible to smoothly switch the gears by eliminating problems at the time of switching between the high-speed gear and the low-speed gear of the transfer 50. Further, since the fluctuation of the actual rotational speed of the engine 20 is suppressed, the drive feeling can be improved. In addition, the fluctuation | variation of real rotation speed of the engine 20 in gear switching can be suppressed, and the learning precision of the amount of intake air using real rotation speed can also be raised.

(2) In the above-described control device, the engine ECU2 is, the amount of air actually introduced into the cylinder 21 of the engine 20 by using the value Q _D of the target intake air quantity for drive range during gearshift (actual intake Increase the amount of air). Thereby, it is possible to cope with an increase in the load of the engine 20 during gear switching, and to suppress the fluctuation of the actual rotational speed of the engine 20.

(3) In particular, the above engine ECU2 is increased stepwise up to a value greater than the value Q _D of the target intake air amount the target intake air quantity for drive range at the start of the gear switching, the predetermined time t _A The interval holds this value. Thereby, the actual intake air amount can be changed to correspond to the load fluctuation of the engine 20 by eliminating the influence of the intake delay. As a result, it is possible to effectively suppress the fluctuation of the actual rotational speed of the engine 20 during gear switching.

(4) In the above-described control device, the engine ECU2 is, increase the fuel injection amount of the engine 20 by using the value F _D of the fuel injection amount for driving range during gearshift. Thereby, it is possible to cope with an increase in the load of the engine 20 during gear switching, and to suppress the fluctuation of the actual rotational speed of the engine 20.

(5) In the above-described control device, the engine ECU2 is, reducing the target speed of the engine 20 by using the value Ne _D target RPM for driving range during gearshift. During gear switching, the load on the engine 20 is increased by stopping the rotation of the input shaft 42a, so the actual rotational speed of the engine 20 is reduced. For this reason, the difference between the target rotation number and the actual rotation number can be reduced by reducing the target rotation number using the value of the target rotation number for the travel range during gear switching. As a result, the actual rotation number can be easily converged to the target rotation number, and fluctuation of the actual rotation number can be more effectively suppressed. Although it is necessary to increase the torque to bring the actual rotation speed closer to the target rotation speed, the torque to be increased will be smaller if the difference between the target rotation speed and the actual rotation speed becomes smaller, so the intake air amount And the amount of increase in fuel injection amount can be reduced, and fuel consumption can be improved.

In (6), especially the above-described embodiment, the engine ECU2 is, from the start of the gear-switching reduces the target speed at a predetermined gradient is set to a value Ne _D target RPM for driving range with. Since the load acting on the engine 20 gradually increases from the start of gear switching of the transfer 50, the actual rotational speed of the engine 20 also gradually decreases. By setting the target rotation number in accordance with the change in the actual rotation number, it is possible to more effectively suppress the fluctuation of the actual rotation number of the engine 20 during gear switching.

[5. Other]
As mentioned above, although embodiment of this invention was described, this invention is not limited to said embodiment, It is possible to deform variously in the range which does not deviate from the meaning of this invention.
Although the above-mentioned embodiment explained control of gasoline engine 20 in full detail, this control is applicable also to a diesel engine. Further, in the above-described embodiment, although the case where the means for controlling the engine 20 (engine ECU 2) and the means for controlling the transmission 40 and the transfer 50 (transmission ECU 1) are separate electronic control units is illustrated, One electronic control unit may have these control means as separate functional elements.

The above-described control values (the values Ne _D and _{N N of the} target rotational speed and the values Q _D and Q _{D of the} target intake air amount) are merely examples, and specific values are not limited to those described above. For example, during gear switching, the target rotational speed may use the value for the non-traveling range, and the target intake air amount and the fuel injection amount may use the values for the traveling range as described above. Further, the control value may be set in consideration of the operating state of the on-vehicle device (for example, the air conditioner) of the vehicle 10. In this case, it is possible to make the engine 20 in an optimal state by using a control value that also matches the state of the in-vehicle device.

1 Transmission ECU (transmission control means)
2 Engine ECU (engine control means)
10 vehicles (four-wheel drive)
20 engine 40 transmission (automatic transmission)
41 torque converter 42 speed change mechanism 50 transfer
Target rotation speed value for Ne _D driving range (control value for driving range)
Value of target intake air amount for Q _D drive range (control value for drive range)
Value of fuel injection amount for F _D driving range (control value for driving range)
Target rotational speed value for Ne _N non-driving range (control value for non-driving range)
Q _N Target air intake volume value for non-traveling range (control value for non-traveling range)
Value of fuel injection amount for F _N non-traveling range (control value for non-traveling range)

Claims (6)

A control device for a four-wheel drive vehicle comprising an automatic transmission connected to an engine and having a torque converter and a transmission mechanism, and a transfer connected to the automatic transmission and having a high speed gear and a low speed gear. There,
Transmission control means for stopping the rotation of the input shaft of the transmission mechanism during gear switching between the high-speed gear and the low-speed gear of the transfer when the shift position is in the non-traveling range;
A control value for the non-traveling range and a control value for the traveling range are provided, and the engine is controlled using the control value for the non-traveling range, with the shift position being the non-traveling range and before the gear switching. And engine control means for controlling the engine using the control value for the traveling range during the gear switching even if the shift position is in the non-traveling range. Car control device. The control value for the non-traveling range and the control value for the traveling range include a value of a target intake air amount of the engine,
The four-wheel drive vehicle according to claim 1, wherein the engine control means increases the intake air amount of the engine by using the value of the target intake air amount for the travel range during the gear switching. Control device. The engine control means increases the target intake air amount of the engine stepwise to a value larger than the value of the target intake air amount for the travel range at the start of the gear switching, for a predetermined time from the start time. The control device for a four-wheel drive vehicle according to claim 2, wherein the value is set to a value of the target intake air amount for the travel range after the lapse of time. The control value for the non-traveling range and the control value for the traveling range include the value of the fuel injection amount of the engine,
The engine control means increases the fuel injection amount of the engine by using the value of the fuel injection amount for the traveling range during the gear switching. The control device of the four-wheel drive vehicle according to claim 1. The control value for the non-traveling range and the control value for the traveling range include the value of the target rotation speed of the engine.
The engine control means reduces the target rotational speed of the engine by using the value of the target rotational speed for the travel range during the gear switching. The control device of the four-wheel drive vehicle according to claim 1. The four-wheeled vehicle according to claim 5, wherein the engine control means reduces the target rotational speed by a predetermined gradient from the start of the gear switching to a value of the target rotational speed for the traveling range. Control device of drive car.

Images