EP2913505A1

EP2913505A1 - Vehicular drive apparatus

Info

Publication number: EP2913505A1
Application number: EP13849221.0A
Authority: EP
Inventors: Daisuke Tamaru
Original assignee: Aisin Seiki Co Ltd
Current assignee: Aisin Corp
Priority date: 2012-10-25
Filing date: 2013-09-24
Publication date: 2015-09-02
Also published as: JP2014084814A; BR112015008382A2; EP2913505A4; JP5849929B2; WO2014065062A1; IN2015DN03777A; CN104736823A

Abstract

A vehicular drive apparatus with a manual clutch in which at the start of the vehicle, an excess engine rotation speed increase can be prevented. The vehicular drive apparatus includes a control portion which executes a torque-down control by controlling the engine so that the engine torque becomes the start timing engine torque when the clutch difference rotation speed is equal to or more than a defined difference rotation speed and the engine rotation speed is equal to or more than a first defined rotation speed by calculating the start timing engine torque based on the clutch transmitting torque from the clutch sensor which obtains the clutch transmitting torque generated by the clutch.

Description

[Technical Field]

This invention relates to a vehicular drive apparatus which controls a vehicle starting operation for a vehicle equipped with a manual clutch.

[Background Art]

In an automobile which is equipped with a manual transmission (hereinafter referred to as "MT") and a manual clutch, at the start of the vehicle, an operator of the vehicle depresses the clutch pedal to be in a clutch disconnected state to shift the MT to a first speed stage. Then the operator depresses the acceleration pedal to increase the engine rotation speed and at the same time releases the clutch pedal gradually to be in a clutch connected state thereby transmitting an engine torque to vehicle wheels. Thus, the operator of the vehicle coordinates the depression operation of the acceleration pedal, in other words, an engine outputting (engine rotation speed) and the releasing operation of the clutch pedal, in other words, clutch engagement (engine load) so that a smooth vehicle start can be achieved.
In a Patent Literature 1, a technology is disclosed in which an excess increase of the engine rotation speed at the time of starting can be minimized in a vehicle having the MT and the clutch. According to the technology disclosed therein, the decreasing amount of the torque is calculated based on the engine rotation speed and the vehicle speed and the engine is controlled by a torque obtained by subtracting the decreased torque from the required engine torque based on the acceleration operation of the operator of the vehicle to thereby preventing an excess engine rotation speed increase.

[Citation List]

[Patent Literature]

Patent Literature 1: PCT/JP2007-522378 A

[Summary of Invention]

[Technical Problems]

However, according to the technology disclosed in the Patent Literature 1, since the decreasing amount of torque is calculated based on the engine rotation speed and the vehicle speed, for example, if an operator of the vehicle abruptly depresses the clutch pedal during the torque-down control operation and the clutch transmitting torque is quickly decreased, both the above control and the clutch disengagement operation by the operator of the vehicle are simultaneously performed which may lead to an excessive drop of the engine rotation speed. This will disturb an acceleration of the vehicle and may cause a slow operation behavior of the vehicle.
The present invention was made in consideration with the above problems and the object of the invention is to provide a vehicular drive apparatus for a vehicle equipped with the manual clutch, which can prevent an excess increase of the engine rotation speed and also prevent an unnecessary drop of the engine rotation speed at the time of starting of the vehicle.

[Solution to Problem(s)]

The vehicular drive apparatus associated with the invention of claim 1 to solve the problems includes an engine outputting an engine torque to an output shaft, an engine operating means operated for variably outputting the engine torque from the engine, an input shaft which rotates in association with a rotation of a drive wheel of a vehicle, a clutch provided between the output shaft and the input shaft for controlling a clutch transmitting torque therebetween to be variable, a clutch operating means for operating the clutch to control the clutch transmitting torque to be variable, a clutch transmitting torque obtaining means for obtaining the clutch transmitting torque which is generated by the clutch, a required engine torque calculating means for calculating a required engine torque which is a required torque from the engine based on an operating amount of the acceleration pedal, a start timing engine torque calculating means for calculating a start timing engine torque based on the clutch transmitting torque obtained by the clutch transmitting torque obtaining means and an engine control means for executing a torque-down control by controlling the engine so that the engine torque becomes the start timing engine torque when a clutch difference rotation speed which is a difference rotation speed between the output shaft and the input shaft is equal to or more than a defined difference rotation speed and an engine rotation speed is equal to or more than a first defined rotation speed and executing a normal control by controlling the engine so that the engine torque becomes the required engine torque when the clutch difference rotation speed is less than the defined difference rotation speed.
The invention of claim 2 is characterized in that in claim 1, the vehicular drive apparatus further comprises an engine rotation speed decrease torque calculating means for calculating an engine rotation speed decrease torque which is a minus value torque necessary for decreasing the engine rotation speed, wherein the start timing engine torque calculating means calculates the start timing engine torque adding the engine rotation speed decrease torque.
The invention of claim 3 is characterized in that in claim 1 or 2, the vehicular drive apparatus further comprises a load obtaining means for obtaining a load acting on the engine and a maintaining torque calculating means for calculating a maintaining torque which is a torque necessary for maintaining the engine rotation speed other than the clutch transmitting torque and the engine rotation speed decrease torque based on the load, wherein the start timing engine torque calculating means calculates the start timing engine torque adding the maintaining torque.
The invention of claim 4 is characterized in that in any one of claims 1 through 3, the engine control means controls the engine so that the engine torque becomes the required engine torque when the required engine torque is equal to or less than the start timing engine torque.
The invention of claim 5 is characterized in that in any one of claims 1 through 4, the vehicular drive apparatus further comprises a corrected start timing engine torque calculating means for calculating a corrected start timing engine torque so that the influence of the start timing engine torque becomes more than an influence of the required engine torque, as the engine rotation speed becomes closer to a first defined rotation speed from a second defined rotation speed based on the required engine torque and the start timing engine torque when the engine rotation speed is less than the first defined rotation speed and is equal to or more than the second defined rotation speed which is slower than the first defined rotation speed, wherein the engine control means controls the engine to execute a limited torque-down control so that the engine torque becomes the corrected start timing engine torque when the engine rotation speed is less than the first defined rotation speed and is equal to or more than the second defined rotation speed.
The invention of claim 6 is characterized in that in any one of claims 1 through 5, the clutch transmitting torque obtaining means includes a clutch operating amount detecting means for detecting an operating amount of the clutch operating means.
The invention of claim 7 is characterized in that in any one of claims 2 through 6, wherein the engine rotation speed decrease torque calculating means calculates the engine rotation speed decrease torque to be zero when a current engine rotation speed is slower than a target engine rotation speed which is a rotation speed of the engine to be a target upon decreasing the engine rotation speed and calculates an absolute value of the engine rotation speed decrease torque such that the faster the current engine rotation speed is than the target engine rotation speed, the larger the absolute value of the engine rotation speed decrease torque becomes.
The invention of claim 8 is characterized in that in any one of claims 1 through 7, the vehicular drive apparatus further includes a vehicle speed detecting means for detecting a vehicle speed of the vehicle and the engine control means executes the normal control when the vehicle speed detected by the vehicle speed detecting means is faster than a predetermined speed.

[Advantageous effects of invention]

According to the invention associated with claim 1, the start timing engine torque calculating means calculates the start timing engine torque based on the clutch transmitting torque. The engine control means controls the engine so that the engine torque becomes the start timing engine torque when the clutch is under half clutch state where the clutch difference rotation speed is equal to or more than a defined difference rotation speed, and the engine rotation speed is equal to or more than a first defined rotation speed.
Thus, upon the start of the vehicle under the half clutch state, the engine is controlled so that the engine torque becomes the start timing engine torque calculated according to the clutch transmitting torque when the engine rotation speed is equal to or more than the first defined rotation speed. Accordingly, the start timing engine torque is decreased before the increase of the engine rotation speed which is caused by the decrease of the clutch transmitting torque when the engine rotation speed is equal to or more than the first defined rotation speed. This can prevent the excess increase of the engine rotation speed. On the other hand, when the start timing engine torque decrease by the control and the clutch transmitting torque decrease by the operation by the operator are performed at the same time, it is possible to quickly reflect the result of the clutch transmitting torque decrease on the start timing engine torque thereby to prevent an unnecessary drop of the engine rotation speed. In other words, according to the invention the excess engine rotation speed increase can be prevented and unnecessary drop of the engine rotation speed can be prevented.
According to the invention associated with claim 2, the engine rotation speed decrease torque calculating means calculates the engine rotation speed decrease torque. Further, the start timing engine torque calculating means calculates the start timing engine torque by adding the engine rotation speed decrease torque.
Thus, the start timing engine torque smaller by the engine rotation speed decrease torque which decreases the engine rotation speed under the torque-down control operation is calculated. Accordingly, the engine rotation speed can be decreased when the engine rotation speed is equal to or more than the first defined rotation speed thereby to further surely prevent an excess increase of the engine rotation speed.
According to the invention associated with claim 3, the maintaining torque calculating means calculates the maintaining torque based on the load acting on the engine and the start timing engine torque calculating means calculates the start timing engine torque by adding the maintaining torque.
Therefore, for instance, when the auxiliary machine driven by the engine is stopped and the load of the engine is decreased, the start timing engine torque to which the decrease of the load is added is calculated. Thus the excess increase of the engine rotation speed and unnecessary drop of the engine rotation speed can be further surely prevented.
According to the invention associated with claim 4, the engine control means controls the engine so that the engine torque becomes the required engine torque when the required engine torque is equal to or less than the start timing engine torque.
Thus, when the required engine torque is equal to or less than the start timing engine torque, the engine is controlled to output the required engine torque which reflects the intension of the operator of the vehicle. Thus the engine torque is not deviated from the intension of the operator of the vehicle to prevent the unpleasant feeling of the operator and at the same time an unnecessary increase of the engine rotation speed.
According to the invention associated with claim 5, the corrected start timing engine torque calculating means calculates the corrected start timing engine torque so that the influence of the start timing engine torque becomes more than an influence of the required engine torque, as the engine rotation speed becomes closer to the first defined rotation speed from the first defined rotation speed based on the required engine torque and the start timing engine torque when the engine rotation speed is less than the first defined rotation speed and is equal to or more than the second defined rotation speed. The engine control means controls the engine to execute a limited torque-down control so that the engine torque becomes the corrected start timing engine torque.
Thus, upon starting of the vehicle, when the engine rotation speed is gradually increased, the control is transited from the normal control to the torque-down control through the limited torque-down control where the influence of the torque-down is gradually increased. Accordingly, a sudden engine torque change can be avoided to prevent giving an unpleasant feeling to the operator of the vehicle during the torque-down control operation.
According to the invention associated with claim 6, the clutch transmitting torque obtaining means includes a clutch operating amount detecting means which detects the operating amount of the clutch operating means. Therefore, the operating amount of the clutch operating means can be obtained by using a simple structure.
According to the invention associated with claim 7, the engine rotation speed decrease torque calculating means calculates engine rotation speed decrease torque to be zero (0) when the current engine rotation speed is slower than the target engine rotation speed. Thus, the excess drop of the engine rotation speed can be prevented and an unpleasant feeling by the operator can be avoided and at the same time engine stall can be also prevented.
Further, the engine rotation speed decrease torque calculating means calculates the absolute value of the engine rotation speed decrease torque such that the faster the current engine rotation speed than the target engine rotation speed is, the larger the absolute value of the engine rotation speed decrease torque becomes. Therefore, the more the current engine rotation speed increases to deviate from the target engine rotation speed, the larger the absolute value of the engine rotation speed decrease torque is calculated. Thus, the engine rotation speed which becomes faster than the target engine rotation speed can be surely decreased to the target engine rotation speed to thereby prevent the excess increase of the engine rotation speed.
According to the invention associated with claim 8, the engine control means executes the normal control when the vehicle speed detected by the vehicle speed detecting means is faster than the predetermined speed.
Thus, when the vehicle speed is faster than the predetermined speed, the torque-down control or the limited torque-down control is not executed. Therefore, even when the driver of the vehicle had operated the clutch to be the half clutch state after the start of the vehicle, the torque-down control or the limited torque-down control is not executed to give no uncomfortable feeling to the driver of the vehicle.

[Brief Explanation of Attached Drawings]

[Fig. 1 Fig. 1 is a schematic structural view of a vehicular drive apparatus according to an embodiment of the invention;
[Fig. 2] Fig. 2 illustrates a clutch transmitting torque mapping data representing a relationship between the clutch stroke and the clutch transmitting torque;
[Fig. 3] Fig. 3 is a graph illustrating an outline of the embodiment, wherein the horizontal axis indicates elapsed time and the vertical axis indicates engine rotation speed, engine torque, clutch transmitting torque and acceleration opening degree;
[Fig. 4] Fig. 4 is a flowchart of clutch/engine cooperative control;
[Fig. 5] Fig. 5 illustrates a flowchart of the torque-down control which is a sub-routine of the clutch/engine cooperative control of Fig. 4;
[Fig. 6] Fig. 6 is an example of an engine rotation speed decrease torque calculating data which is a mapping data representing the relationship between the difference rotation speed between the target engine rotation speed Net and the current engine rotation speed Ne and the engine rotation speed decrease torque Ten;
[Fig. 7] Fig. 7 is a flowchart of maintaining torque calculating process which is a sub-routine of the torque-down control in Fig. 5; and
[Fig. 8] Fig. 8 illustrates an example of a compressor auxiliary machine torque calculating data which is a mapping data representing the relationship between the engine rotation speed Ne and the compressor auxiliary machine torque Tac.
[Fig. 9] Fig. 9 is a flowchart of limited torque-down control which is a sub-routine of the clutch/engine cooperative control in Fig. 4; and
[Fig. 10] Fig. 10 is a table explaining the vehicle state when the vehicle starts.

[Embodiments for Implementing Invention]

(Explanation of vehicle)

The vehicular drive apparatus 1 according to the embodiment of the invention will be explained with reference to Fig. 1. Fig. 1 illustrates an structure of the vehicular drive apparatus 1 equipped with an engine 2. In Fig. 1, the bold lines indicate mechanical connection between the devices and arrows by broken lines indicate signal lines for controlling.
As shown in Fig. 1, the vehicle is equipped with the engine 2, a clutch 3, a manual transmission 4 and a differential device 17, in series in this order of arrangement. The differential device 17 is connected to drive wheels 18R and 18L of the vehicle. The drive wheels 18R and 18L indicate either front, rear or front/rear wheels of the vehicle.
The vehicle includes an acceleration pedal 51, a clutch pedal 53 and a brake pedal 56. The acceleration pedal 51 is operated to variably change the engine torque Te outputted from the engine 2. The acceleration pedal 51 is provided with an acceleration sensor 52 which detects the acceleration opening degree Ac which corresponds to an operating amount of the acceleration pedal 51.
The clutch pedal 53 operates the clutch 3 to be in a disconnected state and in a connected state and is operated to variably change the clutch transmitting torque, which will be explained later. The vehicle further includes a master cylinder 55 which generates a hydraulic pressure corresponding to the operating amount of the clutch pedal 53. The master cylinder 55 is provided with a clutch sensor 54 which detects a stroke of the master cylinder 55.
The brake pedal 56 is provided with a brake sensor 57 which detects an operating amount of the brake pedal 56. The vehicle includes a brake master cylinder (not shown) which generates a hydraulic pressure responding to the operating amount of the brake pedal 56 and a brake device 19 which applies the wheels of the vehicle with a braking force according to the master pressure generated by the brake master cylinder.
The engine 2 is such as a gasoline engine or a diesel engine using hydrocarbon system fuel, such as gasoline or light oil. The engine 2 includes an output shaft 21, a throttle valve 22, an engine rotation speed sensor 23, an oil temperature sensor 25 and a fuel injection device 28. The output shaft 21 is rotated unitary with a crank shaft which is rotatably driven by a piston. Thus, the engine 2 outputs the engine torque Te to the output shaft 21. It is noted that when the gasoline engine is used as the engine 2, an ignition device (not shown) is provided on a cylinder head of the engine 2 for igniting an air-fuel mixture gas in the cylinder.
The throttle valve 22 is provided in a pathway which supplies the cylinder of the engine 2 with the air. The throttle valve 22 is used for adjusting the supplied air amount in the cylinder of the engine 2. The fuel injection device 28 is provided at a pathway which supplies inside of the engine 2 with the air or at the cylinder head of the engine 2. The fuel injection device 28 is used for injecting the fuel such as gasoline or the light oil.
The engine rotation speed sensor 23 is provided in the vicinity of the output shaft 21. The engine rotation speed sensor 23 detects the engine rotation speed Ne which corresponds to the rotation speed of the output shaft 21 and outputs the detected signal to a control portion 10. The oil temperature sensor 25 detects the oil temperature "t" of the engine oil used for lubricating the engine 2. The detected signal is outputted to the control portion 10. It is noted here that in this embodiment, the output shaft 21 of the engine 2 is connected to a flywheel 31 which is an input member of the clutch 3 which will be explained later.
The output shaft 21 or a shaft or a gear rotated in association with the output shaft 21 is connected to a generator 26 and a compressor 27a of an air-conditioner 27. The generator 26 generates the electric power necessary for the vehicle.
The cutch 3 is provided between the output shaft 21 of the engine 2 and a transmission input shaft 41 of the manual transmission 4 which will be explained later. The clutch 3 is a manually operated type clutch which connects or disconnects the output shaft 21 and the transmission input shaft 41 by the operation of the clutch pedal 53 by an operator of the vehicle and at the same time variably changes the clutch transmitting torque Tc (See Fig. 2) between the output shaft 21 and the transmission input shaft 41. The clutch 3 includes the flywheel 31, a clutch disc 32, a clutch cover 33, a diaphragm spring 34, a pressure plate 35, a clutch shaft 36, a release bearing 37 and a slave cylinder 38.
The flywheel 31 is of a disc plate shape and is connected to the output shaft 21. The clutch shaft 36 is connected to the transmission input shaft 41. The clutch disc 32 is of a disc plate shape and is provided with a friction material 32a at the outer peripheral surfaces of both sides of the clutch disc 32. The clutch disc 32 faces with the flywheel 31 and is in spline connection with the clutch shaft 36 at the tip end thereof allowing slidable movement in an axial direction but restricting rotation relative to the clutch shaft 36.
The clutch cover 33 is formed by a flattened cylindrical shaped cylindrical portion 33a and a plate portion 33b extending in a rotation center direction from one end of the cylindrical portion 33a. The other end of the cylindrical portion 33a is connected to the flywheel 31. Therefore, the clutch cover 33 is rotated together with the flywheel 31. The pressure plate 35 is of a disc shape having a hole at the center thereof. The pressure plate 35 is provided at the opposite side of the flywheel 31 and facing to the cutch disc 32 and is slidably movable in an axial direction. The clutch shaft 36 is inserted into the pressure plate 35 at the central portion thereof.
The diaphragm spring 34 is formed by a ring shaped ring portion 34a and a plurality of plate spring portions 34b which is extending toward inside from an inner peripheral brim of the ring portion 34a. The plate spring portions 34b are gradually inclined towards the inside so as to be positioned on the plate portion 33b side. The plate spring portions 34b are elastically deformable in an axis line direction. The diaphragm spring 34 is disposed between the pressure plate 35 and the plate portion 33b of the clutch cover 33 under being compressed state in an axial direction. The ring portion 34a is in contact with the pressure plate 35. The center portion of the plate spring portion 34b is connected to the inner peripheral brim of the plate portion 33b. The clutch shaft 36 is inserted into the central portion of the diaphragm spring 34.
The release bearing 37 is attached on a housing (not shown) of the clutch 3. The clutch shaft 36 is inserted into the central portion of the release bearing 37 and is slidably movable in an axial direction. The release bearing is provided with a first member 37a and a second member 37b which are oppositely provided and relatively rotatable. The first member 37a is in contact with the tip end of the plate portion 33b.
The slave cylinder 38 includes a push rod 38a which advances and retreats by the hydraulic pressure. The tip end of the push rod 38a is in contact with the second member 37b of the release bearing 37. The slave cylinder 38 and the master cylinder 55 are connected with each other by a hydraulic pressure conduit 58.
Under the clutch pedal 53 being not depressed, no hydraulic pressure is generated at the master cylinder 55 and the slave cylinder 38. Under this state, the clutch disc 32 is biased towards the flywheel 31 pushed thereto by the diaphragm spring 34 via the pressure plate 35. Accordingly, the flywheel 31, the clutch disc 32 and the pressure plate 35 are integrally rotated by the friction force generated between the friction material 32a and the flywheel 31 and the friction force generated between the friction material 32a and the pressure plate 35. Thus, the output shaft 21 and the transmission input shaft 41 are connected for unitary rotation.
On the other hand, when the clutch pedal is depressed, hydraulic pressure is generated in the master cylinder 55 and then also generated in the slave cylinder 38. By this hydraulic pressure, the push rod 38a of the slave cylinder 38 pushes the release bearing 37 towards the diaphragm spring 34 side. Then the plate spring portion 34b is deformed at a connecting portion thereof with the inner peripheral brim of the plate portion 33b as a fulcrum point. Then the biasing force for biasing the clutch disc 32 to the flywheel 31 becomes weak and finally becomes zero.
As shown in Fig. 2, as the clutch stroke which corresponds to the stroke of the master cylinder 55 increases, the clutch transmitting torque Tc which is transmitted by the clutch 3 from the output shaft 21 to the transmission input shaft 41 becomes small and when the biasing force above becomes zero, the clutch transmitting torque Tc becomes zero and the clutch 3 become in fully disconnected state. Thus as explained, the clutch 3 according to the embodiment is a normally closed type clutch, in which the clutch 3 is in connected state when the clutch pedal 53 is not depressed.
The manual transmission 4 is a stepped stage transmission wherein a plurality of speed stages respectively having different gear ratios is selectively shifted over between the transmission input shaft 41 and a transmission output shaft 42. A plurality of idle gears (not shown) which is idly rotatable relative to the axis and a plurality of fixed gears (not shown) engaging with the idle gears, whose idle rotation relative to the axis is restricted, are attached to either one of the transmission input shaft 41 and the transmission output shaft 42.
Further, the manual transmission 4 is provided with a select mechanism wherein one of the plurality of idle gears is selected and the selected gear is restricted relative rotation to the shaft on which the selected gear is fitted. By this structure, the transmission input shaft 41 is rotated in association with the drive wheels 18R and 18L. Further, the manual transmission 4 is provided with a shift operation mechanism (not shown) in which the operation of the shift lever 45 by the operator of the vehicle is converted into a force for operating the select mechanism.
A transmission input shaft rotation speed sensor 43 is provided in the vicinity of the transmission input shaft 41 for detecting the rotation speed of the transmission input shaft 41 (transmission input shaft rotation speed Ni). The transmission input shaft rotation speed Ni (clutch rotation speed Nc) detected by the transmission input shaft rotation speed sensor 43 is outputted to the control portion 10.
A transmission output shaft rotation speed sensor 46 is provided in the vicinity of the transmission output shaft 42 for detecting the rotation speed of the transmission output shaft 42 (transmission output shaft rotation speed No). The transmission output shaft rotation speed No detected by the transmission output shaft rotation speed sensor 46 is outputted to the control portion 10.
The control portion 10 controls the vehicle as a whole and has a memory portion which is formed by a CPU, RAM, ROM and a memory device formed by a nonvolatile memory (these are not shown). The CPU executes the programs corresponding to the flowcharts indicated in Figs. 4, 5, 7 and 9. The RAM memorizes temporarily the variables which are necessary for executing the programs. The memory portion memorizes the above programs, mapping data shown in Figs.2, 6 and 8.
The control portion 10 calculates the required engine torque Ter which corresponds to the engine torque required by an operator of the vehicle based on the acceleration opening degree Ac detected by the acceleration sensor 52 according to the operation of the acceleration pedal 51 by the operator of the vehicle. Then based on the required engine torque Ter, the control portion 10 adjusts the opening degree S of the throttle valve 22 to adjust the suction amount of the air and the fuel injection amount of the fuel injection device 28, and further controls the ignition device.
By this, the supply amount of the air-fuel mixture including the fuel is adjusted and the engine torque Te outputted from the engine 2 is adjusted to be the required engine torque Ter and at the same time the engine rotation speed Ne is adjusted. It is noted here that when the acceleration pedal 51 is not depressed (acceleration opening degree Ac is zero), the engine rotation speed Ne is kept to be the idle rotation speed (for example 700 r.p.m.).
The control portion 10 calculates the clutch transmitting torque Tc that is the amount that the clutch can transmit to the transmission input shaft 41 from the output shaft 21 by referencing the clutch stroke Cl detected by the clutch sensor 54 to the clutch transmitting torque mapping data which represents the relationship between the clutch stroke Cl and the clutch transmitting torque Tc illustrated in Fig. 2.
The control portion 10 calculates the vehicle speed V based on the transmission output shaft rotation speed No detected by the transmission output shaft rotation speed sensor 46. The control portion 10 calculates the clutch difference rotation speed Δc which corresponds to the difference rotation speed of the clutch 3by subtracting the transmission input shaft rotation speed Ni detected by the transmission input shaft rotation speed sensor 43 from the engine rotation speed Ne detected by the engine rotation speed sensor 23. In other words, the clutch difference rotation speed Δc is the difference rotation speed of the clutch 3, i.e., the difference rotation speed between the output shaft 21 and the transmission input shaft 41.
The vehicular drive apparatus 1 according to the embodiment is a structure which includes the engine 2, clutch 3, manual transmission 4, control portion 10, clutch pedal 53, clutch sensor 54, master cylinder 55, acceleration pedal 51, acceleration sensor 52, brake pedal 56, brake sensor 57 and hydraulic pressure conduit 58.

(Outline of the embodiment)

The outline of the embodiment of the invention will be explained with reference to Fig. 3. When the vehicle speed V is equal to or less than a predetermined speed and the brake pedal 56 is not depressed, and the clutch difference rotation speed Δc is equal to or more than a predetermined speed, in other words, under the condition that the vehicle is in starting state and the clutch is in half clutch state, when the engine rotation speed Ne is equal to or more than a first defined rotation speed N1, the torque-down control is executed.
The torque-down control is a control where the engine torque Te as shown with a bold line in Fig. 3 is decreased ("1" in Fig. 3) in comparison with the engine torque Te (torque illustrated with a dot chain line in Fig. 3) according to the required engine torque Ter calculated based on the operation of the acceleration pedal 51 by the operator of the vehicle. Thus, by executing the torque-down control, a sudden increase of the engine rotation speed due to a half clutch operation can be prevented.
More specifically, the control portion 10 under the starting state of the vehicle, different from the other states of the vehicle, calculates the start timing engine torque Tes1 based on the formula (1) below. The control portion 10 controls the engine 2 so that the engine torque Te becomes the stat timing engine torque Tes1. $Tes 1 = Tc + Ten + Tk$

Tes1: Start timing engine torque:
Tc: Clutch transmitting torque:
Ten: Engine rotation speed decrease torque (minus value)
Tk: Maintaining torque.

It is noted that the engine rotation speed decrease torque Ten means a minus (negative) torque which is necessary to decrease the rotation speed of the engine 2 to the target engine rotation speed Net. The maintaining torque Tk means a torque necessary to maintain the target engine rotation speed Net other than the clutch transmitting torque Tc and the engine rotation speed decrease torque Ten, while the torque-down control and the limited torque-down control which will be explained later are executed. This torque is calculated based on a load or the like by an auxiliary machine connected to the output shaft 21 of the engine 2.
When the clutch pedal 53 is rapidly depressed to rapidly decrease the clutch transmitting torque Tc, the start timing engine torque Tes1 is also decreased as the decrease of the clutch transmitting torque Tc. In other words, according to the embodiment, when the clutch transmitting torque Tc decreases, the start timing engine torque Tes1 decreases before the rising of the engine rotation speed Ne (1 in Fig. 3). Thus, unnecessary increase of the engine rotation speed Ne can be prevented. This will be explained further in detail according to the flowchart shown in Fig. 4.

(Clutch/Engine cooperative control)

The clutch/engine cooperative control is explained hereinafter using the flowchart in Fig. 4. When an ignition key of the vehicle is NO and the engine 2 is started, the clutch/engine cooperative control starts and the program goes to the step S11.
At the step S11, when the control portion 10 judges that the brake pedal 56 is not depressed and the brake device 19 does not generate the braking force (Brake OFF) (S11; YES) based on the detection signal from the brake sensor 57, the control portion 10 advances the program to the step S12. On the other hand, when the control portion 10 judges that the brake pedal 56 is depressed and the brake device 19 generates the braking force (Brake ON), (S11; NO), the control portion 10 advances the program to the step S18.
At the step S12, when the control portion 10 judges that the clutch transmitting torque Tc is not zero (clutch 3 is not completely disconnected) based on the detection signal from the clutch sensor 54 (S12; YES), the control portion 10 advances the program to the step S13. On the other hand, when the control portion 10 judges that the clutch transmitting torque Tc is zero (clutch 3 is completely disconnected) (S12; NO), the control portion 10 advances the program to the step S18.
At the step S13, when the control portion 10 judges that the vehicle speed V is equal to or less than a predetermined speed (such as for example, 20 km/h) (S13; YES), the control portion 10 advances the program to the step S14 and the control portion 10 judges that the vehicle speed V is faster than the predetermined speed (S13; NO), the control portion 10 advances the program to the step S18.
At the step S14, when the control portion 10 judges that the clutch difference rotation speed Δc is equal to or more than a first defined difference rotation speed A (for example, 500 r.p.m.) based on the detection signal outputted from the engine rotation speed sensor 23 and the transmission input shaft rotation speed sensor 43 (S14; YES), the control portion 10 advances the program to the step S15. Further, when the control portion 10 judges that the clutch difference rotation speed Δc is less than the defined difference rotation speed A (S14; NO), the control portion 10 advances the program to the step S18.
At the step S15, when the control portion 10 judges that the engine rotation speed Ne is equal to or more than a first defined rotation speed N1 (for example 2500rpm), the control portion 10 advances the program to the step S16. Further, when the control portion 10 judges that the engine rotation speed Ne is less than the first defined rotation speed N1 and equal to or more than the second defined rotation speed N2, the control portion 10 advances the program to the step S17. Still further, when the control portion judges that the engine rotation speed Ne is less than the second defined rotation speed N2, the program goes to the step S18. It is noted here that the second defined rotation speed N2 is set to be slower than the first defined rotation speed N1.
At the step S16, the control portion 10 executes the torque-down control. This torque-down control will be explained with reference to the flowchart shown in Fig. 5. After the process of the step S16 finished, the program returns to the step S11.
At the step S17, the control portion 10 executes the limited torque-down control. This limited torque-down control will be explained with reference to the flowchart shown in Fig. 9. After the process of the step S17 finished, the program returns to the step S11.
At the step S18, the control portion 10 finishes either one of the controls of the torque-down control and the limited torque-down control which has been started. Then the control portion 10 executes the normal engine control. In other words, the control portion 10 controls the engine 2 so that the engine torque Te becomes the required engine torque Ter calculated based on the operation of the acceleration pedal 51 by the operator of the vehicle. After the process of the step S18 finished, the program returns to the step S11.

(Torque-down control)

The torque-down control will be explained hereinafter with reference to the flowchart in Fig. 5. When the torque-down control starts, the program goes to the step S16-1.
At the step S16-1, the control portion 10 calculates the clutch transmitting torque Tc by referencing the clutch stroke Cl detected by the clutch sensor 54 to the clutch transmitting torque mapping data shown in Fig. 2. After the process of the step S16-1 finished, the program goes to the step S16-2.
At the step S16-2, the control portion 10 calculates the engine rotation speed decrease torque Ten. More specifically, the control portion 10 calculate the engine rotation speed decrease torque Ten by referencing the engine difference rotation speed which is obtained by subtracting the current engine rotation speed Ne from the target engine rotation speed Net to the engine rotation speed decrease torque calculating data as shown in Fig. 6. It is noted that in this embodiment, the target engine rotation speed Net is set to be the first defined rotation speed N1.
It is noted here that when the value obtained by subtracting the current engine rotation speed Ne from the target engine rotation speed Net is a plus value (positive value), in other words, when the current engine rotation speed Ne is slower than the target engine rotation speed Net, the engine rotation speed decrease torque Ten is set to be zero (0). Further, the larger the absolute value obtained by subtracting the engine rotation speed decrease torque Ten from the target engine rotation speed Net is, i.e., the faster the current engine rotation speed Ne is than the target engine rotation speed Net, the larger the absolute value of the engine rotation speed decrease torque Ten is set.
When the above explained engine difference rotation speed is between the difference rotation speeds defined by the engine rotation speed decrease torque calculating data shown in Fig. 6, a linear interpolation is performed on the target engine rotation speeds corresponding to the difference rotation speeds neighboring to the current engine difference rotation speed at both sides thereof to thereby calculating the engine rotation speed decrease torque Ten. After the process of the step S16-2, the program goes to the step S16-3.
At the step S16-3, the control portion 10 calculates the maintaining torque Tk. The maintaining torque Tk means a torque necessary for maintaining the target engine rotation speed Net other than the clutch transmitting torque Tc and the engine rotation speed decrease torque Ten. The calculation of the maintaining torque is explained using the flowchart of the maintaining torque calculation process as shown in Fig. 7.
When the maintaining torque calculation process starts, the program goes to the step S31. At the step S31, the control portion 10 calculates the engine friction torque Tef based on the current oil temperature "t" and the current engine rotation speed Ne. After the process of the step S31, the program goes to the step S32.
At the step S32, the control portion 10 calculates the auxiliary machine torque Ta. The auxiliary machine torque Ta is a torque necessary for driving an auxiliary machine which is connected to the output shaft 21 of the engine 2 and is represents the total torque of the friction torque and the inertia torque of the auxiliary machine. A method for calculating a compressor auxiliary machine torque Tac of a compressor 27a of an air-conditioner 27 will be explained hereinafter as an example of an auxiliary machine. The control portion 10 calculates the compressor auxiliary machine torque Tac by referencing the current engine rotation speed Ne to the "compressor auxiliary machine torque calculating data" shown in Fig. 8 which represents the relationship between the engine rotation speed and the compressor auxiliary machine torque.
It is noted that the compressor auxiliary machine torque Tac is set to be greater as the engine rotation speed Ne becomes faster. Further, the compressor auxiliary machine torque Tac is largely set where the air-conditioner is ON, as compared to the case where the air-conditioner is OFF. The compressor auxiliary machine torque Tac is calculated by performing a linear interpolation on the compressor auxiliary machine torques corresponding to the engine rotation speeds neighboring to the current engine rotation speed Ne at both sides thereof, when the current engine rotation speed Ne is between the engine rotation speeds defined in the compressor auxiliary machine torque calculating data indicated in Fig. 8.
Similar to the calculating method as that for the compressor auxiliary torque Tac, the control portion 10 calculates a generator auxiliary torque Tag of the generator 26 which is another example of the auxiliary machines and an auxiliary machine torque of the auxiliary machine connected to the output shaft 21 of the engine 2. The control portion 10 calculates the auxiliary machine torque Ta by summing up the compressor auxiliary machine torque Tac and the generator auxiliary machine torque Tag and so on. After the process of the step S32, the program goes to the step S33.
At the step S33, the control portion 10 calculates the adjusting torque "α". The adjusting torque α is a necessary torque other than the engine friction torque Tef and the auxiliary machine torque Ta and is calculated based on the information regarding the engine rotation speed Ne and the like. After the process of the step S33, the program goes to the step S34.
At the step S34, the control portion 10 calculates the maintaining torque Tk based on the following formula (2). $Tk = Tef + Ta + Tα$

Tk.....Maintaining torque
Tef....Engine friction torque
Ta.....Auxiliary machine torque
Tα.....Adjusting torque

After the process of the step S34, the process at the step S16-3 in Fig. 5 ends and the program goes to the step S16-4.
At the step S16-4, the control portion 10 calculates the start timing engine torque Tes1 based on the formula (1) above. After the process of the step S116-4, the program goes to the step S16-5.
At the step S16-5, when the control portion 10 judges that the start timing engine torque Tes1 is smaller than the required engine torque Ter (S16-5; YES), the program goes to the step S16-6 and when the control portion 10 judges that the start timing engine torque Tes1 is equal to or more than the required engine torque Ter (S16-5; NO), the program goes to the step S16-7.
At the step S16-6, the control portion 10 controls the throttle valve 22, fuel injection device 28 and the ignition device so that the engine torque Te which the engine 2 generates becomes the start timing engine torque Tes1 calculated at the step S16-4. After the process of the step S16-6, the program returns to the step S11 in Fig. 4.
At the step S16-7, the control portion 10 controls the throttle valve 22, fuel injection device 28 and the ignition device so that the engine torque Te which the engine 2 generates becomes the required engine torque Ter. After the process of the step S16-8, the program returns to the step S11 in Fig.4.

(Limited torque-down control)

The limited torque-down control will be explained hereinafter with reference to the flowchart shown in Fig. 9. When the limited torque-down control starts, the program goes to the step S17-1.
At the step S17-1, the control portion 10 calculates the start timing engine torque Tes1. It is noted that the method for calculating the start timing engine torque Tes1 is the same as the method described in the steps S16-1 through S16-4 of the torque-down control indicated in Fig. 5. After the process of the step S17-1, the program goes to the step S17-2.
At the step S17-2, the control portion 10 corrects the start timing engine torque Tes1 based on the current engine torque Ne. The detail thereof will be explained hereinafter. The control portion 10 calculates the first rotation speed difference Δa by subtracting the first defined rotation speed N1 from the current engine rotation speed Ne (point "2" in Fig. 3) based on the following formula (3): $Δa = Ne - N 1$

Δa: First rotation speed difference
Ne: Current engine rotation speed
N1: First defined rotation speed.

Next, the control portion 10 calculates the second rotation speed difference Δb by subtracting the second defined rotation speed N2 from the current engine rotation speed Ne (point "2" in Fig. 3)based on the following formula (4): $Δb = N 2 - Ne$

Δb: Second rotation speed difference
Ne: Current engine rotation speed
N2: Second defined rotation speed.

Next, the control portion 10 calculates the corrected start timing engine torque Tes2 by substituting the required engine torque Ter, the start timing engine torque Tes1, the first rotation speed difference Δa and the second rotation speed difference Δb into the following formula (5): $Tes 2 = (Tes 1 \times Δb + Ter \times Δa) / (Δa + Δb)$

Tes2: Corrected start timing engine torque
Tes1: Start timing engine torque
Ter: Required engine torque
Δa: First rotation speed difference
Δb: Second rotation speed difference.

After the process of the step S17-2, the program goes to the step S17-3.
At the step S17-3, when the control portion 10 judges that the corrected start timing engine torque Tes2 is smaller than the required engine torque Ter (S17-3; YES), the program goes to the step S17-4 and when the control portion 10 judges that the corrected start timing engine torque Tes2 is equal to or more than the required engine torque Ter (S17-3; NO), the program goes to the step S17-5.
At the step S17-4, the control portion 10 controls the throttle valve 22, fuel injection device 28 and the ignition device so that the engine torque Te which the engine 2 generates becomes the corrected start timing engine torque Tes2 calculated at the step S17-2. After the process of the step S17-4, the program returns to the step S11 in Fig. 4.
At the step S17-5, the control portion 10 controls the throttle valve 22, fuel injection device 28 and the ignition device so that the engine torque Te which the engine 2 generates becomes the required engine torque Ter. After the process of the step S17-5, the program returns to the step S11 in Fig. 4.

(Explanation of the vehicle start)

The "clutch/engine cooperative control" at the start of the vehicle will be explained hereinafter using Figs. 2, 4 and 10.

Under this state, since the brake pedal 56 is depressed, the judgment at the step S11 in Fig. 4 is "NO" and the program goes to the step S18. The normal control is then executed. In other words, the control of the engine 2 is subject to the acceleration operation by the operator of the vehicle. Under this state, since the acceleration pedal 51 is not depressed, the engine rotation speed Ne is under an idle rotation speed (for example, 700 r.p.m.).

Under this state, since the clutch 3 is completely disconnected, the judgment in the step S12 in Fig. 12 is "NO" and the program goes to the step S18. Then, normal control is executed. The control of the engine 2 is subject to the acceleration operation by the operator of the vehicle. Under this state, since the acceleration pedal 51 is depressed, the engine rotation speed Ne and the engine torque Te are subject to the acceleration opening degree Ac.

Under this state, since the clutch 3 is in half clutch state, the judgment at the step S12 in Fig. 4 is "YES", and since the clutch difference rotation speed Δc is equal to or more than the defined difference rotation speed A (for example, 500 r.p.m.), the judgment at the step S14 is "YES". Further, since the engine rotation speed Ne is less than the second defined rotation speed N2 (for example, 2000 r.p.m.), the program goes to the step S18 based on the judgment at the step S14to execute normal control.

Under this state, since the engine rotation speed Ne exceeds the second defined rotation speed N2 (for example, 2000 r.p.m.), according to the judgment at the step S14 in Fig. 4, the program goes to the step S17 and the limited torque-down control starts. Then, under the limited torque-down control, when the corrected start timing engine torque Tes2 is judged to be larger than the required engine torque Ter (S17-3 in Fig. 9; YES), the engine 2 is controlled so that the engine torque becomes the corrected start timing engine torque Tes2.

Under this state, since the engine rotation speed Ne has exceeded the first defined rotation speed N1 (for example, 2500 r.p.m.), according to the judgment at the step S14 in Fig. 4, the program goes to the step S16 to start the limited torque-down control. Under the torque-down control, when the start timing engine torque Tes1 is judged to be larger than the required engine torque Ter (S16-5 in Fig. 5: YES), the engine 2 is controlled so that the engine torque becomes the start timing engine torque Tes1.

Under this state, since the engine rotation speed Ne is smaller than the first defined rotation speed N1, the program goes to the step S17 by the judgment at the step S14 in Fig. 14 to start the limited torque-down control. Under the limited torque-down control, when the corrected start timing engine torque Tes2 is judged to be larger than the required engine torque Ter (S17-3 in Fig. 9: YES), the engine 2 is controlled so that the engine torque Te becomes the corrected start timing engine torque Tes2.

Under this state, since the clutch difference rotation speed Δc is smaller than the defined difference rotation speed A (for example, 500rpm), the judgment at the step S14 is "NO" and the program goes to the step S18 to finish the limited torque-down control. Then the normal control is started.

Thereafter the clutch difference rotation speed Δc becomes zero and the clutch 3 is completely engaged to finish the vehicle start operation and the engine 2 is controlled under the normal control operation.

(Advantageous effects of the embodiment)

As apparent from the explanation above, the control portion 10 (start timing engine torque calculating means) calculates the start timing engine torque Tes1 based on the clutch transmitting torque Tc at the step S16-4 in Fig. 5. Further, the control portion 10 (engine control means) controls the engine 2 so that the engine torque Te agrees with the start timing engine torque Tes1 at the step S16-6 in Fig. 5, when the clutch difference rotation speed Δc is judged to be equal to or more than the defined difference rotation speed A, at which the clutch 3 is in the half clutch state (S14 in Fig. 4: judged to be YES) and the engine rotation speed Ne is judged to be equal to or more than the first defined rotation speed N1 (by the judgment at the step S15 to proceed to the step S16).
As explained, when the vehicle is starting under the clutch 3 being in half clutch state, the engine 2 is controlled to output the start timing engine torque Tes1 which is calculated corresponding to the clutch transmitting torque Tc when the engine rotation speed Ne becomes equal to or more than the first defined rotation speed N1. Thus, when the operator of the vehicle releases the clutch pedal 53 and thereby the clutch transmitting torque Tc becomes decreased, the start timing engine torque Tes1 also decreases. Therefore, the start timing engine torque Tes1 decreases before the rising of the engine rotation speed Ne due to the decrease of the clutch transmitting torque when the engine rotation speed Ne is equal to or more than the first defined rotation speed N1. This can prevent the excess rising of the engine rotation speed Ne.
Accordingly, since the excess rising of the engine rotation speed Ne can be prevented, worsening of fuel efficiency can be prevented and also a large noise generation at the start of the vehicle can be prevented. Further, the damage and the deterioration of clutch disc 32 due to the excess heat can be prevented.
Further, the control portion 10 (engine rotation speed decrease torque calculating means) calculates the engine rotation speed decrease torque Ten at the step S16-2 in Fig. 5. The control portion 10 (start timing engine torque calculating means) calculates the start timing engine rotation speed Tes1 by adding the engine rotation speed decrease torque Ten according to the formula (1) above at the step S16-4 in Fig. 5.
Thus the start timing engine torque Tes1 is calculated to have a value smaller by the engine rotation speed decrease torque Ten which decreases the engine rotation speed Ne at the torque-down control. Therefore when the engine rotation speed Ne is equal to or more than the first defined rotation speed N1, the engine rotation speed Ne can be decreased to surely prevent the excess rising of the engine rotation speed Ne.
Further, the control portion 10 (maintaining torque calculating means) calculates the maintaining torque Tk based on the load acting on the engine 2 in the maintaining torque calculating process shown in Fig. 7. Then, the control portion 10 (start timing engine torque calculating means) calculates the start timing engine torque Tes1 by adding the maintaining torque Tk at the step S16-4 in Fig. 5.
Accordingly, the start timing engine torque Tes1 is calculated by adding the decrease of the load when, for instance, the auxiliary machine driven by the engine 2 is stopped to decrease the load on the engine 2. This can surely prevent the excess rising of the engine rotation speed Ne.
Further, the control portion 10 (engine control means) controls the engine 2 so that the engine torque Te becomes the required engine torque Ter when the required engine torque Ter is equal to or less than the start timing engine torque Tes1 or Tes2 (S16-5 in Fig. 5 or S17-3 in Fig. 9: NO).
By this processing, when the required engine torque Ter is equal to or less than the start timing engine torque Tes1, the engine 2 is controlled to output the required engine torque Ter which reflects the intention of the operator of the vehicle. This control can prevent the operator of the vehicle from having an unpleasant feeling because the engine torque Te and the intention of the operator do not deviate from each other. At the same time excess rising of the engine rotation speed Ne can be prevented.
Still further, the control portion 10 (corrected start timing engine torque calculating means) calculates the corrected start timing engine torque Tes2 which receives more influence from the start timing engine torque Tes1than the required engine torque Ter, as the more the engine rotation speed Ne approximates closer to the first defined rotation speed N1from the second defined rotation speed N2 at the step S17-2 in Fig. 9 based on the required engine torque Ter and the start timing engine torque Tes1, when the engine rotation speed Ne is judged to be less than the first defined rotation speed N1 and equal to or more than the second defined rotation speed N2 (Judgment to proceed to the step S17 at the step S15 in Fig. 4). Thus the control portion 10 executes the limited torque-down control so that the engine 2 outputs the corrected start timing engine torque Tes2.
Thus, at the vehicle start, when the engine rotation speed Ne is increased gradually, the engine control is transferred from the normal control to the torque-down control via the limited torque-down control where the influence of the torque-down control is gradually increasing. This can prevent the sudden change of the engine torque Te to thereby prevent the operator from feeling unpleasantly.
Further, the clutch stroke Cl which corresponds to the operating amount of the clutch pedal 53 is detected by the clutch sensor 54 (clutch transmitting torque obtaining means). The control portion 10 obtains the clutch transmitting torque Tc by referencing the clutch stroke Cl to the clutch transmitting torque mapping data shown in Fig. 2. Thus, the clutch transmitting torque Tc can be surely obtained with a simple structure and a simple method.
Further, the control portion 10 (engine rotation speed decrease torque calculating means) calculates the engine rotation speed decrease torque to be zero (0) at the step S16-2 in Fig. 5, when the current engine rotation speed Ne is slower than the target engine rotation speed Net. Thus, the excess drop of the engine rotation speed Ne can be avoided to prevent the operator of the vehicle from feeling uncomfortable and also to prevent generation of an engine stall.
Further, the control portion 10 calculates the absolute value of the engine rotation speed decrease torque Ten such a manner that the faster the current engine rotation speed Ne is than the target engine rotation speed Net, the larger the absolute value of the engine rotation speed decrease torque Ten becomes. This means that the calculation is made in such a manner that the more the current engine rotation speed Ne increases to deviate from the target engine rotation speed Net, the larger the absolute value of the engine rotation speed decrease torque Ten becomes. Accordingly, the engine rotation speed Ne which becomes faster than the target engine rotation speed Net can be surely decreased to the target engine rotation speed Net to prevent excess rising of the engine rotation speed Ne.
When the vehicle speed detected by the vehicle speed detecting means is faster than a predetermined speed (S13 in Fig. 4: NO), the control portion 10 executes the normal control at the step S18. Therefore, if the operator of the vehicle should perform a half clutch operation while the vehicle is running with a vehicle speed V faster than the predetermined speed after the vehicle start, the execution of the torque-down control and the limited torque-down control can be prevented. Therefore, giving an unpleasant feeling to the operator of the vehicle can be prevented.

(Second embodiment)

The explanation of the second embodiment will be made with the portions different from the previously explained embodiment. According to the second embodiment, at the step S16-2 in Fig. 5, the control portion 10 calculates the engine rotation speed decrease torque Ten by the following method instead of using the engine rotation speed decrease torque calculating data.
First, the control portion 10 calculates the engine rotation speed change ωe which is the change of the engine rotation speed Ne per unit time. More specifically, the time Tn necessary for decreasing the engine rotation speed to the target engine rotation speed Net from the current engine rotation speed Ne is calculated. This time Tn can be calculated based on the engine friction torque Tef.
Then the control portion 10 calculates the engine rotation speed change ωe by dividing the value obtained by subtracting the current engine rotation speed Ne from the target engine rotation speed Net by the necessary time Tn.
Next, the control portion calculates the engine rotation speed decrease torque Ten based on the following formula (10). $Ten = le \times ωe$

Ten..... Engine rotation speed decrease torque Ten:
le.... Engine inertia:
ωe.... Engine rotation speed change.

The engine inertia le is a moment of inertia of a rotation member of the engine 2. Such rotation member of the engine 2 includes crank shaft, con-rod, piston, output shaft 21, flywheel 31, clutch cover 33, pressure plate 35 and diaphragm spring 34. The engine inertia le is predetermined in advance.

(Other embodiments)

Embodiments other than the hitherto explained embodiment will be explained hereinafter. According to the embodiments of the invention explained above, the target engine rotation speed Net is set to be the first defined rotation speed N1. However, the target engine rotation speed Net may be set to be the second defined rotation speed N2 or to be a rotation speed other than these defined rotation speeds.
According to the embodiment explained above, operating force of the clutch pedal 53 is transmitted to the release bearing through the master cylinder 55, hydraulic pressure conduit 58 and slave cylinder 38. However, the operation force of the clutch pedal 53 may be transmitted to the release bearing 37 through the mechanical elements such as wire, rod and gears.
According to the embodiment explained above, the corrected start timing engine torque Tes2 is calculated by proportionally distributing the required engine torque Ter and the start timing engine torque Tes1 according to the proportional ratio calculated using the rotation difference between the current engine rotation speed and the first defined rotation speed N1 and the rotation difference between the current engine rotation speed and the second defined rotation speed N2 based on the formula (5) above. However, a different method may be used for calculation of the corrected stat timing engine torque Tes2, wherein based on the required engine torque Ter and the start timing engine torque Tes1, the corrected start timing engine torque Tes2 is calculated so that the closer the engine rotation speed Ne approximates to the first defined rotation speed N 1 from the second defined rotation speed N2, the more the engine rotation speed Ne receives influence from the start timing engine torque Tes1 than from the required engine torque Ter.
According to the embodiment explained above, the clutch transmitting torque Tc is calculated by referencing the clutch stroke Cl detected by the clutch sensor 54 to the clutch torque transmitting torque mapping data which represent the relationship between the clutch stroke Cl and the clutch transmitting torque Tc as shown in Fig. 2. However, as disclosed in a JP patent publication No. 2008-157184 A , it is possible that the clutch transmitting torque Tc is presumed based on the change amount of the clutch stroke Cl per unit time and then the required engine torque Ter is presumed thereby.
According to the embodiment explained above, the clutch transmitting torque Tc is calculated based on the detection signal from the clutch sensor 54. However, the clutch transmitting torque Tc may be calculated based on the information such as, the engine inertia, the engine friction torque, the rotation speed of the transmission input shaft 41 at the time the engagement starts, the current rotation speed of the transmission input shaft 41 and a time elapsed from the start of the engagement.
According to the embodiment explained above, the clutch sensor 54 detects the stroke amount of the master cylinder 55. However, the clutch sensor 54 may be a sensor which detects the operating amount of the clutch pedal 53, master pressure of the master cylinder 55, the stroke or the hydraulic pressure of the slave cylinder 38 or the stroke amount of the release bearing 37.
According to the embodiment explained above, the control portion 10 calculates the vehicle speed V based on the transmission output shaft rotation speed No detected by the transmission output shaft rotation speed sensor 46. However, the control portion 10 may calculate the vehicle speed V based on the vehicle wheel rotation speed which is detected by the vehicle wheel speed sensor which detects the wheel rotation speed of the vehicle, or a sensor which detects the rotation speed of an axis rotating in association with the vehicle wheel.
According to the embodiment explained above, an oil temperature of the lubrication oil lubricating the engine 2 is detected by the oil temperature sensor 25. However, the oil temperature may be presumed based on the detection signal from the water temperature sensor which detects the water temperature of cooling water circulating through the engine 2.
According to the embodiment explained above, the clutch operating member for transmitting the operating force of the operator of the vehicle to the clutch 3 includes is the clutch pedal 53. However, the clutch operating member is not limited to the clutch pedal 53, but a clutch lever may be used as the clutch operating member. Similarly, instead of using the acceleration pedal 51 for adjusting the acceleration opening degree Ac, for example, acceleration grip for adjusting the acceleration opening degree Ac may be used. Further, the vehicular drive apparatus according to the embodiment can be apparently used for a motor cycle or other vehicles.
According to the embodiment explained above, a single unit control portion 10 controls the engine 2 and at the same time executes the clutch/engine cooperative control as shown in Fig. 4. However, as a different embodiment, it is possible that an engine control portion controls the engine 2 and the control portion 10 connected to the engine control portion through a communication means such as CAN (Controller Area Network) executes the clutch/engine cooperative control.
According to the embodiment explained above, the vehicle includes a manual transmission 4. However, the technical idea of this invention can be applied to a vehicle which does not includes a manual transmission but includes an input shaft which is rotatable in association with the rotation of the drive wheels 18R and 18L and connected to the clutch disc 32.
According to the embodiment explained above, the invention is applied to the timing of the start of the vehicle, but the invention is applicable to the driving under a very slow vehicle speed situation where an excess dropping of the engine rotation speed is prevented by using the half-clutch operation to appropriately slide the clutch where the vehicle is running in a heavy traffic jam or the vehicle is under garage parking.

[Reference Signs List]

In the drawings:

1: vehicular drive apparatus, 2: engine, 3: clutch, 10: control portion (required engine torque calculating means, start timing engine torque calculating means, engine control means, clutch transmitting torque obtaining means, engine rotation speed decrease torque calculating means, load obtaining means, maintaining torque calculating means), 19: brake device (braking force applying means), 21: output shaft, 25: oil temperature sensor (load obtaining means) 41:transmission input shaft (input shaft), 46: transmission output shaft rotation speed sensor (vehicle speed detecting means), 51: acceleration pedal (engine operating means), 52: acceleration sensor (required engine torque calculating means), 53: clutch pedal (clutch operating member), 54: clutch sensor (clutch transmitting torque obtaining means, clutch operating amount detecting means), 56: brake pedal (brake operating means), 57: brake sensor (brake operating amount detecting means),
"t": oil temperature, "V": vehicle speed, "A": defined difference rotation speed, N1: first defined rotation speed, N2: second defined rotation speed, "Δc": clutch difference rotation speed, "Te": engine torque, "Ter": required engine torque, "Tes1": start timing engine torque (torque-down control timing), Tes2: corrected start timing engine torque (limited torque-down control timing), Tc: clutch transmitting torque, Ten: engine rotation speed decrease torque, Tk: maintaining torque, le: engine inertia, Net: target engine rotation speed, ωe: engine rotation speed change, Tef: engine friction torque, Ta: auxiliary machine torque, Tα: adjusting torque.

Claims

A vehicular drive apparatus comprising:
an engine outputting an engine torque to an output shaft;

an engine operating means operated for variably outputting the engine torque from the engine;

an input shaft which rotates in association with a rotation of a drive wheel of a vehicle;

a clutch provided between the output shaft and the input shaft for controlling a clutch transmitting torque therebetween to be variable;

a clutch operating means for operating the clutch to control the clutch transmitting torque to be variable;

a clutch transmitting torque obtaining means for obtaining the clutch transmitting torque which is generated by the clutch;

a required engine torque calculating means for calculating a required engine torque which is a required torque from the engine based on an operating amount of the acceleration pedal;

a start timing engine torque calculating means for calculating a start timing engine torque based on the clutch transmitting torque obtained by the clutch transmitting torque obtaining means; and,

an engine control means for executing a torque-down control by controlling the engine so that the engine torque becomes the start timing engine torque when a clutch difference rotation speed which is a difference rotation speed between the output shaft and the input shaft is equal to or more than a defined difference rotation speed and an engine rotation speed is equal to or more than a first defined rotation speed and executing a normal control by controlling the engine so that the engine torque becomes the required engine torque when the clutch difference rotation speed is less than the defined difference rotation speed.
The vehicular drive apparatus according to claim 1, further comprising an engine rotation speed decrease torque calculating means for calculating an engine rotation speed decrease torque which is a minus value torque necessary for decreasing the engine rotation speed, wherein the start timing engine torque calculating means calculates the start timing engine torque by adding the engine rotation speed decrease torque.
The vehicular drive apparatus according to claim 1or 2, further comprising:
a load obtaining means for obtaining a load acting on the engine; and

a maintaining torque calculating means for calculating a maintaining torque which is necessary for maintaining the engine rotation speed other than the clutch transmitting torque and the engine rotation speed decrease torque based on the load, wherein the start timing engine torque calculating means calculates the start timing engine torque by adding the maintaining torque
The vehicular drive apparatus according to any one of claims 1 through 3, wherein the engine control means controls the engine so that the engine torque becomes the required engine torque when the required engine torque is equal to or less than the start timing engine torque.
The vehicular drive apparatus according to any one of claims 1 through 4, further comprising:
a corrected start timing engine torque calculating means for calculating a corrected start timing engine torque so that the influence of the start timing engine torque becomes more than an influence of the required engine torque, as the engine rotation speed becomes closer to a first defined rotation speed from a second defined rotation speed based on the required engine torque and the start timing engine torque when the engine rotation speed is less than the first defined rotation speed and is equal to or more than the second defined rotation speed which is slower than the first defined rotation speed, wherein the engine control means controls the engine to execute a limited torque-down control so that the engine torque becomes the corrected start timing engine torque when the engine rotation speed is less than the first defined rotation speed and is equal to or more than the second defined rotation speed.
The vehicular drive apparatus according to any one of claims 1 through 5, wherein
the clutch transmitting torque obtaining means includes a clutch operating amount detecting means for detecting an operating amount of the clutch operating means.
The vehicular drive apparatus according to any one of claims 2 through 6, wherein the engine rotation speed decrease torque calculating means calculates the engine rotation speed decrease torque to be zero when a current engine rotation speed is slower than a target engine rotation speed which is a rotation speed of the engine to be a target upon decreasing the engine rotation speed and calculates an absolute value of the engine rotation speed decrease torque such that the faster the current engine rotation speed is than the target engine rotation speed, the larger the absolute value of the engine rotation speed decrease torque becomes.
The vehicular drive apparatus according to any one of claims 1 through 7, further comprising:
a vehicle speed detecting means for detecting a vehicle speed of a vehicle, wherein the engine control means executes the normal control when the vehicle speed detected by the vehicle speed detecting means is faster than a predetermined defined speed.