JPS58160661A - Vehicle power plant - Google Patents

Abstract

PURPOSE:To minimize the fuel consumption of an engine over its whole range of operation, by setting the required power output of the engine as a function of the operated quantity of an accelerator pedal and controlling the revolution speed and output torque of the engine at every required power output to minimize the fuel consumption. CONSTITUTION:The required power output of an engine 1 is prescribed as a function of the operated quantity of an accelerator pedal 18. The output torque 7 and revolution speed of the engine, which are such as to achieve the required power output at the minimum fuel consumption, are set as target values. The velocity ratio of a stepless transmission 4 is controlled to equalize the revolution speed of the engine to the target value. The degree of opening of an intake throttle valve is controlled to equalize the output torque of the engine to the target value. This results in operating the engine 1 at the minimum fuel consumption over the whole range of required power output.

Description

[Detailed description of the invention] The present invention relates to a vehicle power system equipped with a continuously variable transmission.

In conventional vehicles, the intake system throttle valve is connected to the accelerator pedal in the driver's cab via a link or wire, and the throttle opening is directly controlled by the driver's operation of the accelerator pedal, and the engine is controlled by the amount of air supplied accordingly. It increases or decreases the output torque. ◇In the case of a conventional transmission, the gear ratio is directly controlled by the driver's operation of the shift lever in the case of a manual transmission.
In the case of an automatic transmission, several gears are selected as a function of throttle opening and vehicle speed.

It is preferable for an internal combustion engine to be operated at a minimum fuel consumption rate, but the gear ratio of conventional transmissions is set in consideration of drivability in the case of acceleration and has a stepped ratio. It has been difficult to operate an internal combustion engine at a minimum fuel efficiency over the entire operating range.

An object of the present invention is to provide a vehicle power plant that can control the operation of an internal combustion engine at a minimum fuel efficiency over the entire operating range.

To achieve this object, according to the present invention, in a vehicle power system in which the rotation of an internal combustion engine is transmitted to drive wheels via a continuously variable transmission, the required horsepower of the internal combustion engine is determined by the operating amount of an accelerator pedal. The output torque and rotational speed of the internal combustion engine that can achieve the required horsepower at the minimum fuel consumption rate are determined as the target output torque and target rotational speed, and the continuously variable speed is set so that the rotational speed of the internal combustion engine becomes the target rotational speed. The gear ratio of the engine is feedback-controlled, and the amount of air or fuel supplied to the internal combustion engine is controlled by foot so that the output torque of the internal combustion engine becomes the target output torque.

Furthermore, according to the present invention, in a vehicle power system in which the rotation of an internal combustion engine is transmitted to drive wheels via a continuously variable transmission, the required horsepower of the internal combustion engine is determined as a function of the operating amount of an accelerator pedal, and the required horsepower is determined as a function of the operation amount of an accelerator pedal. The output torque and rotational speed of the internal combustion engine that can achieve the minimum fuel consumption rate are determined as the target output torque and target rotational speed, and the rotational speed of the internal combustion engine is set to the target rotational speed according to the required horsepower indicated by the accelerator operation amount. The gear ratio of the continuously variable transmission is feedback-controlled, and the intake system is controlled so that the output torque of the engine becomes the target output torque corresponding to the actual engine rotation speed of the internal combustion engine on the characteristic line of target rotation speed - target output torque. Throttle opening degree l Feedback controls the amount of air or fuel supplied to the internal combustion engine.

Further, according to the present invention, in a vehicle power system in which the rotation of an internal combustion engine is transmitted to drive wheels via a continuously variable transmission, the required horsepower of the internal combustion engine is determined as a function of the operation amount of an accelerator pedal, and the required horsepower is determined as a function of the operation amount of an accelerator pedal. The output torque and rotational speed of the internal combustion engine that can be achieved at the minimum fuel efficiency rate are determined as the target output torque and target rotational speed, and the rotational speed of the internal combustion engine is set to the target rotational speed according to the required horsepower indicated by the accelerator operation amount. The gear ratio of the continuously variable transmission is fed and controlled so that the output torque of the internal combustion engine is equal to the output torque of the internal combustion engine required to generate the required horsepower at the actual rotational speed of the internal combustion engine. Feed knock control is performed on the amount of air or fuel supplied to the internal combustion engine.

The present invention will be explained in more detail with reference to the drawings.

FIG. 1 shows a constant fuel consumption rate M (solid line) and a constant horsepower line (broken line) on the basis of engine rotational speed and engine output torque. The unit of the equal horsepower line is 281, and the unit of the equal fuel consumption rate line is g/
PS-h! be. The dash-dotted line shows the characteristics when the throttle valve is fully open, and the operating limit of the engine is present. Ai is a line connecting the points that have the minimum fuel consumption rate for each output horsepower,
The gear ratio f in conventional transmissions was set as line B, resulting in poor fuel efficiency. In the present invention, the required horsepower of the engine is set as a function of the amount of operation of the accelerator pedal, that is, the amount of depression.
The internal combustion engine is operated so that the engine rotational speed and engine output torque are defined by line A at each required horsepower. The engine rotation speed is controlled by a continuously variable transmission.
ouslyvaria'bjf'e transmis
sion: Hereinafter referred to as CVT. ), and the engine output torque is controlled by changing the intake system throttle opening. The function is determined on the assumption that the required horsepower increases as the amount of depression of the accelerator pedal increases.

Various CVT mechanisms have been proposed in the past, but in FIG. 2, a belt-driven type, which is compact and can transmit a large torque, will be explained.

In FIG. 2, the output shaft 2 of the internal combustion engine 1. is connected to the input shaft 5 of the CVT 4 via the clutch 3. Input shaft 5
and output shafts 6 are provided parallel to each other, the input side fixed disk 7 is fixed to the input shaft 5, and the input side movable disk 8 is movable in the axial direction, and is attached to the outer periphery of the input shaft 5 by a spline or a single bearing. etc., and the exit side
"The fixed disk 9 is fixed to the output shaft 6, and the output side movable disk 10 is fitted onto the outer periphery of the output shaft 6 with a spline or a Zeel bearing so as to be movable in the axial direction.

The pressure-receiving area of the movable disk is set so that the input side is larger than the output side, and the axial positions of the fixed disk and the movable disk are opposite to each other on the input side and the output side. fixed disk 7.9 and movable disk 8,
100 How far are the opposing surfaces from each other in the radial direction?
A belt 11 of increasing chi, hexagonal in shape and truncated conical cross section is hung between the disks on the input and output sides. Therefore, when tightening the fixed and movable disks, the radial contact position of the belt 11 on the disk surface changes continuously as the force changes. Input side disk 7.80
When the contact position of the belt 11 moves radially outward on the surface, the power of the output shaft 6 changes as shown in FIG. The signal is transmitted to the drive wheels (not shown). Torque sensor 15
detects the torque of the input shaft 5, and therefore the output torque Te of the internal combustion engine 1, from changes in the torsional stress or torsion angle in the input shaft 5. The accelerator pedal sensor 16 is connected to the driver's foot 1.
7, the amount of depression of the accelerator pedal 18 is detected. The opening degree of the intake throttle of the internal combustion engine l is controlled by an electromagnetic throttle actuator 19. Input side and output side rotation angle sensors 21 are respectively disks 7
．． The rotation angle of 1o, and therefore the rotation speed, is detected. The line pressure generation valve 24 is operated by the oil pump 25 and is operated by the oil pump 26.
By controlling the amount of oil as a hydraulic medium sent from the oil passage 27 through the oil passage 27,
Adjust line pressure P12 of 9. Output side movable disk 4
The oil pressure pump O is supplied with the line 7 pressure PA' via the oil passage 29. The flow rate control valve 30 controls the amount of oil flowing into and out of the input movable disk 8 .

In order to maintain the speed ratio e of CVT4 constant, oil path 3
3 and the line pressure oil passage 31 and drain oil passage 32 branching from the oil passage 29, in other words, in order to maintain a constant position of the input side movable disk 8 in the axial direction and increase the speed ratio e. Supplying oil from oil passages 31 to 33 and tightening between the input side discs 7° and 8* increases the force and increases the speed ratio e.
In order to reduce this, the hydraulic pressure of the hydraulic surge of the movable disk 8 is conducted to the atmosphere through the drain oil passage 32 to reduce the thrust between the input side disks 7 and 8.

The oil pressure in the oil passage 33 is f below the line pressure Pl, but since the piston action area of the hydraulic circulator on the input side movable disc 8 is larger than the piston action area of the hydraulic servo I on the output side movable disc 10, the input side disc 7. It is possible to make the force for tightening at 8 degrees greater than the force for tightening at 9 degrees and 100 degrees for the output side disc.

The electronic control unit 38 includes a D/A (digital/analog) converter 40, an input interface 41, an A/D (analog/digital) converter 42, a CPU 43, and an RA that are connected to each other by an address data node 39. M
44 and ROM45. The analog outputs of the torque sensor 15 and the accelerator pedal sensor 16 are sent to the A/D converter 42, and the ξ pulses of the rotation angle sensors 20.degree. 21 are sent to the input interface 41.

Outputs to the electromagnetic actuator 19, flow control valve 30, and line pressure generation valve 24 are sent from the D/A converter 40 via amplifiers 49, 50, and 51, respectively.
The figure shows the relationship between the input voltage and the output current of the amplifier 49 for the throttle actuator 19. Fourth
The figure shows the relationship 2 between the throttle actuator 190 input current and the intake system throttle opening. Therefore, the throttle opening increases in proportion to the amplifier 490 input voltage. FIG. 5 shows the relationship between the input voltage and output current of the flow control valve 30 increaser and width regulator 50, and FIG. It shows the relationship between Therefore, the speed ratio e is proportional to the change in the input current of the amplifier 500. Figure 7 shows the line pressure generation valve 24.
The relationship between the input voltage and the output current of the amplifier 51 is shown, and FIG. 8 shows the relationship between the input current of the line pressure generating valve 240 and the line pressure Pl.

Therefore, for changes in the input voltage of the amplifier 51,
The 1-line pressure P/ changes linearly. Line pressure generation valve 2
Even if the input current of 4 is 0, the line pressure Pl is P/1
(PA'l 10), even if a wire breakage or a failure occurs in the electronic control unit 38, a predetermined hydraulic pressure is supplied to the hydraulic servo of the movable disk 8.10, and the minimum torque transmission in the CvT4 is maintained. Secured.

FIG. 9 is a block Ii diagram of an embodiment of the present invention. In block 55, the amount of acceleration pedal depression Xacc is the required horsepower p
s'. The required horsepower Ps' is the amount of pedal stroke Xacc
It is set as a function of Xacc that increases as Xacc increases. In block 56't%, the required horsepower PS' is converted into the target rotational speed N'in of the engine, that is, the input shaft 5. The relationship between the required horsepower PS/ and the target rotational speed N'in is shown by line A in FIG. That is, the engine rotation speed at which the required horsepower PS' can be obtained at the minimum fuel consumption rate is the target rotation speed. 57 Ma target rotation speed Num
The deviation N'1n=Nin between the actual rotational speed N1n and the actual rotational speed N1n is determined.

58 is a feedback gain. Thus N′1n
-Nin -0, so the speed ratio e of the CVT 4 is controlled so that Nin is equal to N'in.

In block 60, the required horsepower PS' is converted into a target engine output torque T's. The relationship between the required horsepower Ps' and the target output torque T'e is shown by line A in Fig. 1, that is, the required horsepower Ps' can be obtained at the minimum fuel consumption rate of the required station P'sB/The output torque is the target output torque. It has 1 torque. At step 61, the deviation T'e-Te between the target output torque T's and the actual output torque Te is determined. 62 is a feed gain. Thus T'e-Te-0, therefore T
In block 66, where the throttle opening is controlled so that e becomes equal to T'e, the line pressure Pl is expressed as the input shaft 50 rotational speed Nin s, the output shaft 6 rotational speed No%ttq, as a function f of the engine output torque Te. Set. Transmission torque Tout % from belt 11 to output side discs 9, 10
When the contact position of the belt 11 on the output side disk 9.10 is defined as the distance 1iDout from the center of the totisks 9, 10, the belt 11 is on the output side disk 9.10. The required tightening of the output side discs 9 and 10 to ensure torque transmission without leaking on LO is proportional to Tout/Dout. PJ-α・Te-Sat...(1) However If α is a constant and e-1, line pressure Pl! is controlled to the necessary minimum level, and engine loss can be suppressed.Out can also be calculated using another approximate formula.

FIG. 1O is a flowchart of a program that performs control according to block 111 of FIG. In step 69, the accelerator pedal 18 is inputted from the accelerator pedal sensor 16.
Read the amount of depression Xacc. Step 70't% is X
Calculate the required horsepower ps' from acc-PS'vuzzo. If the Xacc-PS' map does not contain the Xacc read in one step 691, the sweep method is used. Step 7
1-'+1' calculates the target rotational speed N'in f from the PS'-N'in map. In step 72, the current rotation speed Nin is read from the input from the input side rotation angle sensor 20. In step 73, the output voltage Vin to the flow control valve amplifier 5o is determined as Vin = K1 (N'in -Ni
Calculated from T.n). However, Kl is a gain of 58 feet. Step 741 is PS'-T'
The target output torque T'e' is calculated from the e-map. In step 75, the current output torque Te is read from the input from the torque sensor 15. In step 76, the output voltage vth to the throttle actuator amplifier 49 is set to Vth.
-Vth-1-1-K2 (T'e = Te).

However, vth is the Vth calculated at the previous execution of step 76, and 2 is the gain 1 of the gain 62 above the feet. In step 77, the line pressure generating valve amplifier 5
1 to Vl- to 3.Te-Re 171. ．．
□□. r, near '6t, 3°. ,ah. .

The rotational speed of the machine is controlled by the serve oil pressure of the input side disk of the CVT 4, but the response of the CVT 4 is inferior to that of the throttle actuator 19.
In the embodiment shown in FIG. 9, for example, the DI shown in FIG.
When moving from to D2, or vice versa, the output torque changes first and the engine operation does not move on At1jl but on Ll and L2, resulting in a worsening of the fuel efficiency. Embodiment □, □, 7, □, □, □ and □゛ can be done according to the block diagram of FIG. 11. In FIG. 11, parts corresponding to those in FIG. 9 are indicated by the same reference numerals, and the explanation thereof will be omitted, and only the different parts will be explained. The target output torque T'e is calculated in block 81 from the required horsepower and from the actual rotational speed Nin. Therefore, the target output torque T'e is the actual engine rotational speed N.
Since it is set according to the A line from IN, engine control is possible even in the event of an emergency. ;I> is avoided.

Note that FIG. 11f shows the line pressure control block 66 in FIG.
, 51, and 24 are omitted, but in an actual device, line pressure control is performed at the same time.

FIG. 12 shows the control shown in the block i diagram of FIG. 11? This is a diagram of a program to be executed. In FIG. 12, steps that perform the same processing as the steps in FIG.

Step 84-t' calculates the target output torque T43 from a map in which the relationship between the actual rotational speed Nin and the target output torque T'e is determined according to line A in FIG.

In the embodiment f of FIG. 11, in the transient state, the driver's required horsepower P
The difference between S' and the actual horsepower ps is large (at the time of transition f, the actual horsepower ps is smaller than the required horsepower ps'), resulting in poor drivability. The following embodiment shown in FIG. 13 can improve the drawbacks of the embodiment shown in FIG. 11. The target output torque T'e is determined in block 86 by the current engine rotational speed Ninff1.
It is set as the engine output torque that achieves the required horsepower ps'. That is, T's −K 4・P S'/ Nin
, however, 4 has a constant 1. In this case, it is necessary to provide the internal combustion engine 1 with the ability to achieve the set engine output. This improves drivability during transient conditions. Furthermore, the 13th
Although the line pressure control blocks 66, 51, and 24 in FIG. 9 are omitted in the block diagram shown in the figure, the actual drive device 1 controls the line pressure at the same time.

FIG. 14 is a flowchart of a program that executes the control shown in the block diagram of FIG. 13. Steps that perform the same processing as the steps in FIG. 10 are indicated by reference numerals with a suffix C, and their explanation will be omitted. In step 88, the target output torque Te f T'e = K 4 ·
Calculated from P S'/Nin.

As described above, according to the present invention, the required horsepower is determined as a function of the operation amount of the accelerator pedal, and the engine output torque and engine rotation speed that achieve the required horsepower at the minimum fuel efficiency rate are set as target values, and the engine rotation speed is set as the target value. The speed ratio of the CVT is controlled so that the engine output reaches the target value, and the intake system throttle opening is controlled so that the engine output reaches the target value. As a result, the engine can be operated at the minimum fuel ratio over the entire range of required horsepower.

[Brief explanation of drawings]

Fig. 1 is a diagram showing equal horsepower weight lines and equal fuel efficiency lines on the coordinate system of engine rotational speed-output torque, Fig. 2 is a configuration diagram of a vehicle power plant to which the present invention is applied, and Fig. 3 is a diagram showing the input/output characteristics of the throttle actuator and amplifier for the eta. Figure 4 is a diagram showing the relationship between throttle actuator input and throttle opening, and Figure 5 is a diagram showing the relationship between throttle actuator input and throttle opening.
Figure 6 is a diagram showing the relationship between the input of the flow control valve and the speed ratio of the CVT, Figure 7 is a diagram showing the input/output characteristics of the line pressure generating valve amplifier, and Figure 8 is a diagram showing the input/output characteristics of the line pressure generating valve amplifier. 9 is a block diagram of an embodiment of the present invention; FIG. 10 is a flowchart of a program according to the block diagram of FIG. 9; The figure is a block diagram of another embodiment of the present invention, and Figure 12 is a block diagram of another embodiment of the present invention.
FIG. 13 is a block diagram of another embodiment of the present invention, and FIG. 14 is a flow chart of a program according to the block diagram of FIG. 13. 1... Internal combustion engine, 4... c V T i 15...
・Torque sensor, 18... Acceleration pedal, 19... Throttle actuator, 2o... Rotation angle sensor, 3
0...Flow rate control valve, 38...Electronic control device. Therefore, dD@YoQ-L ÷ Fig. 3 Input voltage of amplifier 49 Input current of throttle actuator 19 0 Input voltage of amplifier 51 Fig. 8 Input current of line pressure generating valve 24

Claims (1)

[Claims] 1. In a vehicle power system in which the rotation of an internal combustion engine is transmitted to drive wheels via a continuously variable transmission, the required horsepower of the internal combustion engine is determined as a function of the operating amount of an accelerator pedal, and the required horsepower is determined as a function of the operating amount of an accelerator pedal. The output torque and rotational speed of the internal combustion engine that can achieve the minimum fuel efficiency rate of 1 are determined as the target output torque and target rotational speed, and the gear ratio of the continuously variable transmission is adjusted continuously so that the rotational speed of the internal combustion engine becomes the target rotational speed. 1. A power plant for a vehicle, characterized in that the amount of air or fuel supplied to the internal combustion engine is controlled in a linear manner so that the output torque of the internal combustion engine becomes a target output torque. 2. The continuously variable transmission is belt-driven! Yes, the servo oil pressure of the output side disc of this belt-driven continuously variable transmission is
It is characterized by maintaining the line pressure at a level that ensures torque transmission between the output side disk and the belt, and controlling the speed ratio e of the belt-driven continuously variable transmission by changing the servo oil pressure of the input side disk. A vehicle power plant according to claim 1. 3. Transmission torque Tout from the belt to the output side disc
If the distance between the contact position of the belt on the output side disk and the center of the output side disk is defined as Dout, the line pressure Pl is increased as i increases. power plant for vehicles. 4. The vehicle power plant according to claim 3, wherein Pg is a function of Te.-e + 1-. 5. In a vehicle power system in which the rotation of the internal combustion engine is transmitted to the drive wheels via a continuously variable transmission, the required horsepower of the internal combustion engine is determined as a function of the vehicle operating the accelerator pedal, and the required horsepower is achieved at the minimum fuel efficiency rate. The output torque and rotational speed of the internal combustion engine that can be produced are determined as the target output torque and target rotational speed, and the continuously variable transmission is set so that the rotational speed of the internal combustion engine becomes the target rotational speed according to the required horsepower indicated by the accelerator operation amount. The gear ratio is feedback-controlled, and the output torque of the engine is supplied to the internal combustion engine so that it becomes the target output torque corresponding to the actual engine rotational speed of the internal combustion engine on the characteristic line of target rotational speed - target output torque. 6. A vehicle power system characterized in that the amount of air or the amount of fuel is controlled by foot control 6. A power system for a vehicle in which the rotation of an internal combustion engine is transmitted to drive wheels via a continuously variable transmission, wherein the internal combustion engine The required horsepower of the engine is determined as a function of the operating amount of the accelerator pedal, and the output torque and rotational speed of the internal combustion engine that can achieve the required horsepower at the minimum fuel consumption rate are determined as the target output torque and target rotational speed. The gear ratio of the continuously variable transmission is feedback-controlled so as to achieve the target rotational speed according to the required horsepower indicated by the manipulated variable, and the required horsepower 3 is generated at the actual rotational speed of the internal combustion engine. A power unit for a vehicle, such as an internal combustion engine, which controls the amount of air or fuel supplied to an internal combustion engine.