JPS6084462A - Line pressure control system in infinitely variable transmission for vehicle - Google Patents

Abstract

PURPOSE:To prevent efficiency of fuel consumption from degradation and a belt or the like from shortening of life by providing a control means for controlling line pressure in relation to the atmospheric pressure in a line pressure control system of CVT. CONSTITUTION:The output of a learning valve calculating means 92 is sent to the input of a torque correction factor calculating means 94 which calculates the correction factor Kt sent to the input of an engine torque calculating means 96 so that line pressure Pl controlled by a relief valve 32 is controlled in relation to the atmospheric pressure. Thus, when a vehicle moves from a plain to a high- land, the line pressure Pl is prevented from excessively exceeding a value corresponding to actual engine torque Te to produce an excessive press force against a belt, so that the efficiency of fuel consumption can be prevented from degradation and the lives of parts such as the belt can be prevented from being shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a line pressure control device for a continuously variable transmission (hereinafter referred to as CVT J) used as a single force transmission device for a vehicle.

BACKGROUND TECHNOLOGY CVT can continuously control the speed ratio e (=output side rotational speed N0uL/input side rim speed N1n), and maintains the engine with good fuel consumption2! It is used as a single force transmission device that can be operated at J rate.

In a belt type CVT, engine power is transmitted from the input pulley to the 1st upper blade pulley via the belt, and the belt pushing force is generated by the single force of the input 1ijl pulley and the output pulley, and usually the belt υ pushing force by the output pulley. is controlled by line pressure. It is clear that line H2 is controlled to a value that can avoid belt strain and oil pump loss of drive. The engine torque Te is determined as a function of O and the engine rotational speed Ne, and the line pressure Pl is controlled in relation to the engine l-lux Te. However, 111
When both vehicles are traveling on high ground, the air density decreases, so even with the same throttle opening θ, the engine torque Te decreases compared to when the vehicle is on flat ground.

In conventional line pressure control devices, line pressure P related to atmospheric pressure
Since l is not corrected and the engine torque Te is calculated assuming the case on flat ground, when driving the vehicle at high altitudes, the line pressure may be higher than the appropriate value according to the actual engine torque Te. , The pressing force of the belt is excessive.

This increases belt friction, worsens fuel consumption 4S, and shortens the life of parts such as the belt.

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a CVT control method that can control line pressure to an appropriate value regardless of the altitude at which a vehicle travels.

To achieve this object, the CVT line pressure control device of the present invention comprises control means for controlling the line pressure 1) l in relation to atmospheric pressure.

Therefore, when the vehicle moves from flat ground to high ground, it is avoided that the line pressure Pl becomes excessively large compared to the value corresponding to the actual engine torque Te, causing an excessive pressing force on the belt.
Deterioration of fuel consumption efficiency and reduction in the life of parts such as belts can be prevented.

During the engine air-fuel ratio feedback control period, the engine load,
For example, the basic fuel injection amount calculated from Q/Ne (where Q is the intake air flow collapse and Ne is the engine rotational speed) is corrected in relation to the feedback signal from the oxygen sensor in the exhaust system. In addition, in order to set the air-fuel ratio to an appropriate value during the air-fuel ratio open-loop control period such as during warm-up, the fuel correction HA based on the feedback signal during feedback control 1g1 is set as a learning value, and in the next open-loop control period, the fuel The injection amount is corrected based on the learned value. Culm, fuel injection II+ where the air density decreases as the vehicle altitude increases
Since the feedback correction amount for correcting r m and maintaining the air-fuel ratio of the air-fuel mixture at the stoichiometric air-fuel ratio increases, the atmospheric pressure and the feedback correction amount have a functional relationship with each other. In a preferred embodiment of the invention, the feedback correction 11
1. Therefore, the line pressure Pl is controlled in relation to the learned value. Since a learned value is used, an atmospheric pressure sensor can be omitted.

Furthermore, according to a preferred embodiment of the present invention, the engine torque at a flat ground, that is, the standard atmospheric pressure, is taken as the Sakamoto value, and this basic value is calculated from the throttle opening degree 0 and the engine rotational speed Ne, and the Φ output Basic value and feedback correction 'nk,
Therefore, the engine torque is calculated from the I″ff learning value, and the line pressure is controlled in relation to this engine torque.

Example The present invention will be described in detail with reference to the drawings.

In FIG. 1, the CVTIO has an input shaft 12 and an output shaft 14 that are parallel to each other. The input shaft 12 is connected to the engine 16
The crankshaft 18 is provided coaxially with the crankshaft 18 , and is connected to the crankshaft 18 via a clutch 20 . The input pulleys 22a and 22b are provided opposite to each other, and one of the input pulleys 22a is provided as a movable pulley on the input shaft 12 so as to be movable in the axial direction and fixed in the rotational direction.
The other input side pulley 22b is a fixed pulley that connects the input shaft 1.
It is fixed at 2. Similarly, the output side pulley 24a.

24b are also provided opposite to each other, one output side pulley 248 is fixed to the output shaft I4 as a fixed pulley, and the other output side pulley 24b is a movable pulley, movable in the axial direction and fixed in the rotational direction. It is provided on the output shaft 14. The opposing surfaces of the input pulleys 22a, 22I] and the output pulleys 24a, 24b are formed in a tapered shape, and the belt 26 with an isosceles trapezoid cross section is attached to the input pulleys 22a, 22I.
2b and the output pulleys 24a, 24b. The oil pump 28 sends oil from the /dl reservoir 30 to the pressure regulating valve 32. The regulating valve 32 is composed of an electromagnetic relief valve, and controls the line pressure of the oil passage 36 by changing the oil release t4↓ to the drain 34, and the line pressure of the oil passage 36 is controlled by the hydraulic cylinder of the output side pulley 241+ and It is sent to the flow control valve 38. Flow h↓The control valve 38 is connected to an oil passage 40 that is regulated to the hydraulic cylinder of the input pulley 22a.
The supply flow rate of oil from the oil passage 36 to the oil passage 40
The 4Vl outflow iu of oil from the drain 34 to the drain 34 is controlled. The pressing force of the input pulleys 22a, 22b and the output pulleys 24a, 24b with respect to the belt 26 is controlled by the hydraulic pressure of the input hydraulic cylinder and the output hydraulic cylinder, and the input pulleys 22a, 22b and the output pulley are controlled in relation to this pressing force. The radius of engagement of the belt 26 on the tapered surfaces of the side pulleys 24a, 24b changes, and as a result, CV'l'IO
Speed ratio e (=: Nouj/Nin, where N
out is the speed around the output shaft 14, Nin is the input shaft 12
In this embodiment, it is Nin - engine mouth transmission speed Nc. ) changes. In order to suppress the drive loss of the oil pump 28, the line pressure of the output side hydraulic cylinder is controlled to the minimum necessary value that can avoid belt 26 slippage and ensure single force transmission, and the line pressure of the input side hydraulic cylinder is The speed ratio e is controlled by Note that the hydraulic pressure of the input side hydraulic cylinder ≦ the hydraulic pressure of the output side 411-pressure cylinder, but since the pressure receiving area of the input side hydraulic cylinder>the pressure receiving area of the output side hydraulic cylinder, the input side pulley 22a.

The pressing force of the output pulleys 22b can be made larger than the suppressing forces of the output pulleys 24a and 24b. Input side rotation angle sensor 42
and the output side rotation angle sensor 44 detects the rotation speed Nln+Nout of the input shaft 12 and the output shaft load 4, respectively,
Water temperature sensor 46 detects the temperature of the cooling water of engine 16. An accelerator pedal 50 is provided in the driver's seat 48, a throttle valve in the intake passage is interlocked with the accelerator pedal 50, and a throttle opening sensor 52 detects the throttle opening O. Shift 1 to upper position 54 is the shift lever located near the driver's seat.
-Detect range.

FIG. 2 is a block diagram of electronically controlled drawing.

The address data bus 56 is connected to the CPU 58. RAM 6
0. ROM62, I/I: (interface) 6
4. An A/D (analog/digital converter) 66 and an A/A (digital/analog converter) 68 are connected to each other.

1/F 64 receives pulse signals from input side rotation angle sensor 42, output side rotation angle sensor 44, and shift position 1g sensor 54, and A/D 66 receives pulse signals from input side rotation angle sensor 42, output side rotation angle sensor 44, and shift position 1g sensor 54. The D/A 68 receives analog signals from the oxygen concentration sensor 70 that is installed in the gas system and detects the oxygen humidity in the exhaust gas, and the air flow meter 72 that is installed in the intake passage and detects the intake air flow rate. and outputs a pulse signal to the flow rate control valve 38.

FIG. 3 is a flowchart of a learned value calculation routine for air-fuel ratio control. This routine is performed during air-fuel ratio feedback control 101 in a steady state after warm-up. In step 70, the intake air flow ff1Q is detected. In step 78, Q and the predetermined value Q], Q2 (however, Ql<02
), and if Ql≦Q≦02, that is, if the area is suitable for calculating the learned value, the process proceeds to step 8o, and if the area is other than that, the routine ends. In step 8°, the feedback correction coefficient Kf of the fuel injection amount is compared with a predetermined value Kl, and if Kf≧Kl, the process proceeds to step 82, and if Kf<old, the routine ends. The fuel injection jltQf per one fuel injection amount from the fuel injection valve during the feedback control aKA is calculated, for example, from the following equation.

q+ = (++Kt)・qb ... (]) However, Ql
+ is the basic fuel injection amount calculated from Q/Ne, and K
f·Qb is a feedback correction amount of the fuel injection amount.

If Kf<KI, the feedback correction amount of the fuel injection amount is small, so no learning value is detected. In step 82, Kf is substituted for the learned value Kg. During oven loop control area 1 of the air-fuel ratio, the fuel injection amount Qf per one fuel injection amount from the fuel injection valve is divided, for example, from the following equation.

Qf = (10Kg -1-Kx)・gb...
(2) However, l(x is a correction coefficient calculated from other parameters such as cooling water humidity.

In equation (1), the basic fuel injection 1r↓Qb is M for airtightness, so the air-fuel ratio is maintained at the stoichiometric air-fuel ratio even though the air pressure drops and the total airtight density decreases. In order to achieve this, the final fuel injection spear Qf must be reduced, and therefore Kf and Kg are reduced. Figure 4 shows the learning value K
It shows the relationship between g and atmospheric pressure Pa. The learned value Kg decreases as the atmospheric pressure Pa decreases, and the learned value Kg and the atmospheric pressure Pa
It can be seen that there is a mutual functional relationship.

FIG. 5 is a functional block diagram of the present invention. The target deep rotational speed calculation means 86 calculates the target engine rotational speed Ne' of the engine. FIG. 6 shows the relationship between the throttle opening degree O and the target engine rotational speed Ne' in steady state. Thrower 1
- Set the required output horsepower of the engine as a function of the opening degree of 0,
Each required output horsepower is calculated by the minimum fuel consumption rate (unit + g/psh
) is set as the engine rotation speed Ne'. The flow rate control valve production 1 voltage calculation means 88 calculates the target engine rotational speed Ne'
, CVTIO input side rotation speed N1n (-=Ji% rotation speed Nc), and output side exit I station speed Nout (c/
- Calculate the control voltage f of the flow rate control valve 38 from the heavy speed V). To explain in detail, the target speed ratio e' is set to e'==No
Calculate from ut/Ne' and calculate the actual speed ratio e as e=Nou
It is calculated from t/Nin, and the control voltage f is changed based on the deviation Δe=e'-e between the target speed ratio e' and the actual speed ratio e. In this way, the engine rotational speed Ne is feedback-controlled through the control 1 of the speed ratio e of the CVTIO. The basic engine torque calculating means 9o calculates the basic value Tb of the engine torque from the thrower 1 hell opening degree 0 and the engine rotational speed Ne.

FIG. 7 shows the relationship between the engine rotational speed Ne, the throttle opening degree 0, and the basic value Tb of the engine torque. Basic value T
b is set as engine 1-lux corresponding to a throttle opening of 0 at the original car pressure on a flat ground. When the air density decreases as the vehicle travel altitude increases, the engine torque at the same throttle opening decreases. The learning value calculation means 92 calculates the learning value l(g) according to the flowchart in FIG. 3. The torque correction coefficient calculation means 94 calculates the correction coefficient Kt from the learning value Kg. FIG. The relationship is shown. The atmospheric pressure Pa can be calculated as a function F (K g) of the learning value Kg, and therefore the torque correction coefficient Kt can be calculated as a function of learning (11'L1 (g). The I-luke calculating means 96 calculates the engine torque I'c from Te=Kt・1b. The pressure regulating valve control voltage calculating means 98 calculates the control voltage g of the pressure regulating valve 32 from re-Nin/Nout. It is calculated as a function. Figure 9 shows the control voltage g of the pressure regulating valve '32 and the line pressure 1.
) shows the relationship with l. In relation to the engine torque Te calculated as a function of the learned value Kg, the line pressure 1
] l is controlled, and the belt 26
This prevents the suppressing force of g8 from becoming excessive.
Problems such as deterioration of batting consumption efficiency and loss of life of Bell 1 to 26 are prevented.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the entire cv'r to which the present invention is applied;
Fig. 2 is a block diagram of the electronic control unit 1H, Fig. 3 is a flowchart of the learned value "1Φ routine" for air-fuel ratio control, and Fig.
Figure 5 is a graph showing the relationship between learned value and atmospheric pressure, Figure 5 is a functional block diagram of the present invention, Figure 6 is a graph showing the relationship between throttle opening and target engine speed in steady state, and Figure 7
The figure shows the basic value of engine torque, engine rotation speed, and thrower 1.
FIG. 8 is a graph showing the relationship between atmospheric pressure and torque correction coefficient, and FIG. 9 is a graph showing the relationship between pressure regulating valve control voltage and line pressure. 10 - CVT, 22a, 22b - input end pulley, 24a, 24b... output side pulley, 26... belt, 32... pressure regulating valve, 92... learning value calculation means,
94...1-Luke correction coefficient calculation means, 96... Engine torque calculation means. Fig. 1 10 te zi+a Otokan υ Fig. 2 Fig. 3 Learned value 9 Fig. 6 Throttle opening θ Fig. 7 Engine rotation speed Ne

Claims (1)

[Scope of Claims] 1) A dual-use engine in which engine power is transmitted from the input pulley to the output pulley via a belt, and the belt pressing force by either the input pulley or the output pulley is controlled by line pressure. (If
For line pressure control devices for continuously variable transmissions for vehicles, which are characterized by . 2. Claims characterized in that the feedback correction ii for fuel injection during the air-fuel ratio feedback control period of the engine is detected, and the line pressure is controlled in relation to this feedback correction amount that has a mutual functional relationship with the atmospheric pressure. The line pressure control device according to item 1. 3 Taking the engine torque at the standard atmospheric pressure as the basic value, calculate this basic value from the throttle opening and the engine rotational speed, calculate the engine torque using the calculated basic value and the feedback correction amount, and calculate this basic value. 3. The line pressure control device according to claim 2, wherein the line pressure is controlled in relation to engine torque.