JPS6131752A - Device for controlling continuously variable trans mission for vehicle - Google Patents

Abstract

PURPOSE:To improve the power performance and drivability of a vehicle by providing an auxiliary transmission having at least forward 2 stages in series to a belt system continuously variable transmission to set a desired rotational speed of an engine according to the speed change stage of the auxiliary transmission. CONSTITUTION:An auxiliary forward 2 stage transmission 42 is connected in series to a belt system continuously variable transmission (CVT) 1. In this transmission, the shift range is judged by a shift position sensor and a desired rotational speed of an engine is set according to this shift range so that the desired high rotational speed of the engine will be set when the auxiliary transmission is in the low speed range, and the desired low one will be set when the auxiliary transmission is in the high speed range. Thus, the speed change ratio of the whole transmission is enlarged so that drive torque is increased to provide satisfactory power performance and drivability.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a continuously variable transmission for a vehicle (hereinafter referred to as a "pre-speed transmission") which is provided in series with an auxiliary transmission that changes gears in relation to a shift range. (The machine Δ is referred to as l CVT J.).

Prior Art In Japanese Patent Application No. 58-144985, the present applicant proposes to improve the power performance of a vehicle equipped with a CVT by providing an auxiliary transmission with multiple forward speeds in series with the CVT in the power transmission path of the engine. Disclosed.

, Fig. 7 shows the relationship between the vehicle speed ■ and the engine rotation speed Ne when an auxiliary transmission that can change gears in relation to the L (low) range and the D (drive) range is provided. . Note that ellaX+emln is the CVT speed ratio e (e = Nout/Nin, where Nout
+N1n are the maximum and minimum values of the output side and input side rotational speeds of the CVT, respectively. The gear position of the auxiliary transmission is changed in relation to the shift range, but in conventional CV
In the T control device, the target engine rotation speed is not changed depending on the shift range, so if the vehicle speed and the intake throttle opening are equal, the target engine rotation speed is set to the same value regardless of the shift range. In other words, even if there is a shift range from D range to L range within the shaded area in Fig. 7, the change in the gear ratio of the auxiliary transmission is offset by the change in the gear ratio (=l/e) of the CVT. To put it away,
There is a problem that the gear ratio of the entire power transmission device including the CVT and the auxiliary transmission does not change, and the effect of shifting from the D range to the L range does not occur.

Problems to be Solved by the Invention It is an object of the present invention to
An object of the present invention is to provide a CVT starvation device that can improve power performance and drivability by appropriately controlling the CVT.

Means for Solving the Problems In order to achieve this object, according to the present invention, a CVT is provided in series with an auxiliary transmission having two or more forward gears, and the gears of the auxiliary transmission are In a vehicle CVT control device in which the CVT speed ratio is changed in relation to the shift range and the speed ratio of the CVT is controlled so that the engine rotation speed becomes a target engine rotation speed, the target engine rotation speed is set in relation to the shift range. A setting means is provided.

Effects of the Invention In the present invention, the target engine rotation speed is set in relation to the shift range, and as a result, the target engine rotation speed is selected in accordance with the gear stage of the auxiliary transmission.

In this way, even within the shaded area in FIG. 7, the gear ratio of the entire power transmission device can be set to an appropriate value in relation to the shift range, and power performance and drivability can be improved.

Preferably, the target engine speed is a function of intake throttle opening and vehicle speed.

Preferably, the auxiliary transmission is set to a low speed in the low range, and the target engine rotation speed in the low range is set to a higher value than the target engine rotation speed in the drive range.

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

FIG. 1 illustrates the entire power transmission system having a CVT and an auxiliary transmission in series, and CvTl is a pair of input sheaves 2a+2b and 11 pairs of output sheaves 4a+4.
b % and input side sheave 2a+2b and output side sheave 4
V-belt 6 that is hung between a+4b and transmits engine power
It is equipped with One input side sheave 2a is provided on the input shaft 8 so as to be movable in the axial direction and fixed in the rotational direction, and the other input side sheave 2b is provided fixedly on the input shaft 8. Also, one output side sheave 4a is the output shaft I
The other output side sheave 4b is provided on the output shaft 10 so as to be movable in the axial direction and fixed in the rotational direction. The facing surfaces of the input side sheaves 2a + 2b and the facing surfaces of the output side sheaves 4a and 4b are formed in a tapered shape such that the mutual distance increases radially outward, and the cross section of the V belt 6 has an isosceles trapezoidal shape. is formed. The pressing force of the output side sheaves 4a, 4b is controlled to the minimum value that can avoid slipping of the V belt 6 and ensure power transmission, and the pressing force of the input side sheaves 2a, 2b is controlled to the speed ratio e of the CVT 1.
(=rotational speed Nout of output shaft lO/rotational speed Nin of input shaft 8) is determined. A fluid coupling I2 connects a pump 16 connected to the engine crankshaft 14 and a pump 1
a turbine 18 rotated by oil from 6;
and an output shaft 20 connected to the turbine 18. The direct coupling clutch 22 controls the connection between the crankshaft 14 and the output shaft 20, and the damper 24 absorbs torque fluctuations of the surgical site and the engine when the direct coupling clutch is switched from a released state to an engaged state. When the vehicle speed or engine rotational speed exceeds a predetermined value, the direct coupling clutch 22 is held in an engaged state to avoid power transmission loss due to oil in the fluid coupling 12. The oil pump 26 rotates integrally with the pump 16 and pumps oil to the CVT via a hydraulic control device.
1, send to fluid coupling 12. The counter shaft 28 is a CVT
It is provided parallel to the output shaft 10 of I and has two gears 30, 32. The engine power of the output shaft 10 is transferred from the gear 34 on the output shaft 10 to the gear 30 on the counter shaft 28.
32 to the differential gear 36, and from the differential gear 36 to the left and right drive wheels via the left and right axle shafts 38,40.

The auxiliary transmission 42 is provided coaxially with and between the crankshaft 14 and the input shaft 8 of the CVT 1 . The auxiliary transmission 42 includes a Ravigneau type compound planetary gear set 43 , which has first and second sun gears 4 .
4, 46, a first planetary gear 48 meshing with the first sun gear 44;
A second planetary gear 50 meshing with the sun gear 46 of
, a ring gear 52 that meshes with the first planetary gear 48, and a carrier 54 that rotatably supports the first and second planetary gears 48.50. The second sun gear 46 is connected to the output shaft 20 as an input part of the auxiliary transmission 42, and the carrier 54 is connected to the input sheave 2b of the CvT. The high speed clutch 56 controls the connection between the output shaft 20 and the first sun gear 44, the low speed brake 58 controls fixing of the first sun gear 44,
The reverse brake 60 controls fixation of the ring gear 52.

FIG. 2 shows the operating state of each friction engagement element of the auxiliary transmission 42 and the reduction ratio in each range. ◯ means a bonded state, × means a released state, and ρl and ρ2 are defined from the following equations.

p 1 = Zsl / Zr ρ2 = Zs2 / Zr where Zsl is the number of teeth of the first sun gear 44, Zs2 is the number of teeth of the second sun gear 46, and Zr is the number of teeth of the ring gear 52.

As a result of switching the reduction ratio of the auxiliary transmission 42 according to the shift range (the reduction ratio is the reciprocal of the speed ratio), the CVT
The torque transmitted to the first input sheave 2b changes depending on the travel range.

FIG. 3 is a block diagram of the electronic control device.

The address data bus 70 includes a CPU 72 and a RAM 7.
4, ROM 76, I/F (interface) 78
, A/D (analog/digital converter) 80, and D
/A (digital/analog converters) 82 are interconnected. The I/F 78 includes an input side rotation angle sensor 84 that detects the input side rotation speed Nin of the CVT and the CV
It receives pulse signals from an output side rotation angle sensor 86 that detects the output side rotational speed Nout of Tl, and a shift position sensor 88 that detects the shift range. A/D 80
receives analog signals from a water temperature sensor 90 that detects the engine cooling water temperature and a throttle opening sensor 92 that detects the intake throttle opening. D/A 82 sends digital signals to pressure regulating valve 94 and flow control valve 96.

The pressure regulating valve 94 generates line pressure in relation to the input signal;
Line pressure is sent to the output side hydraulic cylinder of CVT 1. The flow control valve 96 controls the flow rate of oil supplied to and discharged from the input hydraulic cylinder of the CVT l in relation to an input signal. CV
When increasing the speed ratio e of T1, the input side hydraulic system 1
When supplying oil to the cylinder and lowering the speed ratio e of CVT I, oil is discharged from the input hydraulic cylinder.

FIG. 4 is a flowchart of the CVT control pattern selection routine. In step 100, an initialization routine is executed. From the initialization process, various data are set to appropriate initial values. In step 102, inputs and necessary data from various sensors are read. At step 104, a control mode is selected from the input and data read at step 102. From the read input and data, if there is an abnormal force on the engine, sensors, etc., execute the fail-safe control in Step 06,
If the engine is starting, execute the cranking @U control in step 108, if the engine is overrunning, execute the overrun division part of step +10, if it is in the neutral range, execute the neutral control in step 112, and in other cases Target engine rotational speed control in step 114 is executed. An appropriate speed ratio e of CVT I is calculated by each control in steps 106 to 114. In the case of overrun control in step 110 and target engine speed control in step +14, line pressure control is also performed in step +16, and an appropriate line pressure Pl is calculated. At step +18, control values corresponding to the calculated values at steps 106 to 116 are output.

FIG. 5 shows the characteristics of the target engine rotational speed No. Target engine rotation speed No is intake throttle opening θ, vehicle speed v1
and is set as a function of shift range. Since the higher the intake throttle opening and the higher the vehicle speed, the higher the engine output is required, the target engine rotational speed NO increases as the intake throttle opening θ and the vehicle speed V increase. Further, the No. of the L range is set to a higher value than the No. of the D range. 4. FIG. 6 is a flowchart of the routine for setting the target engine rotational speed. This routine executes the target engine rotational speed control (step 11) shown in FIG.
Used in 4). Determine the shift range (step 130), if the D range is set as the target engine rotational speed No. C) defined by the solid line in Figure 4, step 132), if the L range is set as the target engine speed No. The L range No. defined by the broken line in the figure is set as the target engine rotational speed No. (step 134). Therefore, in the L range, the auxiliary transmission 42 is in a low gear and the target engine rotational speed No is set to a high value, so the speed ratio e of the CVT decreases, thereby increasing the gear ratio of the power transmission device. Therefore, the driving torque increases and good power performance and drivability are obtained.

Although the present invention has been described with reference to embodiments, it will be apparent to those skilled in the art that various modifications can be made within the spirit of the claims.

[Brief explanation of the drawing]

Fig. 1 is a diagram illustrating the entire power transmission device including a CVT and an auxiliary transmission, Fig. 2 is a chart showing the relationship between the shift range and the operating state of each frictional engagement element, and Fig. 3 is an electronic control A block diagram of the device, FIG. 4 is a flowchart of the CVT control mode selection routine, FIG. 5 is a graph showing the characteristics of the target engine rotational speed, FIG. 6 is a flowchart of the target engine rotational speed setting routine, and FIG. 7 1 is a diagram showing the relationship between vehicle speed, engine rotation speed, etc. in a power transmission device. 1...CVT, 42...auxiliary transmission, 72...c
pu. 88...Shift position sensor. 3rd picture Figure 5 □ D range intake throttle opening θ Figure O

Claims (1)

[Scope of Claims] 1. A continuously variable transmission is provided in series with an auxiliary transmission having two or more forward gears, and the gears of the auxiliary transmission are changed in relation to the shift range to change the engine rotational speed. A control device for a continuously variable transmission for a vehicle in which the speed ratio of the continuously variable transmission is controlled such that the speed ratio of the continuously variable transmission becomes a target engine rotation speed, comprising: setting means for setting the target engine rotation speed in relation to a shift range. A control device for a continuously variable transmission for a vehicle, characterized by: 2. The control device according to claim 1, wherein the target engine rotational speed is a function of intake throttle opening and vehicle speed. 3. Claim 1 or claim 3, characterized in that in the low range, the auxiliary transmission is set to a low gear, and the target engine rotation speed in the low range is set to a higher value than the target engine rotation speed in the drive range. The control device according to item 2.