JP2010216490A - Belt slip ratio computing device for v-belt type continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform computing without newly providing a sensor by using the only detection value of an existing pulley rotation sensor when computing a V-belt slip ratio. <P>SOLUTION: When the highest change gear ratio selecting condition is determined in S21, a non-load and highest time pulley rotation ratio λo stored when delivering from a factory is read in S22, and the real pulley rotation ratio λ=Npri/Nsec is computed based on the present number of rotation Npri of a primary pulley and the number of rotation Nsec of a secondary pulley in S23, and the highest time belt slip ration SLip=ä(λ-λo)/λo}×100% is computed in S24. In S25, a deviation ΔSLip between the belt slip ratio SLip and the highest time target belt slip ratio SLip* is obtained. In S26 and S27, the target primary pulley pressure Ppri* to be required to obtain ΔSLip=0 by maintaining the highest change gear ratio is obtained, and a drive duty for making the line pressure P<SB>L</SB>to be used as it is as the primary pulley pressure Ppri coincides with the target primary pulley pressure Ppri* is output to a line pressure control valve. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a belt slip ratio calculating device for a V belt type continuously variable transmission that calculates a belt slip ratio as a guide for determining what slip state the V belt of the V belt type continuously variable transmission is in with respect to the pulley. It is about.

The V-belt type continuously variable transmission is configured by spanning a V-belt between a primary pulley on the input side and a secondary pulley on the output side.
In order to enable shifting, the primary pulley and the secondary pulley can each be stroked in the axial direction by the individual pulley pressure with respect to one fixed flange forming the pulley V groove.

In shifting control, one of these pulley pressures is controlled to determine the V belt clamping pressure by the primary pulley and the V belt clamping pressure by the secondary pulley,
The gear ratio of the V belt type continuously variable transmission is determined by the correlation between the V belt clamping pressure by the primary pulley and the V belt clamping pressure by the secondary pulley.

  By the way, the V belt type continuously variable transmission needs to determine the V belt clamping pressure by the primary pulley pressure and the V belt clamping pressure by the secondary pulley pressure so that the slip ratio of the V belt with respect to the primary pulley and the secondary pulley becomes appropriate. There is.

Incidentally, when the V belt clamping pressure due to the primary pulley pressure and the V belt clamping pressure due to the secondary pulley pressure are too small and the V belt is excessively slipping, not only the transmission efficiency is lowered, but the durability of the V belt is deteriorated,
Conversely, when the V-belt clamping pressure due to the primary pulley pressure and the V-belt clamping pressure due to the secondary pulley pressure are too large and the V-belt is insufficiently slipped, not only does the durability of the V-belt deteriorate, but the V-belt clamping pressure The problem is that the power loss is increased by an excessive amount and the fuel consumption is deteriorated.

Therefore, it is necessary to control the V belt clamping pressure by the primary pulley pressure and the V belt clamping pressure by the secondary pulley pressure so that the belt slip ratio of the V belt with respect to the primary pulley and the secondary pulley becomes appropriate.
Therefore, it is necessary to calculate the belt slip ratio of the V belt with respect to the primary pulley and the secondary pulley.

For example, in view of such a requirement, a technique as described in Patent Document 1 is conventionally known as a technique for calculating a belt slip ratio.
In the belt slip ratio calculation technique described here, a detection point on the V belt is detected by a non-contact sensor provided at an intermediate position between the primary pulley and the secondary pulley, and the interval of the detection is monitored to detect the V belt. The speed of the V belt is directly obtained by directly detecting the speed, and the belt slip ratio is calculated using the speed of the V belt.

Japanese Patent Laid-Open No. 03-222234

However, if the belt slip ratio is calculated as described above, it is necessary to additionally install a dedicated non-contact type sensor that directly detects the speed of the V belt at an intermediate position between the primary pulley and the secondary pulley. ,
Not only is it disadvantageous in terms of cost and also causes an increase in weight, but the non-contact type sensor and its mounting structure must be installed in a limited space, and the layout of additional parts, There is also a problem that it is difficult to secure the installation space.

In view of the above problems, the present invention provides a belt slip ratio calculation device capable of calculating a belt slip ratio without adding any new parts,
Specifically, the belt slip ratio can be calculated based on the primary pulley rotation speed and secondary pulley rotation speed detected by the primary pulley rotation sensor and the secondary pulley rotation sensor existing in the V-belt type continuously variable transmission for shift control. Proposed belt slip ratio calculation device
Thereby, it aims at solving the above-mentioned problems.

For this purpose, the belt slip ratio calculating device for a V-belt type continuously variable transmission according to the present invention constitutes the same as described in claim 1.
First, to explain a V-belt type continuously variable transmission using the belt slip ratio calculating device of the present invention,
A V-belt is provided between the primary pulley on the input side and the secondary pulley on the output side, and the gear ratio is determined by the correlation between the V-belt clamping pressure by the primary pulley and the V-belt clamping pressure by the secondary pulley.

The belt slip ratio computing device of the present invention is such a V-belt continuously variable transmission,
No-load pulley rotation ratio between the primary pulley rotation speed and the secondary pulley rotation speed when the input torque to the primary pulley is zero under a specific gear ratio,
From the actual pulley rotation ratio between the current primary pulley rotation speed and the secondary pulley rotation speed under the same gear ratio as the specific speed ratio,
The slip ratio of the V belt with respect to the primary pulley and the secondary pulley is calculated.

According to the belt slip ratio calculating apparatus of the present invention, although it is for each gear ratio, the unloaded pulley rotation ratio between the primary pulley rotation speed and the secondary pulley rotation speed at no load, the current primary pulley rotation speed, and In order to calculate the slip ratio of the V belt from the actual pulley rotation ratio between the secondary pulley rotation speeds,
The belt slip ratio is calculated based on the primary pulley rotation speed and the secondary pulley rotation speed detected by the primary pulley rotation sensor and the secondary pulley rotation sensor existing in the V-belt type continuously variable transmission for shift control.

Therefore, when calculating the belt slip ratio, this calculation can be performed without adding any new parts, which is advantageous in terms of cost and does not cause a problem of increasing the weight.
In addition, since there is no need to add new parts, there is a problem in terms of layout and the problem of securing the installation space that the device itself and its mounting structure must be installed in a limited space. There is no.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram illustrating a V-belt continuously variable transmission to which a belt slip ratio calculating device according to the present invention can be applied, together with its shift control system. FIG. 2 is a detailed front view showing a V-belt winding transmission portion of the V-belt type continuously variable transmission in FIG. 1 in a highest gear ratio selection state. It is a block diagram which shows the detail of the transmission control system in FIG. FIG. 4 is a flowchart showing a control program for a no-load & highest pulley rotation ratio memory process executed by the transmission controller in FIGS. 4 is a flowchart showing a control program for highest belt slip ratio calculation processing and pulley pressure (V belt clamping pressure) control processing executed by the transmission controller in FIGS. FIG. 6 is a relationship diagram between a belt slip ratio, a pulley and a belt-to-belt friction coefficient, showing a maximum belt slip ratio control area according to the embodiment of FIGS. 1 to 5 in comparison with a conventional belt slip ratio control area.

Hereinafter, embodiments of the present invention will be described in detail based on an example shown in the drawings.
<Configuration>
FIG. 1 schematically shows an example of a V-belt type continuously variable transmission 1 to which a belt slip ratio calculating device of the present invention can be applied.
This V-belt type continuously variable transmission 1 has a primary pulley 2 and a secondary pulley 3 arranged so that both pulley V grooves are aligned in a plane perpendicular to the axis, and the endless V in the V grooves of these pulleys 2 and 3 is provided. The belt 4 is stretched and generally configured.

  An engine 5 is disposed coaxially with the primary pulley 2, and a lockup torque converter 6 and a forward / reverse switching mechanism 7 are interposed between the engine 5 and the primary pulley 2 in order from the engine 5 side.

The forward / reverse switching mechanism 7 has a double pinion planetary gear set 7a as a main component, and its sun gear is connected to the engine 5 via the torque converter 6 to be an input element, and the carrier is connected to the primary pulley 2 to be an output element. Eggplant.
The forward / reverse switching mechanism 7 further includes a forward clutch 7b that directly connects the sun gear and the carrier of the double pinion planetary gear set 7a, and a reverse brake 7c that fixes the ring gear.

Thus, when the forward / reverse switching mechanism 7 releases both the forward clutch 7b and the reverse brake 7c, it becomes a neutral state in which the input rotation from the engine 5 via the torque converter 6 is not transmitted to the primary pulley 2, and in this state,
When the forward clutch 7b is engaged, the input rotation from the engine 5 via the torque converter 6 is directly transmitted to the primary pulley 2 as the forward rotation.
When the reverse brake 7c is engaged, the input rotation via the torque converter 6 from the engine 5 can be transmitted to the primary pulley 2 as reverse rotation under reverse deceleration.

The rotation to the primary pulley 2 is transmitted to the secondary pulley 3 via the V-belt 4, and the rotation of the secondary pulley 3 is thereafter passed through the output shaft 8, the final reduction gear set 9 and the differential gear device 10 coupled to the secondary pulley 3. It reaches left and right drive wheels (not shown) and is used for traveling of the vehicle.
In order to make it possible to change the rotational transmission ratio (speed ratio) between the primary pulley 2 and the secondary pulley 3 during the power transmission described above, one of the opposing flanges forming the V-grooves of the primary pulley 2 and the secondary pulley 3 is fixed. The flanges 2a and 3a are used, and the other flanges 2b and 3b are movable flanges that can be displaced in the axial direction.

These movable flanges 2b and 3b are respectively supplied with a primary pulley pressure Ppri and a secondary pulley pressure Psec having a line pressure controlled in detail as will be described later as a primary pressure, to the primary pulley chamber 2c and the secondary pulley chamber 3c. Energize toward the fixing flanges 2a and 3a.
As a result, the V-belt 4 is clamped between the opposed flanges 2a, 2b and 3a, 3b to enable the power transmission between the primary pulley 2 and the secondary pulley 3.

The V-belt 4 that controls this power transmission is constructed in a belt shape by connecting a number of V-shaped elements 4a as shown in FIG. 1 with endless bands (not shown) as shown in FIG. As shown in FIG. 1, 4a is clamped between the opposing flanges 2a, 2b and 3a, 3b to transmit power between the primary pulley 2 and the secondary pulley 3.
2 shows the highest gear ratio selection state in which the winding radius of the V belt 4 with respect to the primary pulley 2 is maximized and the winding radius of the V belt 4 with respect to the secondary pulley 3 is minimized.

<Shifting action>
At the time of shifting, the differential pressure between the secondary pulley pressure Psec generated corresponding to the target gear ratio and the primary pulley pressure Ppri that uses the line pressure as it is, with the line pressure to be controlled as described later as the source pressure, is used. The target gear ratio can be realized by changing the V groove widths of the pulleys 2 and 3 and continuously changing the winding radius of the V belt 4 around the pulleys 2 and 3.

The outputs of the primary pulley pressure Ppri and the secondary pulley pressure Psec are output by the shift control hydraulic circuit 11 together with the engagement hydraulic pressure output of the forward clutch 7b to be engaged when the forward travel range is selected and the reverse brake 7c to be engaged when the reverse travel range is selected. To control.
The shift control hydraulic circuit 11 performs the control in response to a signal from the transmission controller 12.

  For this reason, the transmission controller 12 receives a signal from the primary pulley rotation sensor 13 that detects the primary pulley rotation speed Npri, a signal from the secondary pulley rotation sensor 14 that detects the secondary pulley rotation speed Nsec, and the secondary pulley pressure Psec. A signal from the secondary pulley pressure sensor 15 to detect, a signal from the primary pulley pressure sensor 16 to detect the primary pulley pressure Ppri, a signal from the accelerator opening sensor 17 to detect the accelerator pedal depression amount APO, and an inhibitor switch 18 And a signal (engine speed, fuel injection time, etc.) relating to transmission input torque (including no-load information with torque 0) from the engine controller 19 that controls the engine 5 .

The shift control hydraulic circuit 11 and the transmission controller 12 are as shown in FIG. 4. First, the shift control hydraulic circuit 11 will be described below.
The shift control hydraulic circuit 11 comprises an oil pump 21 driven by the engine, from which the medium of the hydraulic oil to the oil passage 22, which pressure is regulated to a predetermined line pressure P _L by the pressure regulator valve 23.
The line pressure P _L in the oil passage 22 on the one hand and supplied to the primary pulley chamber 2c as the primary pulley pressure Ppri as it is, is supplied to the secondary pulley chamber 3c as the secondary pulley pressure Psec after being pressure regulated by the shift control valve 25 on the other hand .
Note the pressure regulator valve 23 shall be controlled so that the line pressure P _L by the drive duty input into a solenoid 23a, a higher pressure corresponding to the transmission input torque.

The speed change control valve 25 has a neutral position 25a, a pressure increase position 25b, and a pressure reduction position 25c. The speed change control valve 25 is connected to the middle of the speed change link 26 in order to switch these valve positions. A step motor 27 as a speed change actuator is connected to one end of 26, and a movable flange 2b of a secondary pulley is connected to the other end.
The step motor 27 is moved from the reference position to the operation position advanced by the number of steps corresponding to the target gear ratio, and the operation of the step motor 27 causes the speed change link 26 to swing around the connecting portion with the movable flange 2b. As a result, the shift control valve 25 is moved from the neutral position 25a to the pressure increasing position 25b or the pressure reducing position 25c.

In the neutral position 25a of the shift control valve 25, the secondary pulley pressure Psec is pressure retention, the pressure increasing position 25b of the shift control valve 25, the secondary pulley pressure Psec is boosted to the line pressure P _L as source pressure, the shift control valve At the 25 decompression position 25c, the secondary pulley pressure Psec is decompressed by the drain.
If the differential pressure between the secondary pulley pressure Psec and the primary pulley pressure Ppri changes due to the above increase / decrease of the secondary pulley pressure Psec, the V-belt continuously variable transmission 1 is downshifted to the low gear ratio when the secondary pulley pressure Psec is increased. When the secondary pulley pressure Psec is reduced, the V-belt continuously variable transmission 1 is upshifted to the high gear ratio, and the V-belt continuously variable transmission 1 can be shifted toward the target gear ratio. it can.

The progress of the speed change is fed back to the corresponding end of the speed change link 26 via the movable flange 3b of the secondary pulley 3, and the speed change link 26 is connected to the step motor 27 as a fulcrum and the speed change control valve 25 is set to the pressure increasing position. It swings in a direction to return to the neutral position 25a from 25b or the decompression position 25c.
Thus, when the target speed ratio is achieved, the speed change control valve 25 is returned to the neutral position 25a, and the V-belt type continuously variable transmission 1 can be maintained at the target speed ratio by maintaining the secondary pulley pressure Psec.

  The solenoid drive duty of the pressure regulator valve 23 and the shift command (step number Step) to the step motor 27 are controlled with whether or not the engagement hydraulic pressure is supplied to the forward clutch 7b and the reverse brake 7c shown in FIG. These are determined by the controller 12.

In the duty control of the pressure regulator valve 23, the transmission controller 12 uses a transmission input torque Ti obtained based on input torque related information (engine speed, fuel injection time, etc.) from the engine controller 19 (see FIG. 1), The belt slip ratio of the V belt 4 with respect to the primary pulley 2 and the secondary pulley 3 calculated as described later can be transmitted from the transmission input torque Ti from the viewpoint of durability and transmission efficiency of the V belt 4. best to the line pressure P _L (target V-belt clamping force of the primary pulley 2 and secondary pulley 3) target belt slip ratio required target primary pulley pressure to become match, drives the solenoid 23a of pressure regulator valve 23 Determine the duty.

In controlling whether to supply the engagement hydraulic pressure to the forward clutch 7b and the reverse brake 7c shown in FIG. 1, the transmission controller 12 performs the control in accordance with the selection range signal from the inhibitor switch 18 as follows.
If the V-belt type continuously variable transmission 1 is set to a non-traveling range such as a P (parking) range or an N (stopping) range, the forward clutch 7b and the reverse brake 7c are not supplied with fastening hydraulic pressure, and these forward clutches By releasing 7b and reverse brake 7c, V belt type continuously variable transmission 1 is brought into a neutral state where no power is transmitted.

If the V-belt type continuously variable transmission 1 is set to the forward travel range such as the D range, the engagement hydraulic pressure is supplied only to the forward clutch 7b, and the V-belt type continuously variable transmission 1 is transmitted to the forward rotation by the engagement. To be in a state.
If the V-belt type continuously variable transmission 1 is set to the reverse travel range such as the R range, the engagement hydraulic pressure is supplied only to the reverse brake 7c, and the V belt type continuously variable transmission 1 is transmitted to the reverse rotation by the engagement. To be in a state.

When determining the gear shift command (step number Step) to the step motor 27, the transmission controller 12 determines the target based on the planned shift map from the vehicle speed VSP obtained from the secondary pulley rotation speed Nsec and the accelerator opening APO. A gear ratio is obtained, and the step number Step corresponding to this is used as a gear shift command.
The step motor 27 shown in FIG. 3 makes the actual speed ratio of the V-belt type continuously variable transmission 1 coincide with the target speed ratio by the speed change action in response to the speed change command (step number Step).

<Calculation of belt slip ratio>
As described above, during the transmission of the V-belt type continuously variable transmission 1, the belt slip ratio of the V belt 4 with respect to the primary pulley 2 and the secondary pulley 3 is the optimum target belt slip from the viewpoint of the durability of the V belt 4 and the transmission efficiency. so as to be rate, it is necessary to control the V-belt clamping pressure by the primary pulley 2 and secondary pulley 3 via the control of the line pressure P _L (pulley pressure Ppri, control of Psec).

  For this purpose, the transmission controller 12 of FIGS. 1 and 3 performs the arithmetic processing shown by the flowcharts of FIGS. 4 and 5, and the belt slip ratio SLip of the V belt 4 with respect to the primary pulley 2 and the secondary pulley 3 will be described in detail later. And the pulley pressures Ppri and Psec (the V belt clamping pressure by the primary pulley 2 and the secondary pulley 3) are controlled based on the belt slip ratio SLip as described in detail later.

  In calculating the belt slip ratio SLip, first, for example, when the vehicle is shipped from the factory, the control program of FIG. 4 is executed, and the no-load & highest pulley rotation ratio λo is obtained and stored as follows.

In step S11, it is checked whether or not the V-belt continuously variable transmission 1 is in a selected gear ratio (here, the highest gear ratio shown in FIG. 2) is selected.
If the V-belt type continuously variable transmission 1 is not in the highest gear ratio selection state, it is not a specific gear ratio (highest gear ratio) for calculating the belt slip ratio SLip. Calculation of the highest pulley rotation ratio λo and its memory are not performed.

When it is determined in step S11 that the V-belt type continuously variable transmission 1 is in a specific gear ratio (highest gear ratio) selection state, in step S12, the engine 5 is now in an unloaded state with zero output torque. Check whether or not.
If the engine 5 is not in a no-load state, there is no condition for calculating the no-load & highest pulley rotation ratio λo, so control is terminated and the no-load & highest pulley rotation ratio λo is calculated. And do not do that memory.

  When it is determined in step S11 that the V-belt type continuously variable transmission 1 is in a specific gear ratio (highest gear ratio) selection state and in step S12 it is determined that the engine 5 is in an unloaded state, In step S13, the no-load & highest pulley rotation ratio λo is obtained by calculating λo = Npri / Nsec from the primary pulley rotation speed Npri and the secondary pulley rotation speed Nsec at this time.

  In the next step S14, the unloaded & highest pulley rotation ratio λo calculated as described above is stored in memory for calculating a belt slip ratio SLip described later.

  After the vehicle is shipped from the factory, the transmission controller 12 shown in FIGS. 1 and 3 executes the control program shown in FIG. 5 to calculate the highest belt slip ratio SLip as follows, and this highest belt slip. Control of pulley pressures Ppri and Psec (V belt clamping pressure by primary pulley 2 and secondary pulley 3) based on rate SLip is performed as described later.

First, in step S21, it is checked whether or not the V-belt type continuously variable transmission 1 is in a state where the highest gear ratio that is the same as the specific gear ratio is selected.
If the V belt type continuously variable transmission 1 is not in the highest gear ratio selection state, it is not a specific gear ratio (highest gear ratio) for calculating the highest belt slip ratio SLip. The highest belt slip ratio SLip is not calculated.

When it is determined in step S21 that the V-belt type continuously variable transmission 1 is in the highest gear ratio selection state, the control proceeds to step S22 and thereafter, and the highest belt slip ratio SLip is calculated as follows. .
In step S22, as described above with reference to FIG. 4, the no-load & highest pulley rotation ratio λo stored at the time of shipment from the factory is read.

In the next step S23, the current actual pulley rotation ratio λ is obtained by calculating λ = Npri / Nsec from the current primary pulley rotation speed Npri and the secondary pulley rotation speed Nsec read this time.
Next, in step S24, the highest belt slip ratio SLip is calculated from the no-load & highest pulley rotation ratio λo read in step S22 and the current actual pulley rotation ratio λ calculated in step S23. SLip = {(λ -Λo) / λo} × 100%.

  The reason why the current actual pulley rotation ratio λ is the highest at the same specific gear ratio as the unloaded & highest pulley rotation ratio λo is as described above. When the belt slip ratio SLip is obtained using the pulley rotation ratio λ, the obtained belt slip ratio SLip differs depending on the gear ratio of the V-belt continuously variable transmission 1, and the no-load pulley rotation ratio λo and the load pulley rotation This is because the ratio λ needs to be the same gear ratio.

<Belt clamping pressure control>
The transmission controller 12 in FIGS. 1 and 3 uses the maximum belt slip ratio SLip obtained as described above in steps S22 to S24 in FIG. 5, and the following pulley pressures in steps S25 to S27 in FIG. Ppri, Psec (V belt clamping pressure by primary pulley 2 and secondary pulley 3) is controlled.

  In step S25, a belt slip ratio deviation ΔSLip between the highest belt slip ratio SLip * at the highest time and the highest belt slip ratio SLip calculated in step S24 is obtained.

Here, the highest belt slip ratio SLip * is described.
In the V-belt continuously variable transmission 1, the friction coefficient μeff between the pulleys 2 and 3 and the V-belt 4 changes with a tendency as illustrated in FIG. 6 with respect to the belt slip ratio SLip.
In FIG. 6, the positive polarity indicates the characteristic during forward rotation transmission, and the negative polarity indicates the characteristic during reverse rotation transmission.

Conventionally, the pulley pressures Ppri, Psec (primary) are set so that the belt slip ratio SLip is maintained near zero, including when the highest gear ratio is selected, that is, the belt slip ratio control region is the region indicated by A in FIG. V belt clamping pressure by the pulley 2 and the secondary pulley 3) was controlled.
However, in this case, although there is a belt slip ratio region in which the friction coefficient μeff between the pulleys 2 and 3 and the V belt 4 is larger and the transmission efficiency can be improved, this region is not effectively utilized. Become.

Therefore, in this embodiment, when the highest gear ratio that requires high transmission efficiency is selected, the belt slip ratio control region is as shown in FIG. 6B so that the friction coefficient μeff is large, that is, the belt slip ratio. For example, in order to maintain SLip at a value as shown by SLip * in FIG.
In step S25, a belt slip ratio deviation ΔSLip between the highest belt slip ratio SLip * and the highest belt slip ratio SLip is obtained.

  In step S26 of FIG. 5, it is necessary to maintain the highest gear ratio and make the belt slip ratio deviation ΔSLip 0, that is, the belt belt with the highest slip ratio SLip when the highest gear ratio is selected. The highest belt slip ratio SLip (belt slip ratio deviation ΔSLip) fed back to the target primary pulley pressure Ppri * (target V-belt clamping pressure of the primary pulley 2 and secondary pulley 3) required to become the slip ratio SLip * PID (P: proportional control, I: integral control, D: derivative control) based on the calculation.

In the next step S27, it is used the line pressure P _L as a street primary pulley pressure Ppri described above is the driving duty of the line pressure control to match the target primary pulley pressure Ppri * determined in as described above in step S26 The driving duty is output to the solenoid 23a of the pressure regulator valve 23.

According to your according upon HIGHEST line pressure, the line pressure P _L to keep the belt slip ratio SLip to HIGHEST time target belt slip ratio SLip * becomes to be feedback-controlled, the belt slip ratio during HIGHEST speed ratio selection The control region can be a region having a large friction coefficient μeff, indicated by B in FIG.
Thus, the transmission efficiency of the V-belt type continuously variable transmission 1 can be improved by maintaining the belt slip ratio region in which the friction coefficient μeff is large.

Note the HIGHEST time target belt slip ratio SLip * as shown in FIG. 6, the friction coefficient be of large areas of .mu.eff, to determine the smallest belt slip ratio of them, the line pressure P _{L (the} primary pulley pressure Ppri ) Is not increased more than necessary, and the deterioration of fuel consumption due to this is more than compensated by the improvement of the transmission efficiency.

<Effects of illustrated example>
According to the illustrated example described above, although the highest gear ratio is selected, the no-load pulley rotation ratio λo between the primary pulley rotation speed and the secondary pulley rotation speed when there is no load, the current primary pulley rotation speed and the secondary rotation speed In order to obtain the slip ratio SLip of the V-belt 4 from the actual pulley rotation ratio λ between the pulley rotation speeds by calculating SLip = {(λ−λo) / λo} × 100%,
The belt slip ratio SLip is calculated based on the primary pulley rotation speed Npri and the secondary pulley rotation speed Nsec detected by the existing primary pulley rotation sensor 13 and secondary pulley rotation sensor 14 in the V-belt continuously variable transmission 1 for shift control. Can be done.

Therefore, when calculating the belt slip ratio SLip, this calculation can be performed without adding any new parts, which is advantageous in terms of cost and does not cause a problem of increasing the weight.
In addition, since there is no need to add new parts, there is a problem in terms of layout and the problem of securing the installation space that the device itself and its mounting structure must be installed in a limited space. There is no.

Further, when the line pressure P _L (the V belt clamping pressure of the primary pulley 2 and the secondary pulley 3) is feedback-controlled so that the belt slip ratio SLip obtained as described above is maintained at the target belt slip ratio SLip *, the target Since the belt slip ratio SLip * is set to the minimum value in the region where the friction coefficient μeff is large as shown in FIG.
The friction coefficient between the primary pulley 2 and the secondary pulley 3 and the V-belt 4 is increased, so that the transmission efficiency of the V-belt type continuously variable transmission 1 can be improved and the fuel efficiency of the V-belt clamping pressure is increased. Deterioration can be compensated for by the improvement of the transmission efficiency, and can be made slightly small.

<Modification>
In the above embodiment, only the calculation procedure of the belt slip ratio SLip and the V belt clamping pressure control when the highest gear ratio is selected have been described, but the specific gear ratio may be a gear ratio other than the highest gear ratio. .
The specific gear ratio need not be only one gear ratio, and may be any number of gear ratios. In this case, the calculation of the belt slip ratio SLip and the V belt clamping pressure control are performed for each gear ratio. It goes without saying that this is done in the same way as.
Furthermore, it goes without saying that the target belt slip rate SLip * can be arbitrarily determined for each specific gear ratio in the V belt clamping pressure control.

1 V belt type continuously variable transmission
2 Primary pulley
2a Fixed flange
2b Movable flange
2c Primary pulley pressure chamber
3 Secondary pulley
3a Fixed flange
3b Movable flange
3c Secondary pulley pressure chamber
4 V belt
5 Engine
6 Lock-up torque converter
7 Forward / reverse switching mechanism
8 Output shaft
9 Final reduction gear set
10 Differential gear unit
11 Shift control hydraulic circuit
12 Transmission controller
13 Primary pulley rotation sensor
14 Secondary pulley rotation sensor
15 Secondary pulley pressure sensor
16 Primary pulley pressure sensor
17 Accelerator position sensor
18 Inhibitor switch
19 Engine controller
21 Oil pump
23 Pressure regulator valve
25 Shift control valve
26 Speed change link
27 Step motor (shifting actuator)

Claims (3)

A V-belt type continuously variable V belt is provided between the primary pulley on the input side and the secondary pulley on the output side, and the gear ratio is determined by the correlation between the V belt clamping pressure by the primary pulley and the V belt clamping pressure by the secondary pulley. In the transmission,
No-load pulley rotation ratio between the primary pulley rotation speed and the secondary pulley rotation speed when the input torque to the primary pulley is zero under a specific gear ratio,
From the actual pulley rotation ratio between the current primary pulley rotation speed and the secondary pulley rotation speed under the same gear ratio as the specific speed ratio,
A belt slip ratio calculating device for a V-belt type continuously variable transmission, wherein the slip ratio of the V belt with respect to the primary pulley and the secondary pulley is calculated. In the belt slip ratio calculating device of the V belt type continuously variable transmission according to claim 1,
A belt slip ratio calculating device for a V-belt type continuously variable transmission, wherein the specific gear ratio is a highest gear ratio on a high speed side of the V-belt type continuously variable transmission. In the belt slip ratio calculating device of the V belt type continuously variable transmission according to claim 1 or 2,
The belt slip ratio is calculated by dividing a pulley rotation ratio deviation between the no-load pulley rotation ratio and the actual pulley rotation ratio by a no-load pulley rotation ratio. Belt slip ratio calculation device.

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