JPS6362954A - Belt slip detecting method for v-belt type continuously variable transmission - Google Patents

Abstract

PURPOSE:To prevent the proceed of slip of a V-belt and maintain the durability of the V-belt in a V-velt type continuously variable transmission for use with a vehicle transmission, by detecting the slip at an initial stage of generation, and generating a slip signal. CONSTITUTION:When tension of a V-belt 26 leaks to generate slip of the V-belt 26 upon increase in oil temperature, the slip is immediately detected by a belt slip detecting device. That is, an amount of movement of either or both of movable sheaves 24a and 25a is detected to obtain a theoretical pulley ratio. As the rotating speed of a secondary pulley 25 becomes lower than a normal rotating speed, an actual pulley ratio is greater than the theoretical pulley ratio. As a result, there is generated a deviation between both the pulley ratios. When the deviation exceeds a predeteramined value, a slip signal is generated from a slip determining section to detect the generation of the slip of the V-velt 26 at an initial stage. Accordingly, it is possible to take any measures for eliminating the slip such as reducing a transmitting torque of a clutch or increasing a line pressure.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a belt slip detection method in a V-belt continuously variable transmission mainly used in a vehicle transmission.

[Prior Art 1] Regarding the V-belt type continuously variable transmission as described above, there is a prior art described in Japanese Patent Application Laid-Open No. 60-60361, which was proposed by the present applicant. This system uses hydraulic pressure to change the winding radius of a pulley wrapped around a metal V-belt, thereby changing the pulley ratio steplessly.The hydraulic system is equipped with a pressure regulating valve, which adjusts the pulley ratio according to the transmitted torque. Generate line pressure and
It is designed to give optimum tension to the belt. [Problems to be Solved by the Invention] Generally, line pressure decreases as oil temperature increases, but in the past there was no means to correct this, so V-belts decreased as oil temperature increased. There is a problem in that the V-belt loses tension and slips, and as the slip progresses, abnormal wear occurs, reducing the durability of the V-belt. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for detecting the occurrence of slip in order to maintain the durability of a drive belt.

[Means to solve the problem]

For this purpose, the present invention detects the movement of the movable sheave of one or both of the driving pulley and the driven pulley to determine the theoretical pulley ratio, and at the same time calculates the rotational speed of both the driving pulley and the driven pulley. The gist is that the belt slip signal is generated by detecting the actual pulley ratio, and when the absolute value of the deviation between the theoretical pulley ratio and the actual pulley ratio exceeds a predetermined value.

[For production]

By such means, (1) the belt is immediately detected by the slip signal at the iD period when the slip occurs.

【Example】

Hereinafter, one embodiment of the present invention will be specifically described with reference to the drawings. FIG. 2 shows a transmission system of a vehicle incorporating a V-belt continuously variable transmission to which the present invention is applied, where the symbol @1 indicates an electromagnetic powder clutch and 2 indicates a V-belt continuously variable transmission. This V-belt type continuously variable transmission 2 has a forward/reverse switching section 3. Pulley ratio converter 4. It is composed of a final reduction section 5 and a hydraulic control section 6. In the electromagnetic powder clutch 1, a drive member 9 having a built-in coil 8 is integrally connected to a crankshaft 7 from the engine, and a driven member 11 is integrally connected in the rotation direction by a spline to a transmission input shaft 10. These drives and driven members 9°11 are loosely fitted through a gap 12, and the powder chamber 13 to 1! It is designed to collect magnetic particles. In addition, drive member 9
A slip ring 15 is installed through a holder 14, and a power feeding brush 1G is in sliding contact with the slip ring 15 to cause a clutch current to flow through the coil 8. In this way, when a clutch current is applied to the coil 8, m magnetic particles are combined and accumulated in the gap 12 between the drive and driven members 9 and 11 in a chain form due to the lines of magnetic force generated between the drive and driven members 9 and 11. On the other hand, since the driven member 11 does not slip, it becomes integrally connected. On the other hand, clutch r! When the i flow is cut, the coupling force between the drive and the driven member 9.11 due to the electromagnetic powder disappears, resulting in a clutch disengaged state. In this case, if the clutch current is supplied and cut in conjunction with the operation of the switching section 3 of the continuously variable transmission 2 using a shift lever, etc., it is possible to switch from P (parking) or N to neutral) range. When switching to the D (drive), L (low) or R (reverse) range, clutch 1 is automatically connected and disconnected, making it unnecessary to operate the clutch pedal. Next, in the V-belt continuously variable transmission 2, the forward/reverse switching section 3 is connected between the input shaft 10 from the clutch 1 and the main shaft 11 of the V-belt continuously variable transmission 2, which is disposed coaxially therewith. A reverse drive gear 18 integrally connected to the input shaft 10 and a reverse driven gear 19 rotatably engaged with the main shaft 17 are meshed together via a counter gear 20 and an idler gear 21. A switching clutch 22 is provided between the main shaft 17 and the gears 18,19. When the switching clutch 22 is engaged to the gear 18 side from the neutral position of the P or N range, the main shaft 17 is directly connected to the input shaft 10, resulting in a cruising state of the D or L range, and the switching clutch 22 is engaged to the Fi719 side. When the input shaft 1
The power of 0 is decelerated and reversed by the gears 18 to 21 and transmitted to the main shaft 17, resulting in a reverse traveling state in the R range. In the pulley ratio conversion unit 4, a sub-shaft 23 is arranged parallel to the main shaft 17, and a primary pulley 24. A secondary pulley 25 is provided as a driven pulley, and an endless metal V-belt 26 is provided between both pulleys 24 and 25. Each of the pulleys 24 and 25 is divided into two parts, and hydraulic servo devices 27 and 28 are attached to the movable sheaves 24a and 25a to make the pulley interval variable. In this case, the primary pulley 24 moves the movable sheave 24a closer to the fixed sheave 24b to gradually narrow the pulley interval, and conversely, the secondary pulley 25 moves the movable sheave 25a away from the fixed sheave 25b to gradually widen the pulley interval. As a result, the V-belt 26 is wound around the pulleys 24 and 25 so that the ratio of the diameters is changed to output continuously variable power to the DI shaft 23. In the final reduction section 5, a large-diameter final gear 32 meshes with an output gear 31 of an output shaft 30 connected to the subshaft 23 via an intermediate reduction gear 29, and a large-diameter final gear 32 meshes with an output gear 31 of an output shaft 30 connected to the subshaft 23 via an intermediate reduction gear 29. The power is transmitted to the axles 34 and 35 of the left and right drive wheels. Further, the hydraulic control unit 6 has a hydraulic pressure on the primary pulley 24 side so that a pump drive shaft 36 that passes through the main pulley 24 and the inside of the input shaft 10 and is directly connected to the engine crankshaft 7 generates hydraulic pressure during engine operation. A pump 37 is provided. Then, this pump oil pressure is changed to υJtll by the speed change υ1@ device 38 according to the throttle opening degree and engine rotation speed according to the depression of the accelerator, and is transmitted to each hydraulic servo device ff127 on the primary pulley and secondary pulley side via the oil passage 39.40. 28, and is configured to perform continuously variable speed control of the pulley ratio conversion section 4. In FIG. 1, the transmission control device 38 will be explained as follows.
In the hydraulic servo device 27 of the primary pulley 24@, a movable seam 724a is fitted to the cylinder 27a and also serves as a piston, and is operated by the line pressure of the servo chamber 27b, and is also movable in the hydraulic servo device 28 of the secondary pulley 25 side. The sheave 25a is fitted into the cylinder 28a and is operated by the line pressure of the servo chamber 28b. In this case, the movable sheave 24a has a larger line pressure receiving area than the movable sheave 25a. The oil path 40 from the servo '528b of the secondary pulley 25 is
Hydraulic pump 37. An oil passage 3 communicates with an oil reservoir 42 via a filter 41, branches from the hydraulic pump discharge side of this oil passage 40, and communicates with the servo chamber 27b of the primary pulley 24.
9 is provided with a pressure Sl regulating valve 43 and a speed change control valve 44. The speed change control valve 44 has a valve body 45. Spool 46. It consists of a spring 47 which is biased towards one side of the spool 46 and an actuation member 48 which changes the spring force.
A pitot pressure corresponding to the engine rotation speed from a rotation sensor 49 provided on the primary pulley 24 side is guided via an oil passage 50 to a boat 45a that communicates with a pitot pressure q 45e on the opposite side to the spring 47 of the actuating member 48. A throttle cam 51 that rotates according to the throttle opening is in contact with the throttle cam 51 . In addition, the boat 45b of the valve body 45 is connected to the spool 4.
Depending on the position of lands 46a and 46b of 6, they are selectively connected to either a line pressure supply boat 45c or a drain boat 45d, and the boat 45b is connected to the servo 127b through the oil passage 39a of the oil passage 39. , the boat 45c communicates with the pressure regulating valve 43 side through the oil passage 39b, and the drain boat 45d communicates with the oil sump 42 through the drain oil passage 52.
Connects to the side. As a result, in the spool 46 of the speed change control valve 44, the pitot pressure of the pitot pressure changer 45e that corresponds to the engine rotation speed and the force of the spring 47 that corresponds to the throttle opening accompanying the rotation of the throttle cam 51 oppose each other. It operates based on the relationship between these two. That is, when the pitot pressure increases as the engine speed increases, the spool 46 moves to the left in the figure, thereby communicating the boats 45b and 45c, supplying line pressure to the servo v27b of the primary pulley 24, and shifting. Starts shifting to the higher gear side where the ratio becomes smaller. At this time, when the force of the spring 47 corresponding to the throttle opening is large (1), the start point of the shift to the high gear side is delayed. Next, the pressure regulating valve 43 is connected to the valve body 53. Spool 54
, a spring 55 biased to one side of the spool 54, and the boats 53a and 53b on the opposite side of the spool 54 to the spring 55 have pitot pressure of the oil passage 50, respectively. The line pressure of the oil passage 39c is guided. Also spring 55
includes a feedback sensor 5 that engages with the movable sheave 24a of the primary pulley 24 to detect the actual pulley ratio.
6 are connected to increase the spring force as the pulley ratio increases. Furthermore, the pump side oil passage 39C is connected to the spool 54.
The oil passage 39b of the speed change i control valve 44 is always
is connected to. The spool 54 is connected to the boat 53a.
It is balanced by the pitot pressure extending to 100 mm and the force of the spring 55, and by controlling the communication between the line pressure boat 53G and the boat 53d on the drain oil path 52 side by moving the land 54a of the spool 54, the exhaust pressure II till It is supposed to be done. Incidentally, reference numeral 56 indicates a pole check valve provided in the drain oil passage 52 to prevent sudden exhaust pressure action. According to the present invention, the rotary pickup 60 is provided close to the outer periphery of the fixed sheave 24b of the primary pulley 24, and similarly
A rotation pickup 61 is provided close to the outer periphery and detects the rotation speed of the primary pulley 24 and the secondary pulley 25. Further, a potentiometer 62 is provided in contact with the outer surface of the movable sheave 24a of the primary pulley 24 to detect the amount of movement of the movable sheave 24a. FIG. 3 shows a block diagram of the belt slip detection device,
Based on the output signals from the two rotary pickups 60 and 61, the rotational speed N1. The actual pulley ratio 1 is input by inputting the signals from the rotation speed stop sections 63 and 64 that calculate Nt.
It has a pulley ratio calculation section 65 that calculates l-Nt/Nt, and a theoretical pulley ratio calculation section 66 that receives the output signal from the potentiometer 62 and calculates the theoretical pulley ratio iz based on a built-in data table. And the pulley ratio calculation unit 65 and gJ! ! Input the pulley ratio signals it, i from the calculation unit 6G and calculate the absolute deviation rti1i1! A slip determining section 67 is provided which issues a slip signal when zl exceeds a predetermined value of 1fl8. In the V-belt type continuously variable transmission having such a configuration, when the speed change control valve 44 switches to supply line pressure to the servo chamber 27b of the primary pulley 24, the movable sheave 24a of the primary pulley 24 moves toward the fixed sheave 24b. By increasing the belt winding radius, the pulley ratio (speed ratio)
Shifting to a high speed gear with a small value is performed steplessly. Conversely, when the speed change control valve 44 drains the line pressure of the servo v27b of the primary pulley 24, the belt winding radius of the primary pulley 24 decreases and the gear ratio is shifted to a lower gear with a larger pulley ratio (speed ratio). Regarding the line pressure, when the pulley ratio is large, for example when starting a heavy vehicle, the spring 55 of the pressure regulating valve 43 responds to the action of the spring force applied by the feedback sensor 56. and the pitot pressure is low,
Spool 54 does not drain, so line pressure is maintained at a roaring level. As the shift to high gear progresses,
Since the spring force applied by the feedback sensor 56 to the spring 55 decreases and the pitot pressure increases, the spool 54 drains oil and the line pressure gradually decreases. That is, the line pressure is, in principle, controlled so that the V-belt 26 can transmit the required limit of torque within a range that does not cause slip. By the way, the line pressure has a tendency to decrease as the oil temperature rises, so when the oil temperature reaches the upper limit, the V-belt 26
The adjustment force may be insufficient and slip may occur. In this case, in the present invention, the slip of the V-belt 26 is immediately detected by the belt slip detection device. In other words, when the V-belt 26 slips, power transmission from the primary pulley 24 to the secondary pulley 25 becomes insufficient, and the rotation speed Nz of the secondary pulley 25 decreases from the normal rotation speed. Therefore, the actual pulley ratio i 1-N 1/N z calculated by the pulley ratio calculation section 65 is larger than the pulley ratio iz calculated by the theoretical pulley conversion section mouth section 66 . Therefore, a deviation occurs between the two values, and when this exceeds a predetermined value e, a slip signal is issued from the slip determination section 67 and the V
Slip generation of the belt 26 is quickly detected at an early stage. This allows you to lower the clutch transmission torque, tighten the throttle a little, increase line pressure, etc.
Some means can be provided to eliminate the slippage of the V-belt 26, and the inconvenience of causing abnormal wear of the V-belt 26 and reducing its durability can be eliminated. FIG. 4 shows another embodiment of the invention. In this embodiment, only the signal path from the potentiometer to the theoretical pulley ratio calculating section differs from the previous embodiment, so the same parts will be designated by the same reference numerals as in FIG. 3, and a description thereof will be omitted. In this embodiment, in addition to the potentiometer 62, another potentiometer 68 is provided. Although this is not shown in FIG. 1, the movable sheave 25a of the secondary pulley 25
The amount of movement of the movable sheave 25a is detected by contacting the outer surface of the movable sheave 25a. and two potentiometers 6
2. Input the output signal from 68 and use the built-in data table to determine the hanging radius of the V-belt 26 of the primary pulley 24 and secondary pulley 2j)! Pulley radius calculation units 69 and 70 are provided to calculate +'2, respectively. Furthermore, by inputting the signals from these, the theoretical pulley ratio fs-
A theoretical pulley ratio calculation unit 71 for calculating rt/rt is provided, and the pulley ratio signal i3 from this is inputted to the slip determination unit 67 as in the previous embodiment, and the pulley ratio signals 11 and 1
3 is configured to issue a slip signal when the absolute value of the deviation exceeds a predetermined value of 0. In this embodiment, since the theoretical pulley ratio calculation unit 71 uses the belt winding radii rl and r of the primary pulley 24 and secondary pulley 25 as input data, the theoretical pulley ratio will be deviated even when the load fluctuates, resulting in belt slip. The detection accuracy can be significantly improved.

【Effect of the invention】

As explained above, according to the present invention, when a slip occurs in the V-belt, it is immediately detected as a slip signal, so that the durability of the V-belt can be maintained by preventing the progression of the slip.

[Brief explanation of drawings]

Fig. 1 is a hydraulic system diagram of a V-belt continuously variable transmission showing an embodiment of the present invention, and Fig. 2 is a skeleton of a vehicle transmission system incorporating the V-belt continuously variable transmission to which the present invention is applied. 3 is a block diagram of a belt slip detection device according to one embodiment, and FIG. 4 is a block diagram of a belt slip detection device according to another embodiment. DESCRIPTION OF SYMBOLS 1... Electromagnetic powder type clutch, 2... V-belt type continuously variable transmission, 3... Forward/forward switching section, 4... Pulley ratio conversion section, 5... Final reduction section, 6...・Hydraulic control unit, 24...
Primary pulley, 24a... Movable sheave, 25...
・Secondary pulley, 25a...Movable sheave, 2G・
... V-belt, 43... Pressure adjustment valve, 44... Speed change control valve, 60.61... Rotation pickup, 62.6
8... Potentiometer, 63.64... Rotation speed calculation section, 65... Pulley ratio calculation section, 66... Theoretical pulley ratio calculation section, 67... Slip determination section, 69.70.
... Pulley radius calculation section, 11... Theoretical pulley ratio calculation section.

Claims (1)

[Claims] The theoretical pulley ratio is determined by detecting the amount of movement of the movable sheave of one or both of the driving pulley and the driven pulley, and at the same time, the actual pulley ratio is determined by detecting the rotation speed of both the driving pulley and the driven pulley. A belt slip detection method for a V-belt continuously variable transmission, characterized in that a V-belt slip signal is generated when the absolute value of the deviation between the calculated theoretical pulley ratio and the actual pulley ratio exceeds a predetermined value. .