JP2004092539A - Belt slippage prevention system for belt-type continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an occurrence of a belt of a CVT unit from slipping even when a vehicle travels in the opposite direction from the traveling direction selected by a shift lever. <P>SOLUTION: The system is equipped with: a primary pulley 41 on the input side and a secondary pulley 42 on the output side whose groove widths change according to oil pressure; a belt-type continuously variable transmission 40 equipped with a belt 43 for being wound around both of the pulleys 41, 42, and whose pulley contact radius changes according to the groove widths; the shift lever 56 for indicating the traveling direction of the vehicle; a pulley reverse rotation determining means 61a for determining whether the secondary pulley 42 is rotating in reverse to the traveling direction selected by the shift lever 56; and an engine output restriction means 62 for preventing the belt 43 from slipping by restricting the output of the engine when the pulley reverse rotation determining means 61a determines the secondary pulley 42 to be rotating in reverse. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt slip prevention system for a belt-type continuously variable transmission that is suitably used for a power transmission system that transmits a driving force of an engine of an automobile or the like to driving wheels.
[0002]
[Prior art]
2. Description of the Related Art As a transmission mounted on an automobile or the like, for example, a belt-type CVT (Continuously Variable Transmission) is conventionally known. The belt-type CVT includes a primary pulley for inputting the driving force of the engine, a secondary pulley for outputting the driving force to the driving wheels, a primary pulley and a secondary pulley. And a V-belt for transmission to the vehicle. Pulley groove widths of the primary pulley and the secondary pulley are variable by hydraulic pressure. At the time of shifting, by supplying or discharging hydraulic pressure to the primary pulley and the secondary pulley, the pulley groove width is adjusted, and the ratio (pulley ratio) of the contact radius (effective radius) of the V belt to the primary pulley and the secondary pulley is changed. The ratio of the number of revolutions between the input and output (speed change ratio) is adjusted.
[0003]
[Problems to be solved by the invention]
In such a belt type CVT, it is important not to cause belt slippage in order to prevent a decrease in the durability of the belt.
[0004]
In such a belt type CVT, the inventor of the present invention proposes that when the vehicle travels in the direction opposite to the traveling direction selected by the shift lever (for example, while the shift lever is in the D (forward) range on an uphill, When the vehicle moves backward without stepping on the pedal or the brake pedal, etc.), the hydraulic pressure balance between the primary pressure and the secondary pressure is lost, and as a result, the primary pressure decreases and the torque capacity (CVT is transmitted without slipping the belt) (Maximum possible torque) has been found to reduce belt slippage. The present invention has been made in view of such problems, and an object of the present invention is to provide a belt slip prevention system for a belt-type continuously variable transmission that does not cause the belt slip of the CVT unit even in the above-described situation. The purpose is.
[0005]
[Means for Solving the Problems]
The present invention solves the above problem by the following means. Note that, for easy understanding, reference numerals corresponding to the embodiments of the present invention are given, but the present invention is not limited thereto.
[0006]
In the first invention, the primary pulley (41) on the input side and the secondary pulley (42) on the output side, the groove width of which changes according to the oil pressure, are wound around the primary pulley and the secondary pulley, and A belt-type continuously variable transmission (40) having a belt (43) whose pulley contact radius changes in response thereto, a shift lever (56) for indicating a traveling direction of the vehicle, and a forward range or a reverse range by the shift lever. Is selected, the pulley reverse rotation determining means (61a) for determining whether the secondary pulley is reversely rotating in the direction opposite to the traveling direction selected by the shift lever, and the pulley When the reverse rotation determining means determines reverse rotation of the secondary pulley, an engine output limiter that limits engine output to prevent belt slippage. Characterized in that it comprises a (62).
[0007]
In a second aspect based on the first aspect, the engine output limiting means (62) controls the torque input to the belt-type continuously variable transmission to be equal to or less than a torque capacity calculated from a gear ratio and a hydraulic pressure. The engine output is limited.
[0008]
According to a third aspect of the present invention, the primary pulley (41) on the input side and the secondary pulley (42) on the output side, the groove width of which changes according to the oil pressure, and the primary pulley and the secondary pulley are wound around the primary pulley and the secondary pulley. A belt-type continuously variable transmission (40) having a belt (43) whose pulley contact radius changes in response thereto, a shift lever (56) for indicating a traveling direction of the vehicle, and a forward range or a reverse range by the shift lever. Is selected, the pulley reverse rotation determining means (61a) for determining whether the secondary pulley is reversely rotating in the direction opposite to the traveling direction selected by the shift lever, and the pulley When reverse rotation of the secondary pulley is determined by the reverse rotation determining means, the hydraulic pressure supplied to the primary pulley is increased to prevent belt slippage. Characterized in that it comprises a hydraulic control unit (61b).
[0009]
In a fourth aspect based on any one of the first to third aspects, the pulley reverse rotation determining means (61a) comprises: a secondary pulley rotation speed sensor (52) for detecting a rotation speed of the secondary pulley; An accelerator opening sensor (57) for detecting an opening, a brake sensor (55) for detecting ON / OFF of a brake, a primary pressure sensor (53) for detecting a primary pressure, and detecting a secondary pressure. A secondary pressure sensor (54), a range change by the shift lever (56), a vehicle speed is calculated from a rotation speed of the secondary pulley, and the vehicle speed is equal to or lower than a predetermined value, and the accelerator opening sensor is When the brake sensor detects that the accelerator is fully closed and the brake sensor detects that the brake is on and then detects that the brake is off, Dali pressure despite maintaining a predetermined value or more, when the primary pressure falls below a predetermined value, and judging the reverse rotation of the secondary pulley is generated.
[0010]
[Action / Effect]
According to the first aspect, the output of the engine is limited when the secondary pulley is rotating in the opposite direction to the traveling direction selected by the shift lever, so that belt slippage can be prevented. Thus, the service life of the belt can be extended.
[0011]
According to the second aspect, the engine output is limited so that the torque input to the belt-type continuously variable transmission is equal to or less than the torque capacity calculated from the gear ratio and the hydraulic pressure. Therefore, the engine output is excessively limited. Nothing.
[0012]
According to the third aspect, when the secondary pulley is rotating in the opposite direction to the traveling direction selected by the shift lever, the hydraulic pressure supplied to the primary pulley is increased, so that the belt is more securely. Slip can be prevented.
[0013]
According to the fourth aspect, the reverse rotation of the pulley is determined based on whether or not the balance between the primary pressure and the secondary pressure has been lost. Therefore, it is not necessary to provide a dedicated sensor for determining the reverse rotation.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings and the like.
[0015]
FIG. 1 is a schematic configuration diagram showing an embodiment of a belt slip prevention system for a belt-type continuously variable transmission according to the present invention.
[0016]
The belt-type continuously variable transmission 1 includes a hydraulic pump 10, a torque converter (hereinafter, abbreviated as "torque converter") 20, a forward / backward switching unit 30, and a CVT transmission unit 40, and is controlled by the control unit 60. You. The belt-type continuously variable transmission 1 receives a driving force from the engine 70, changes the driving force, and outputs the speed to the driving wheels 80.
[0017]
The hydraulic pump 10 is driven by the engine 70 to pump oil. The pressure-fed oil is pressure-adjusted and sent to the forward / backward switching unit 30 and the CVT transmission unit 40, and is used for forward / backward switching and gear shifting.
[0018]
The torque converter 20 is provided between the engine 70 and the forward / backward switching unit 30, and transmits the driving force of the engine 70 by the flow of oil inside. Further, torque converter 20 has a lock-up mechanism for eliminating a rotation difference between the pump impeller and the turbine liner.
[0019]
The forward / backward switching unit 30 includes a planetary gear 31 that switches a power transmission path between the engine side and the CVT transmission unit side, a forward clutch plate 32, and a reverse clutch plate 33. The forward clutch plate 32 is connected to the forward clutch piston, and is fastened to the planetary gear 31 by the hydraulic pressure (forward clutch pressure) supplied to the forward clutch piston chamber 32a when the vehicle advances. The reverse clutch plate 33 is connected to the reverse clutch piston, and is fastened to the planetary gear 31 by the force of the hydraulic pressure (reverse clutch pressure) supplied to the reverse clutch piston chamber 33a when the vehicle reverses. Further, in the neutral position (neutral or parking), no hydraulic pressure is supplied, and both the forward clutch plate 32 and the reverse clutch plate 33 are released. When the forward clutch plate 32 is fastened to the planetary gear 31, forward rotation is output, and when the reverse clutch plate 33 is fastened to the planetary gear 31, reverse rotation is output.
[0020]
The forward clutch plate 32 and the reverse clutch plate 33 are exclusively engaged. When the vehicle is moving forward (range signal = D range), the forward clutch pressure is supplied to fasten the forward clutch plate 32 and the reverse clutch pressure is drained. And the reverse clutch plate 33 is released. On the other hand, when reversing (range signal = R range), the forward clutch pressure is connected to the drain, the forward clutch plate 32 is released, the reverse clutch pressure is supplied, and the reverse clutch plate 33 is engaged. At the neutral position (range signal = N range), the forward clutch pressure and the reverse clutch pressure are connected to the drain, and both the forward clutch plate 32 and the reverse clutch plate 33 are released.
[0021]
The CVT transmission unit 40 includes a primary pulley 41, a secondary pulley 42, and a V-belt 43.
[0022]
The primary pulley 41 is a pulley on the input shaft side for inputting the driving force of the engine 70. The primary pulley 41 has a fixed conical plate 41a that rotates integrally with the input shaft 41c, a V-shaped pulley groove disposed opposite to the fixed conical plate 41a, and a hydraulic pressure acting on the primary pulley (hereinafter, referred to as the primary pulley 41). And a movable conical plate 41b that can be displaced in the axial direction by “primary pressure”. This primary pressure is supplied to the movable conical plate 41b after the pressure of the oil pumped by the hydraulic pump 10 is adjusted by the primary pressure adjusting device 44. The primary pressure is measured by a primary pressure sensor 53 provided in the middle of a supply path from the primary pressure adjusting device 44 to the movable conical plate 41b. The rotation speed (input rotation) of the primary pulley 41 is detected by a primary pulley rotation speed sensor 51.
[0023]
Secondary pulley 42 transmits the driving force transmitted by V-belt 43 to driving wheels 80 via idler gears and differential gears. The secondary pulley 42 has a fixed conical plate 42a that rotates integrally with the output shaft 42c, a V-shaped pulley groove disposed opposite to the fixed conical plate 42a, and a hydraulic pressure acting on the secondary pulley (hereinafter, referred to as a secondary pulley 42). A movable conical plate 42b that can be displaced in the axial direction according to “secondary pressure”). The secondary pressure is adjusted by an oil pressure pumped by the hydraulic pump 10 by a secondary pressure adjusting device 45 and supplied to the movable conical plate 42b. The secondary pressure is measured by a secondary pressure sensor 54 provided in the supply path from the secondary pressure adjusting device 45 to the movable conical plate 42b. The pressure receiving area of the secondary pulley and the pressure receiving area of the primary pulley are equal or almost equal. The rotation (output rotation) speed of the secondary pulley 42 is detected by a secondary pulley rotation speed sensor 52. The vehicle speed can be calculated from the rotation speed of the secondary pulley 42.
[0024]
V-belt 43 is wound around primary pulley 41 and secondary pulley 42, and transmits the driving force input to primary pulley 41 to secondary pulley 42.
[0025]
When the gear ratio is large (low), the primary pulley 41 increases the groove width to reduce the contact radius of the V-belt 43, and the secondary 42 narrows the groove width to increase the contact radius of the V-belt 43. When the speed change ratio is low (Hi side), the primary pulley 41 narrows the groove width to increase the contact radius of the V-belt 43, and the secondary 42 widens the groove width to decrease the contact radius of the V-belt 43.
[0026]
The control unit 60 is connected with a brake sensor 55 for detecting ON / OFF of a brake, a shift lever 56 for instructing a traveling direction (forward / backward), and an accelerator opening sensor 57 for detecting an accelerator opening. ing.
[0027]
FIG. 2 is a block diagram showing the configuration of the control unit in the belt slip prevention system of the belt-type continuously variable transmission according to the present invention.
[0028]
When the secondary pulley rotates in the direction opposite to the select direction of the shift lever, the torque capacity decreases. Therefore, according to the present invention, when the control unit 60 detects such a state, the output of the engine is suppressed and the primary pulley is controlled. To prevent the belt-type continuously variable transmission from slipping by increasing the hydraulic pressure supplied to the belt and increasing the force with which the primary pulley clamps the belt.
[0029]
Hereinafter, the control unit 60, which is particularly important in the present invention, will be described in detail.
[0030]
The control unit 60 has an ATCU 61 and an ECM 62.
[0031]
The ATCU 61 includes a pulley reverse rotation determination unit 61a, a hydraulic control unit 61b, a torque limit start / end condition determination unit 61c, a torque capacity calculation unit 61d, an input torque calculation unit 61e, a torque limit determination unit 61f, It includes a limit value calculation unit 61g and a torque limit value output unit 61h.
[0032]
The pulley reverse rotation determination unit 61a inputs a range signal from the inhibitor switch of the shift lever 56. Further, the pulley reverse rotation determination unit 61a receives a secondary pulley rotation signal (output rotation signal) from the secondary pulley rotation speed sensor 52. Further, the pulley reverse rotation determination unit 61a inputs the primary actual oil pressure and the secondary actual oil pressure from the primary pressure sensor 53 and the secondary pressure sensor 54. Then, the range signal did not change, the vehicle speed calculated from the output rotation signal was equal to or lower than the set value (for example, 3 km / h), and the brake signal was changed from ON to OFF in an idle state where the accelerator opening was fully closed. If the primary pressure falls below the set value, even though the secondary pressure does not decrease within the set time later, the balance between the primary pressure and the secondary pressure has been lost. It can be determined that reverse rotation has occurred. In this case, since the case where the D range is selected is assumed, the vehicle is moving backward. For example, when the vehicle is placed on a downhill with the R range selected. In this case, the reverse rotation of the pulley also occurs.
[0033]
When the pulley reverse rotation determining unit 61a determines that the pulley rotates in the reverse direction, the hydraulic control unit 61b operates the hydraulic pump 10 to increase the line pressure to the maximum pressure that can be generated. This prevents the primary pressure from lowering. It is rare that the pulley rotates in the direction opposite to the select direction of the shift lever. Therefore, such control is rarely required. Therefore, in the present embodiment, in consideration of this point, the line pressure is increased to the maximum pressure that can be generated in the case described above. However, the line pressure may be appropriately controlled to an optimum pressure, and in such a case, the output of the pump can be suppressed as much as possible in normal times.
[0034]
The torque limit start / end condition determining unit 61c determines a condition for starting or ending the torque limit. Specifically, when the pulley reverse rotation determination unit 61a determines that the pulley rotates in the reverse direction, torque restriction is started, and the flag is set to 1 at that time. When the vehicle speed becomes equal to or higher than a set value (for example, 10 km / h), the torque limitation is ended, and in that case, the flag is set to 0.
[0035]
The torque capacity calculation unit 61d outputs a primary pulley rotation signal (input rotation signal), a secondary pulley rotation signal (output rotation signal) from the primary pulley rotation speed sensor 51, the secondary pulley rotation speed sensor 52, the primary pressure sensor 53, and the secondary pressure sensor 54. ), Input the actual oil pressure signal. Then, the torque capacity calculation unit 61d calculates the speed ratio from the input rotation signal and the output rotation signal, and calculates the torque capacity based on the relationship between the speed ratio and the actual oil pressure.
[0036]
The input torque calculation unit 61e inputs the engine torque from the ECM 62 and uses the engine torque as the input torque.
[0037]
The torque limit determining unit 61f compares the torque capacity calculated by the torque capacity calculating unit 61d with the input torque calculated by the input torque calculating unit 61e to determine whether it is necessary to limit the input torque. That is, when the input torque exceeds the torque capacity, it is necessary to limit the input torque (hatched portion in the figure), and it is determined that it is not necessary to limit the input torque unless the input torque exceeds the torque capacity.
[0038]
The torque limit value calculation unit 61g calculates a torque limit value when the input torque needs to be limited. Specifically, the torque capacity is set to a torque limit value.
[0039]
The torque limit value output unit 61h outputs the torque limit value as a request value to the torque down amount calculation unit 62b based on the flag of the torque limit start / end condition determination unit 61c. Specifically, when the flag is 1, a signal (that is, torque capacity) of the torque limit value calculation unit 61g is output as a torque limit value. When the flag is 0, it is not necessary to limit the torque. In this case, the limit request value is output as the Max value. The reason for this is that the torque reduction on the engine side is performed when “engine torque> restricted request value”.
[0040]
The ECM 62 is an engine output control unit that includes an engine torque calculation unit 62a, a torque reduction amount calculation unit 62b, and an electronically controlled throttle (hereinafter abbreviated as “electric slot”) control unit 62c.
[0041]
The engine torque calculation unit 62a receives an engine fuel injection amount signal, an engine rotation signal, and an accelerator opening (TV0) signal, and calculates a torque output from the engine based on these signals. Then, the calculation result of the engine torque is output to the torque reduction amount calculation unit 62b and the input torque calculation unit 61e.
[0042]
The torque down amount calculation unit 62b calculates the torque down amount based on the torque limit value signal input from the torque limit value output unit 61h of the ATCU 61 and the engine torque signal input from the engine torque calculation unit 62a, and outputs the torque down signal. Output to the braking / throttle opening control unit 62c.
[0043]
The electronically controlled throttle opening control unit 62c controls the electronically controlled throttle opening in order to realize the torque reduction amount input from the torque reduction amount calculation unit 62b.
[0044]
FIG. 3 is a flowchart illustrating the processing of the control unit in the belt slip prevention system of the belt-type continuously variable transmission according to the present invention.
[0045]
In step S1, the pulley reverse rotation determination unit 61a determines the reverse rotation of the pulley. If the reverse rotation of the pulley can be determined, the process proceeds to step S2, and if not, the process proceeds to step S9.
[0046]
In step S2, the hydraulic pressure control unit 61b starts hydraulic pressure increase control, and operates the hydraulic pump 10 to increase the line pressure to the maximum pressure that can be generated.
[0047]
In step S3, the torque capacity is calculated from the gear ratio and the actual oil pressure by the torque capacity calculation unit 61d.
[0048]
In step S4, the engine torque is calculated by the engine torque calculator 62a, and the input torque is calculated by the input torque calculator 61e.
[0049]
In step S5, the torque limit determining unit 61f determines whether the input torque is larger than the torque capacity. If the input torque is larger, the process proceeds to step S6, and if not, the process proceeds to step S7.
[0050]
In step S6, the input torque is limited by the torque limit value calculation unit 61g and the torque limit value output unit 61h so as to be equal to or less than the torque capacity, and the torque output amount calculation unit 62b and the electric slot opening control unit 62c determine the engine output. Down.
[0051]
In step S7, the hydraulic pressure increase control of the hydraulic pressure control unit 61b ends.
[0052]
In step S8, the torque limit is ended, and the Max value is output from the torque limit value output unit 61h as the limit request value.
[0053]
In step S9, no torque limitation is performed.
[0054]
The above processing is continuously performed at regular intervals (for example, every 10 msec) during traveling.
[0055]
According to the present embodiment, when the secondary pulley is rotating reversely in the direction opposite to the traveling direction selected by the shift lever, the maximum torque that the CVT can transmit without sliding the belt decreases. However, in this case, since the output of the engine is limited, belt slippage can be prevented, and the life of the belt can be extended.
[0056]
Further, since the torque capacity calculated based on the gear ratio and the actual oil pressure is used as the torque limit request value, and the engine output is controlled based on the torque limit request value, the engine output is not excessively limited, and the appropriate control is performed. Is now possible.
[0057]
Further, when the secondary pulley is rotating in the opposite direction to the traveling direction selected by the shift lever, the hydraulic pressure supplied to the primary pulley is increased, so that belt slippage can be more reliably prevented.
[0058]
Furthermore, since the reverse rotation of the pulley is determined based on whether or not the balance between the primary pressure and the secondary pressure is lost, a sensor for determining the reverse rotation is unnecessary, and the system can be realized at low cost.
[0059]
Without being limited to the embodiments described above, various modifications and changes can be made within the scope of the technical idea, and it is apparent that they are equivalent to the present invention. For example, in the above-described embodiment, the pulley reverse rotation determination unit 61a determines the reverse rotation of the pulley based on whether or not the balance between the primary pressure and the secondary pressure has been lost. May be arranged, and the rotation direction of the pulley may be determined based on which sensor detects the mark first.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an embodiment of a belt slip prevention system for a belt-type continuously variable transmission according to the present invention.
FIG. 2 is a block diagram showing a configuration of a control unit in the belt slip prevention system of the belt-type continuously variable transmission according to the present invention.
FIG. 3 is a flowchart illustrating processing of a control unit in the belt slip prevention system of the belt-type continuously variable transmission according to the present invention.
[Explanation of symbols]
Reference Signs List 1 belt-type continuously variable transmission 10 hydraulic pump 20 torque converter 30 forward / backward switching unit 40 CVT transmission unit 41 primary pulley 42 secondary pulley 43 V-belt 60 control unit 61 ATCU
61a Pulley reverse rotation determination section 61b Hydraulic control section 61c Torque limit start / end condition determination section 61d Torque capacity calculation section 61e Input torque calculation section 61f Torque limit determination section 61g Torque limit value calculation section 61h Torque limit value output section 62 ECM
62a Engine torque calculation unit 62b Torque reduction amount calculation unit 62c Electric throttle (electric slot) opening degree control unit 70 Engine 80 Drive wheels

Claims (4)

An input-side primary pulley and an output-side secondary pulley whose groove width changes in accordance with oil pressure, and a belt wound around the primary pulley and the secondary pulley and whose pulley contact radius changes in accordance with the groove width. Belt type continuously variable transmission,
A shift lever for instructing the traveling direction of the vehicle,
When the forward range or the reverse range is selected by the shift lever, the pulley reverse rotation that determines whether the secondary pulley is reversely rotated in the direction opposite to the traveling direction selected by the shift lever. Determining means;
A belt slip prevention system for a belt-type continuously variable transmission, comprising: engine output limiting means for limiting engine output and preventing belt slip when the pulley reverse rotation determining means determines reverse rotation of the secondary pulley. The engine output limiting means limits the engine output so that the torque input to the belt-type continuously variable transmission is equal to or less than a torque capacity calculated from a gear ratio and a primary actual hydraulic pressure and a secondary actual hydraulic pressure. The belt slip prevention system for a belt-type continuously variable transmission according to claim 1, wherein: An input-side primary pulley and an output-side secondary pulley whose groove width changes in accordance with oil pressure, and a belt wound around the primary pulley and the secondary pulley and whose pulley contact radius changes in accordance with the groove width. Belt type continuously variable transmission,
A shift lever for instructing the traveling direction of the vehicle,
When the forward range or the reverse range is selected by the shift lever, the pulley reverse rotation that determines whether the secondary pulley is reversely rotated in the direction opposite to the traveling direction selected by the shift lever. Determining means;
A hydraulic control means for increasing a hydraulic pressure supplied to the primary pulley to prevent belt slippage when the pulley reverse rotation determining means determines reverse rotation of the secondary pulley; system. The pulley reverse rotation determining means includes:
A secondary pulley rotation speed sensor for detecting a rotation speed of the secondary pulley,
An accelerator opening sensor for detecting the accelerator opening,
A brake sensor for detecting ON / OFF of a brake;
A primary pressure sensor for detecting the primary pressure,
A secondary pressure sensor for detecting secondary pressure,
There is no range change by the shift lever, the vehicle speed is calculated from the rotation speed of the secondary pulley, the vehicle speed is equal to or less than a predetermined value, the accelerator opening sensor detects that the accelerator is fully closed, and the brake sensor is a brake. In a case where the brake OFF is detected after the ON is detected, the reverse rotation of the secondary pulley occurs when the primary pressure falls below the predetermined value, even though the secondary pressure is maintained at or above the predetermined value. The belt slip prevention system for a belt-type continuously variable transmission according to any one of claims 1 to 3, wherein it is determined that the belt slip has occurred.

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