JP4389462B2 - Slip detection device for continuously variable transmission - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for detecting slippage of a continuously variable transmission capable of continuously changing a gear ratio.
[0002]
[Prior art]
Conventionally, as a continuously variable transmission capable of continuously changing the gear ratio, the belt winding radius of the driving pulley and the driven pulley is continuously changed by changing the groove width of the pulley around which the belt is wound. There are known a configuration in which the transmission ratio is changed, and a configuration in which a roller sandwiched between disks on the input side and the output side is tilted to continuously change the gear ratio. In these continuously variable transmissions, torque is transmitted using the frictional force generated between the belt and the pulley and the shearing force of the oil film interposed between the disk and the roller. Limited by force and shear force. Therefore, when a torque greater than the transmission torque capacity acts on the continuously variable transmission, a slip occurs between the belt and the pulley or between the disk and the roller.
[0003]
When excessive slip occurs in a continuously variable transmission, damage such as wear or adhesion may occur on the torque transmission surface of a pulley or a disk. Therefore, in order to avoid this type of inconvenience, it is conceivable to increase the transmission torque capacity by increasing the clamping pressure for clamping the belt or the roller. However, when the clamping pressure is increased, the power transmission efficiency is reduced, and for example, the advantage of using a continuously variable transmission in a vehicle is impaired.
[0004]
Therefore, for example, in the invention described in Patent Document 1, the actual transmission ratio is calculated based on the input rotation speed and the output rotation speed for the belt type continuously variable transmission, and the change rate of the actual transmission ratio is calculated. On the other hand, the theoretical gear change rate is obtained based on the gear ratio, the engine speed, the throttle opening, and the control amount of the gear change control valve, and the actual gear ratio change rate is calculated as the theoretical gear change rate. When it is larger, the occurrence of slip is determined.
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 6-11022 (paragraph (0129), FIGS. 6 to 12)
[0006]
[Problems to be solved by the invention]
In the invention described in Patent Document 1 described above, the slip is determined when the actual gear ratio change rate is larger than the theoretical gear change rate, but there are various modes in which slip occurs in the continuously variable transmission. For example, if the continuously variable transmission slips when accelerating by greatly depressing the accelerator pedal, the rotational speed of the input side member such as the drive pulley increases rapidly, and the gear ratio changes in the downshift direction. Since the ratio increases, the slip can be detected by the invention described in Patent Document 1 described above. However, when slip occurs in the continuously variable transmission during engine braking or regenerative braking in a hybrid vehicle, The number of rotations of the rotating member decreases, the gear ratio changes in the upshift direction, and the change becomes slow. That is, in such slipping at the time of deceleration, the actual gear ratio change rate does not always increase. Therefore, in the invention described in Patent Document 1 described above, slippage of the continuously variable transmission cannot always be detected accurately.
[0007]
In addition, when pressure oil is supplied and discharged so as to achieve the gear ratio based on the gear change command, the supply and discharge amount of pressure oil may vary from the assumed amount, and the delay in response of hydraulic control is a factor. As a result, the flow rate may vary. In addition, pressure oil leakage may occur, so in the end, the flow rate of the pressure oil with respect to the shift command may not be uniquely determined. As a result, due to these error factors, the actual gear ratio change rate and the theoretical If the speed ratio change rate is simply compared, the slip of the continuously variable transmission may not be detected accurately.
[0008]
This invention was made paying attention to said technical subject, and it aims at providing the control apparatus which can detect the slip of a continuously variable transmission correctly based on a measured value and a theoretical value. To do.
[0009]
[Means for Solving the Problem and Action]
To achieve the above object, a first aspect of the invention, to enable you changing the speed change ratio steplessly by changing the winding radius of the belt in accordance with the inflow out of the pressure oil with respect to the sheave In the belt type continuously variable transmission slip detection device, the change to the sheave calculated based on the actual transmission ratio change rate obtained as the amount of change per unit time of the ratio between the input side rotation speed and the output side rotation and the shift command. Absolute value calculation means for obtaining the absolute value of the difference from the theoretical gear ratio change rate obtained from the inflow / outflow amount of pressure oil per unit time , the absolute value obtained by the absolute value calculation means and a predetermined threshold value And a slip determination unit including slip determination based on a comparison result with the slip detection device for a continuously variable transmission.
[0010]
Therefore, according to the first aspect of the present invention, an actual measurement value and a theoretical value are obtained for a gear ratio such as a gear ratio and a gear ratio change rate, and a value based on a comparison of a difference or a ratio between the actual measurement value and the theoretical value. The absolute value of is obtained. Then, slipping Rino occurred is determined by such a comparison result between a predetermined threshold value based on the absolute value. For this reason , slip is determined based not only on the magnitude of each absolute value, but also on a threshold value that can reflect the operating state of the vehicle. Therefore, slip that increases the rotational speed on the input side of the continuously variable transmission. In addition, slipping or the like in which the rotational speed on the input side decreases is accurately detected.
[0011]
Further, the invention of claim 2, in the invention of claim 1, wherein the slippage determining means, slide down the CVT you comprising the aforementioned means to vary based on the threshold to the speed ratio It is a detection device.
[0012]
Therefore, in the invention of claim 2, the absolute value of the difference between the actual gear ratio change rate and the theoretical gear ratio change rate is compared with a predetermined threshold value, and slip is determined, and the threshold value is set to the gear shift rate. Different values are set based on the ratio. For example, the smaller the gear ratio, the smaller the threshold value. As a result, it is possible to determine the slip according to the actual slip rotation speed. In other words, a slip with a certain influence or more on damage or durability is accurately detected regardless of the speed ratio.
[0013]
The invention according to claim 3 is the invention according to claim 1 or 2, wherein the continuously variable transmission is configured such that a transmission torque capacity changes according to a clamping pressure, and slip is determined by the slip determination means. In this case, the slip detection device is provided with a slip countermeasure control means for increasing the pinching pressure when it is applied.
[0014]
Therefore, in the invention of claim 3, when the occurrence of slip is determined, the clamping pressure is increased and the transmission torque capacity of the continuously variable transmission is increased. That is, since slipping occurred due to the relatively low clamping pressure, the slipping is prevented or suppressed by increasing the clamping pressure.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Next, the present invention will be described based on specific examples. First, the vehicle drive system and its control system targeted by the present invention will be described. FIG. 3 schematically shows a drive system including the belt type continuously variable transmission 1 as a transmission. The machine 1 is connected to a power source 3 through a forward / reverse switching mechanism 2.
[0016]
The power source 3 is constituted by an internal combustion engine, or an internal combustion engine and an electric motor, or an electric motor, and is mainly a drive member that generates power for traveling. In the following description, the power source 3 is referred to as the engine 3. The forward / reverse switching mechanism 2 is a mechanism that is employed when the rotational direction of the engine 3 is limited to one direction, and outputs the input torque as it is, or reversely outputs it. It is configured as follows.
[0017]
In the example shown in FIG. 3, a double pinion type planetary gear mechanism is employed as the forward / reverse switching mechanism 2. That is, the ring gear 5 is arranged concentrically with the sun gear 4, and the pinion gear 6 meshed with the sun gear 4 and the pinion gear 6 and the other pinion gear 7 meshed with the ring gear 5 are arranged between the sun gear 4 and the ring gear 5. The pinion gears 6 and 7 are held by the carrier 8 so as to rotate and revolve freely. A forward clutch 9 for integrally connecting the two rotating elements (specifically, the sun gear 4 and the carrier 8) is provided, and the direction of the torque to be output by selectively fixing the ring gear 5 is provided. A reverse brake 10 for reversing is provided.
[0018]
The continuously variable transmission 1 has the same configuration as a conventionally known belt-type continuously variable transmission, and each of a driving pulley 11 and a driven pulley 12 arranged in parallel to each other includes a fixed sheave, a hydraulic type The movable sheave is moved back and forth in the axial direction by the actuators 13 and 14. Accordingly, the groove width of each pulley 11 and 12 is changed by moving the movable sheave in the axial direction, and accordingly, the winding radius of the belt 15 wound around each pulley 11 and 12 (the effective diameter of the pulleys 11 and 12). ) Changes continuously, and the gear ratio changes steplessly. The drive pulley 11 is connected to a carrier 8 that is an output element in the forward / reverse switching mechanism 2.
[0019]
The actuator 14 in the driven pulley 12 is supplied with hydraulic pressure (line pressure or its correction pressure) according to the torque input to the continuously variable transmission 1 via a hydraulic pump, a hydraulic control device, etc. (not shown). Yes. Therefore, in this embodiment, each sheave in the driven pulley 12 pinches the belt 15, whereby tension is applied to the belt 15, and clamping pressure (contact pressure) between the pulleys 11, 12 and the belt 15 is ensured. It is like that. On the other hand, the hydraulic oil corresponding to the speed ratio to be set is supplied to the actuator 13 in the drive pulley 11, and the groove width (effective diameter) corresponding to the target speed ratio is set. The supply and discharge of the pressure oil is controlled by controlling a flow rate control valve (not shown) connected to the actuator 13.
[0020]
The driven pulley 12 is connected to a differential 17 through a gear pair 16, and torque is output from the differential 17 to a drive wheel 18.
[0021]
Various sensors are provided in order to detect the operation state (running state) of the vehicle on which the continuously variable transmission 1 and the engine 3 are mounted. That is, an engine speed sensor 19 that detects the speed of the engine 3 and outputs a signal, an input speed sensor 20 that detects the speed of the drive pulley 11 and outputs a signal, and the speed of the driven pulley 12 are detected. An output rotation speed sensor 21 for outputting a signal is provided. Although not specifically shown, an accelerator opening sensor that detects a depression amount of the accelerator pedal and outputs a signal, a throttle opening sensor that detects a throttle valve opening and outputs a signal, and a brake pedal are depressed. A brake sensor or the like that outputs a signal in case is provided. In addition, a hydraulic sensor 24 for detecting the pressure of the hydraulic actuator 14 on the driven pulley 12 side for setting the belt clamping pressure is provided.
[0022]
In order to control the engagement / release of the forward clutch 9 and the reverse brake 10, the control of the clamping force of the belt 15, and the control of the gear ratio, an electronic control unit for transmission (CVT-ECU) 22 is provided. The electronic control unit 22 is configured mainly by a microcomputer as an example, performs calculations according to a predetermined program based on input data and data stored in advance, and various states such as forward, reverse, or neutral, Further, control such as setting of the required clamping pressure and setting of the gear ratio is executed.
[0023]
Here, an example of data (signals) input to the transmission electronic control unit 22 shows a signal of the input rotational speed Nin of the continuously variable transmission 1 and a signal of the output rotational speed Nout of the continuously variable transmission 1. Is entered. Further, from an engine electronic control unit (E / G-ECU) 23 for controlling the engine 3, an accelerator opening which is a signal of an engine speed Ne, a throttle opening signal, and a depression amount of an accelerator pedal (not shown). A signal is input.
[0024]
According to the continuously variable transmission 1, the engine speed, which is the input speed, can be controlled steplessly, so that the fuel efficiency of a vehicle equipped with the engine speed can be improved. For example, the target driving force is obtained based on the required driving amount represented by the accelerator opening and the vehicle speed, and the target output necessary to obtain the target driving force is obtained based on the target driving force and the vehicle speed. The engine speed for obtaining the target output with the optimum fuel consumption is obtained based on a map prepared in advance, and the gear ratio is controlled so as to be the engine speed.
[0025]
The control device according to the present invention for the continuously variable transmission 1 described above is configured to detect a slip in the continuously variable transmission 1 and to execute control according to the detection result. An example of the control is shown in FIG. 1. First, the inflow / outflow amount Q is calculated based on the shift command value (step S1). As described above, the gear ratio is basically controlled so that the engine 3 is operated at the optimum fuel consumption. However, in addition to this, the gear ratio is controlled to a gear ratio according to an acceleration request or a deceleration request, and the gear ratio is further changed. The speed (speed change rate) is controlled. Therefore, the gear change command value takes into account the target gear ratio and the gear speed, and for example, the gear ratio that should be finally set, and the gear that changes sequentially in a transitional manner that has undergone a first-order lag process or a smoothing process for the gear ratio. The ratio is included.
[0026]
Therefore, based on the shift command value, supply / discharge of pressure oil to / from the actuator 13 on the drive pulley 11 side is controlled, and the flow rate is controlled. In other words, the flow rate of the hydraulic fluid in order gear ratios control the control of the shift command value, so depending on the configuration of the control device such as a flow rate control valve is determined in a predetermined relationship, you in the above step S1 Kerushi The probe inflow / outflow amount Q is theoretically obtained based on the shift command value.
[0027]
Next, the theoretical gear ratio change rate Δγs is calculated using the inflow / outflow amount Q calculated in step S1 (step S2). The gear ratio change rate is the amount of change in the gear ratio per unit time, and the gear ratio changes according to the amount of pressure oil flowing into or out of the actuator 13 on the drive pulley 11 side. The change rate Δγs can be obtained as the amount per unit time of the inflow / outflow amount Q obtained in step S1.
[0028]
On the other hand, the actual gear ratio change rate Δγr is calculated (step S3). In FIG. 1, this calculation is described to be performed following step S <b> 2, but the calculation may be performed in parallel with the calculation of the theoretical gear ratio change rate Δγs, and the order thereof does not matter. Further, the actual gear ratio change rate Δγr is, for example, the rotational speed of the drive pulley 11 detected by the input rotational speed sensor 20 and the rotational speed of the driven pulley 12 detected by the output rotational speed sensor 21, for example. The amount of change per unit time can be obtained. Alternatively, the actual gear ratio change rate Δγr can be obtained as the difference between the gear ratio before a predetermined time and the gear ratio at the current time point.
[0029]
Next, it is determined whether or not the absolute value (| Δγs−Δγr |) of the difference between the theoretical gear ratio change rate Δγs and the actual gear ratio change rate Δγr is greater than a predetermined value (that is, a threshold value) (step). S4). Here, the predetermined value is a value set to a minimum value with no erroneous determination in consideration of various variations including a response delay in the inflow / outflow amount Q used when the theoretical gear ratio change rate Δγs is calculated. is there.
[0030]
Further, slippage in the belt type continuously variable transmission generally occurs on the pulley side where the belt winding radius is small. Therefore, if the gear ratio immediately before slip occurs (that is, the initial gear ratio: initial γ) is different, even if the absolute value is the same, the actual slip rotation speed (the difference between the belt speed and the pulley rotation speed). ) Will be different. Specifically, when the absolute values are the same, the smaller the gear ratio, the greater the slip rotation speed. Therefore, as shown in FIG. 2, the predetermined value used in step S4 is set to a smaller value as the initial gear ratio is smaller.
[0031]
If slippage occurs in the continuously variable transmission 1 during acceleration, a downshift based on an acceleration request is instructed, and the rotational speed of the drive pulley 11 increases due to the slip, so that the actual speed ratio change rate Δγs is greater than that. The gear ratio change rate Δγr increases. Further, when the vehicle is in a driven state at the time of deceleration, if the slippage of the continuously variable transmission 1 occurs at that time, the rotational speed of the drive pulley 11 decreases, so the actual gear ratio changes to the upshift side, and The rate of change changes. In either case of the downshift and the upshift, the absolute value described above becomes large, so that a positive determination is made in step S4. On the contrary, if slip does not occur, the absolute value becomes equal to or less than a predetermined value, and a negative determination is made in step S4.
[0032]
That is, if the determination in step S4 is affirmative, the determination of slippage in the continuously variable transmission 1 has been established, and in this case, processing corresponding to the determination of belt slipping is performed ( Step S5). This processing is basically processing for preventing or suppressing belt slip, and specifically, control for increasing the clamping pressure of the continuously variable transmission 1. In addition to this, it is possible to execute control for temporarily reducing the input torque to the continuously variable transmission such as the engine torque. On the other hand, when a negative determination is made in step S4, the slip determination of the continuously variable transmission 1 is not established, so the routine of FIG. 1 is temporarily terminated without performing any particular control.
[0033]
Therefore, according to the slip detection device of the present invention that executes the control shown in FIG. 1, the absolute value of the comparison result between the actual value and the theoretical value regarding the gear ratio, specifically, the actual gear ratio change rate and the theoretical gear ratio. Since slip is determined based on the absolute value of the difference from the rate of change, slippage may occur during engine braking or regenerative braking in a hybrid vehicle, even if the gear ratio changes in the upshift direction. The slip generated in the step transmission 1 can be detected accurately or reliably. In addition, instead of simply comparing the measured value and the theoretical value as described above, if configured to be compared with a predetermined threshold as described above, variations in hydraulic pressure and response delays are reflected in the threshold. Therefore, it is possible to determine the slip more accurately. Further, if the threshold is set to a different value depending on the gear ratio such as the initial gear ratio, the slip determination can be performed in consideration of the actual slip rotation speed or the slip speed that does not appear in the absolute value. It is possible to detect a certain amount of slippage or damage with respect to the damage or durability of the step transmission 1.
[0034]
Here, the relationship between the above specific example and the present invention will be briefly described. The functional means in step S4 shown in FIG. 1 corresponds to the absolute value calculating means and the slip determining means in the present invention. The functional means corresponds to the slip countermeasure control means in this invention.
[0035]
Note that the continuously variable transmission targeted in the present invention is not limited to the belt-type continuously variable transmission shown in FIG. 3, and may be a traction type continuously variable transmission. Further, the actual measurement value and the theoretical value related to the gear ratio in the present invention may be a gear ratio in addition to the gear ratio change rate described above.
[0036]
【The invention's effect】
As described above, according to the first aspect of the present invention, a predetermined threshold is set based on the absolute value of a value obtained by comparing a difference or ratio between a measured value such as a gear ratio and a gear ratio change rate and a theoretical value. since the comparison result slip Rino generated by such a value is determined not only slip rotational speed of the input side of the continuously variable transmission is increased, and slip revolution speed of the input side is decreased, various operating conditions slippage differently can be output reliably detected.
[0037]
According to the invention of claim 2, the absolute value of the difference between the actual gear ratio change rate and the theoretical gear ratio change rate is compared with a predetermined threshold value, and the threshold value is used as the gear ratio. Because it is set to a different value on the basis of this, it is possible to judge the slip according to the actual slip rotation speed, and it is possible to accurately detect a slip that has more than a certain impact on damage or durability regardless of the speed ratio. Can be detected.
[0038]
Further, according to the invention of claim 3, when the occurrence of slip is determined, the clamping pressure is increased and the transmission torque capacity of the continuously variable transmission is increased. It is possible to prevent damage to the machine and deterioration of durability.
[Brief description of the drawings]
FIG. 1 is a flowchart for explaining an example of control by a slip detection device of the present invention.
FIG. 2 is a diagram conceptually showing the relationship between a threshold for determining slip and an initial gear ratio immediately before the start of slip.
FIG. 3 is a diagram schematically showing a drive system including a continuously variable transmission targeted by the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Continuously variable transmission, 11 ... Drive pulley, 12 ... Driven pulley, 15 ... Belt, 18 ... Drive wheel, 22 ... Electronic controller for transmission (CVT-ECU).

Claims (3)

In slippage detection device for a belt type continuously variable transmission that can the be varied steplessly variable speed ratio by changing the winding radius of the belt in accordance with the inflow out of the pressure oil against the sheave,
From the actual transmission ratio change rate obtained as the amount of change per unit time of the ratio between the input side rotational speed and the output side rotational speed and the flow rate of pressure oil flowing into and out of the sheave calculated based on the shift command An absolute value calculating means for obtaining an absolute value of a difference from the required theoretical transmission ratio change rate ;
A continuously variable transmission comprising: the slip determining means including determining slip based on a comparison result between the absolute value obtained by the absolute value calculating means and a predetermined threshold value. Slip detection device. The slippage determining means, slip detecting device for a continuously variable transmission according to claim 1, characterized in that it comprises the above-means to vary based on the threshold to the transmission ratio.   The continuously variable transmission is configured such that the transmission torque capacity changes according to the clamping pressure, and a slip countermeasure control means is provided for increasing the clamping pressure when slippage is determined by the slip determination means. The slip detection device for a continuously variable transmission according to claim 1 or 2, characterized by comprising:

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