JPS62255241A - Stepless speed changer control device - Google Patents

Abstract

PURPOSE:To provide quick engine braking effect even during high-speed operation by controlling the speed change ratio of a stepless speed changer on the basis of a specific speed change control characteristic, in which the engine load and the target number of input shaft revolutions of the stepless speed changer are used as parameters. CONSTITUTION:A control unit 101 controls the speed change ratio of a stepless speed changer 4 installed in the drive system of an engine 1. That is, the control unit 101 enters detection signals from sensors 102-109, which are to sense the operating conditions of the engine 1, and emits control signals to a clutch solenoid valve, speed change solenoid valve, etc. Here the target number of revolutions of the input shaft 81 of stepless speed changer 4 and the load of the engine 1 on the basis of the opening of throttle valve 9 are used as parameters, and the target number of revolutions is decreased in accordance with decreasing engine load, and the speed change control characteristics are set so that the target number of revolutions when the engine load is zero, increases to the specified value.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention provides a method for determining the gear ratio of a non-operating transmission interposed in an engine drive system based on the engine load expressed by the throttle valve opening, etc., and the input shaft of the transmission. The present invention relates to a control device for a transmission that performs control based on a shift control characteristic that uses a target rotation speed as a parameter.

(Prior Art) As one of the transmissions that are interposed in the drive system of the engine in order to efficiently transmit the output of the engine of an automobile etc. to the wheels, it is described in, for example, Japanese Patent Laid-Open No. 60-95258. There is known a belt-type continuously variable transmission that can continuously and steplessly change the gear ratio within a predetermined range.

In such a continuously variable transmission, as described in the above-mentioned publication, generally the shift control characteristics as shown in FIG. Using the shaft target rotation speed (target input rotation speed) TNp as a parameter, the target input rotation speed TNp decreases as the valve opening Th decreases (in this case, the decrease in TNp includes unchanged TNp). Based on the speed change control characteristics set to The gear ratio is controlled so that For example, if the input rotational speed reaches N1)IIL at a certain point in time with the throttle valve opening Th1 in the figure, the gear ratio control will shift down the transmission and increase the gear ratio so that the rotational speed becomes TN91. is performed, and the rotation speed is NDt.
In the case of b, on the other hand, gear ratio control is performed to shift up the transmission and increase the gear ratio so that the rotational speed becomes TNI)t.

Note that the gear ratio here means the number of revolutions of the input shaft of the transmission divided by the number of revolutions of the output shaft of the transmission. Also,
The characteristics shown in FIG. 10 above are speed ratio control characteristics determined in consideration of fuel economy and the like.

(Problem to be solved by the invention) However, based on the above characteristics, the above method,
In other words, in a control system that always maintains the transmission input rotation speed Np at a target input rotation speed TNI corresponding to the throttle valve opening for a certain throttle valve opening, for example, when the accelerator is turned on by pressing the accelerator, If the accelerator is released from the accelerator OFF state, sufficient engine braking may not be obtained, or the transmission may shift up and the vehicle may accelerate slightly, albeit momentarily, causing the driver's accelerator operation to be interrupted. There may be an inconvenience that the vehicle moves in a manner contrary to the above.

That is, as shown in FIG. 11, which shows the relationship between the vehicle speed V (corresponding to the output shaft rotation speed of the transmission) and the input shaft rotation speed Np of the transmission, the gear ratio change range of the transmission is defined as A. In this case, for example, if the vehicle is started with the aforementioned valve opening degree of 7hl, the relationship between the above-mentioned ■ and Nl) will be as shown by arrow B. That is, N1) along the maximum shifting line (line corresponding to LQW of manual shifting) until reaching ff1TNp1.
As p increases and exceeds TNOt, it enters the upshift region as mentioned above, so from then on, the vehicle speed V increases by continuing to shift up while maintaining TNpl, and the gear ratio minimum line (corresponding to overdrive OD of manual shifting) When the gear reaches the line ), it is impossible to shift up any further, so Np and V increase along that line. When driving on the minimum gear ratio line in this way, if the accelerator is turned off and the throttle valve opening is fully closed, Nl) will move along the minimum gear ratio line as shown by arrow C in the figure. Target input rotation speed T when the throttle valve is fully open! It enters the downshift region only when the vehicle speed drops to 'Jl)o (see Figure 10).Therefore, engine braking is not applied in the high vehicle speed region until entering this downshift region, and below that, the low vehicle speed region 1i
Engine braking begins to occur only after entering 1E. For example, if you turn off the accelerator while driving steadily below the midpoint in Figure 11, the gear ratio will not be at its minimum at this point, so turning the accelerator off will result in an upshift. For example, as shown by arrow G, the gear ratio is shifted up until it is at its minimum, and then the same path as shown in arrow C is followed, and in this case, the engine brake does not work when the accelerator is turned off. Not only that, but it also shifts up momentarily, and if anything, the vehicle is in a state of acceleration.

FIG. 12 is a time chart showing an example of upshifting when the accelerator is turned off.

In view of the above circumstances, an object of the present invention is to provide a continuously variable transmission capable of controlling the gear ratio of the continuously variable transmission so that engine braking is applied immediately or quickly even when the accelerator is turned off in a high vehicle speed range. Our objective is to provide a control device for

(Means for solving the problem) In order to achieve the above-mentioned purpose, the control device for the continuously variable transmission according to Akira Kimi is designed to
When the target input rotation speed TNI) decreases as h decreases and the engine load is substantially zero, for example, this corresponds to when the throttle valve is fully open (when the accelerator is in the OFF state), and the throttle valve opening does not necessarily change. TNI) <=”, !'It) o
> is characterized in that the gear ratio is controlled based on a gear change control characteristic set to increase up to a predetermined value.

In other words, the water control device has a control characteristic that is the basis of control, and as in the past, the TI'n increases as the engine load decreases.
JI) also decreases, and when the engine load is virtually zero, T
Not the characteristic where Np is minimum, but the TNp (-
This is achieved by adopting a characteristic in which TNI)o) is shifted in the increasing direction.

(Effects of the Invention) Since the control device for the continuously variable transmission according to the present invention performs control based on the shift control characteristics as described above, when the accelerator is changed from the accelerator ON state to the accelerator OFF state, the accelerator is turned off.
Since the target input rotation speed TNI)a in the F state is set higher than before, if the input shaft rotation speed Nl) when the accelerator is in the OFF state is smaller than that TNI)o, the shift is directly shifted to the downshift region. , and the Np is shifted down to increase to TNpO, so engine braking can be applied.
If it is larger than fiTNpo, engine braking cannot be applied immediately, but since the time for Nl) to decrease to TNpo is shorter than before, engine braking can be applied quickly, and as a result, compared to before. This allows engine braking to be applied even at higher vehicle speeds.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing an example of an engine drive system for an automobile, which includes a control device according to the present invention, a continuously variable transmission, etc. controlled by the control device.

In FIG. 1, 1 is an engine, and the output (rotation) of the engine 1 is transmitted through a clutch 2, a gearbox 3, a continuously variable transmission 4. The power is transmitted to the drive wheels 6 via the differential gear 5, and the power transmission mechanism from the engine 1 to the drive wheels 6 constitutes an engine drive system.

An intake pipe 8 is connected to the engine 1 via an intake manifold 7, and by adjusting the opening degree of a throttle valve 9 disposed within the intake pipe 8, the output of the engine 1 is adjusted. Further, as will be described later, the gearbox 3 can be manually operated to switch between R (reverse), N (neutral), D (drive), and L (low) ranges. In general, the engagement and disengagement of the clutch 2 and the control of the gear ratio of the continuously variable transmission 4 are automatically performed as will be described later by controlling actuators using hydraulic pressure.

Next, the Menji clutch 2. Gearbox 3. The variable speed transmission 4 will be explained in sequence based on FIG. It has a shaft 22.

A clutch disc 23 is spline-fitted to the clutch output shaft 22, and by press-contacting the clutch disc 23 to a flywheel 24 that is integrated with the clutch input shaft 21, a connected state is established in which both shafts 21 and 22 are connected. , conversely, the clutch disc 23 and flywheel 24
When the two shafts 21 and 22 are separated from each other, the shafts 21 and 22 are disconnected from each other, resulting in a disconnected state. In order to press the latch disk 23 against and separate from the flywheel 24 in this manner, a sleeve 25 is slidably and rotatably fitted to the output shaft 22. One end of a spring member 27 such as a disc spring, which can swing freely around center point 6, is connected to a clutch pressure plate 28, the other end of which is connected to a clutch pressure plate 28, which faces the back surface of the clutch disc 23. is connected to. As a result, when the sleeve 25 moves to the left in FIG. 2, the clutch pressure plate 28''f becomes the clutch disc 23 via the spring member 27, and the clutch disk 23 becomes connected to the left in the figure, and vice versa. When the sleeve 25 moves to the left in FIG. 2, it enters the cutting state.

The displacement position of the sleeve 25 in the leftward direction in FIG. 2 is adjusted by a cylinder device 29. That is, the piston rod 30 of the cylinder device 29 is connected to one end of a swinging arm 32 that is swingable about a fulcrum 31, while the swinging arm 3? The other end is attached to the back surface of the sleeve 25. Further, the oil hole 34 defined by the piston 33 of the cylinder device 29 is
It is connected to a taratch solenoid valve 36 consisting of a three-way electromagnetic switching valve via a pipe 35, and the taratch solenoid valve 36 is connected to a pipe 3 extending from the discharge side of a hydraulic pump 37.
8, and piping 40 extending from the reservoir tank 39,
A filter 41 is connected to the suction side of the hydraulic pump 3T, and a reservoir tank 39 is connected to the suction side of the hydraulic pump 3T.
A pipe 42 that extends further is connected.

The taratch solenoid valve 36 has two solenoids 36a and 36b for connection and disconnection, and when the connection solenoid 36a is energized (the disconnection solenoid 36b is demagnetized), the hydraulic pump 37 and the cylinder device 29 are activated. oil =
34, the piston rod 30 is extended,
Clutch 2 is connected. The transmission torque of the clutch 2 during this connection increases as the amount of oil supplied to the oil tank 34 increases (the lifting force of the clutch disc 23 on the flywheel 24 increases). Also, the disconnection solenoid 36b is energized (the connection solenoid 36
When a is demagnetized), the oil tank 34 is released into the reservoir tank 39, the piston rod 30 is retracted by the return spring 43, and the clutch 2 is disengaged.

Roughly speaking, when both solenoids 36a and 36b are demagnetized, the oil pipe 34 is in a sealed state, and the piston rod 30 is maintained as it is.

The gearbox 3 has an input shaft that has a clutch output @2.
2, and a first gear 51 and a second gear 52 having a smaller diameter than the first gear 51 are integrally formed on the clutch output shaft 22. A gearbox output shaft 53 is disposed parallel to the output shaft 22, and a back gear 54 that constantly meshes with the second gear 52 is disposed between the two shafts 22 and 53. has been done. A large-diameter intermediate gear 55 that constantly meshes with the first gear 51 is rotatably fitted to the gearbox output shaft 53, while the sleeve 5
6 are integrated. A clutch gear 57 is always spline-fitted to this sleeve 56.
As shown in FIG. 2, the clutch gear 57 can also be spline-fitted to the intermediate gear 55 as it is displaced in the axial direction.

In such a gearbox 3, when the clutch gear 57 is at the rightmost position as shown in FIG. 2, the rotation of the clutch output shaft 22 is caused by the rotation of the first gear 51. Intermediate gear 55. Clutch gear 57. It is transmitted to the gearbox output shaft 53 via the sleeve 56, and the rotational direction of the output shaft 53 at this time corresponds to the forward direction of the automobile.

Furthermore, when the clutch gear 57 is displaced to the leftmost position in FIG.
．． Back gear 54. Clutch gear 57. It is transmitted to the gearbox output shaft 53 via the sleeve 56, and the rotational direction of the output shaft 53 at this time corresponds to the backward direction of the automobile. Roughly speaking, when the clutch gear 57 is at the intermediate stroke position in the left-right direction in FIG. 2 and the gearbox output shaft 53 are cut off, resulting in a neutral state.

The displacement position of the clutch gear 57 is adjusted by a cylinder device 58. That is, a piston rod 59 of the cylinder device 58 is linked to the clutch gear 57 via an interlocking arm 60, and the piston rod 59 is connected to the clutch gear 57 via an interlocking arm 60. When the clutch gear 59 is extended, the clutch gear 57 is displaced to the left in FIG. This cylinder device 58 has two oil pumps 62 by means of its piston 61.
．． 63 is defined, and the oil outlet 62 is connected via a pipe 64, and the oil palm 63 is connected via a pipe 65 to a manual valve 66 consisting of a three-way switching valve. and,
The manual valve 66 is connected to the oil field pump 37 via a pipe 67 and to the reservoir tank 39 via a pipe 68.
are connected to each.

Such a manual valve 66 is switched by manually operating an operating lever 70 that is swingable about a fulcrum 69. The operating lever 70 is pivoted clockwise in FIG. As the temperature increases, the R range, N range, and D range are sequentially changed.

It is designed to be able to take the L range. In this R-shin 2 position 6, the oil chamber 62 is communicated with the hydraulic pump 37, and the oil chamber 63 is opened to the reservoir tank 39, so that the piston rod 59 is extended and the gearbox 3 is in the backward state. becomes. Also, in the N range position,
Both parts 62 and 63 are opened to the reservoir tank 39, and due to the balancing action of the return spring 71, the piston rod 59, that is, the clutch gear 57 is placed in the intermediate stroke position, and the gear box 3 is placed in the aforementioned neutral position.

Roughly speaking, in the D-shin 9 position, the oil chamber 62 is opened to the reservoir tank 39, the oil chamber 63 is communicated with the hydraulic pump 37, the piston rod 59 is retracted, and the gearbox 3 is moved as described above. It is in a state of forward movement.

Note that when the L-thin 9 position is selected, the manual valve 66 is at the same position as the D range.

The continuously variable transmission 4 has an input shaft 81 and an output shaft 8 that are parallel to each other. A primary pulley 83 is provided on the input shaft 81, a secondary pulley 84 is provided on the output shaft 82, and a belt 85 is wound between the two pulleys 83 and 84. . The primary pulley 83 is connected to the input shaft 81
It consists of a fixed flange 86 that is integral with the input shaft 81, and a movable flange 87 that can be slidably displaced with respect to the input shaft 81. As the fixed flange 86 approaches, the winding radius of the belt 85 around the primary pulley 83 becomes larger. Similarly to the primary pulley 83, the secondary pulley 84 also includes a fixed flange 89 that is integrated with the output 182, and a movable flange 90 that is slidable relative to the output shaft 82.
The movable flange 90 approaches the fixed flange 89 as the amount of oil supplied to the hydraulic actuator 91 increases, and the secondary pulley 84 of the belt 85
The winding radius is made larger.

The hydraulic actuator 88 is connected to the three-way N via a pipe 92, and the hydraulic actuator 91 is connected to the three-way N via a pipe 93.
They are respectively connected to speed change solenoid valves 94 which are magnetic switching valves, and the speed change solenoid valves 94 are connected to the hydraulic pump 37 via a pipe 95 and to the reservoir tank 39 via a pipe 96, respectively.

The speed change solenoid valve 94 has two valves, one for speed increase and one for deceleration.
When the speed increase solenoid 94a is energized (the deceleration solenoid 94b is demagnetized), the hydraulic actuator 88 is communicated with the hydraulic pump 37, and the hydraulic actuator 91 is opened to the reservoir tank 39. Therefore, ■ the winding radius of the belt 85 around the primary pulley 83 becomes larger, while the winding radius around the secondary pulley 84 becomes smaller, and the output shaft 82 enters a speed increasing state where its rotational speed increases (speed ratio) Conversely, when the deceleration solenoid 94b is energized (the speed increase solenoid 94a is demagnetized), the hydraulic actuator 91 is communicated with the hydraulic pump 37, and the hydraulic actuator 88 is opened to the reservoir tank 39. , ■ The winding radius of the belt 85 around the primary pulley 83 becomes smaller, while the winding radius around the secondary pulley 84 becomes larger, so that the output shaft 8? enters a deceleration state in which the rotational speed decreases (speed ratio is large). Roughly speaking, when both solenoids 94a and 94b are demagnetized, ■Belt 8
The winding radius for both pulleys 83 and 84 of belt 5 remains unchanged (speed ratio fixed). Of course, the speed ratio is the rotation speed of the input shaft 81 divided by the rotation speed of the output shaft 82 (belt 8
5 divided by the winding radius for the secondary pulley 84 by the winding radius for the primary pulley 83).

Incidentally, reference numeral 97 in FIG. 2 is an electromagnetic relief valve, which continues to maintain the illustrated position during clutch control and gear ratio control, which will be described later.

1 and 2, reference numeral 101 denotes a control unit, to which the outputs from the respective sensors 102 to 109 are input, and from the control unit 101, the clutch solenoid valve 36. Speed change solenoid valve 94. It is output to the relief valve 97. Each of the sensors 102 to 10
9, the sensor 102 is a throttle sensor that detects the opening degree of the throttle valve 9. The sensor 103 is a rotation speed sensor that detects the rotation speed NE of the engine 1 (in the embodiment, the same as the rotation speed E of the clutch input shaft 21). The sensor 104 is a rotation speed sensor that detects the rotation speed C of the clutch output shaft 22. The sensor 105 is a position sensor that detects the R, N, D, and L positions of the operating lever 70. The sensor 106 is connected to the continuously variable transmission 4
The user sensor 107 is a rotation speed sensor that detects the rotation speed NO of the input shaft 81 of the continuously variable transmission 4, and is a vehicle speed sensor that detects the rotation speed of the output shaft 82 of the continuously variable transmission 4, that is, the vehicle speed. sensor 1
08 is an accelerator sensor for detecting the opening degree of the accelerator pedal 110. Sensor 109 is a brake sensor for detecting whether brake pedal 111 is being operated.

Next, the content of control by the control unit 101 will be explained based on FIGS. 3 to 8. FIG. 3 is a flowchart showing the entire processing system. Various data necessary for control are input in S2, and then clutch control in step S3 and gear ratio control in step 84 are performed (j; In the following explanation, we will emphasize the routine for clutch control and the routine for speed ratio control.

(2) Clutch Control Routine (FIG. 4) First, in step 121, it is determined whether or not the operating lever 70, that is, the gearbox 3, is in the N range. If it is not in the N range, the process moves to step 122. In this step 122, it is determined whether the vehicle speed is high (for example, 1ONu/h or more). If the vehicle speed is high, a vehicle speed flag is set in step 123, and then step 124
Move to.

In step 124, the differential value E' of the rotation speed E of the clutch input shaft 21 is determined, and it is determined whether the differential value E' is positive indicating an increase in the rotation speed. If so, the process moves to step 125. This step 1
25, it is determined whether or not the rotation speed E of the clutch input shaft 21 is larger than the rotation speed C of the clutch output shaft 22.
>C, the process moves to step 126. Then, in step 126, the connection solenoid 36a of the taratch solenoid valve 36 is energized, while the disconnection solenoid 36b is deenergized to connect the clutch 2, that is, increase its transmission torque. Also, in step 125, E
If it is determined that the condition is not C, the process proceeds to step 128, where the connecting and disconnecting solenoid valves 36a and 36b of the taratch solenoid valve 36 are both demagnetized to maintain the transmitted torque of the clutch 2 as it is.

If it is determined in step 124 that E'>0 is not the case, the process moves to step 127, where it is determined whether E<C. When Etc, the process moves to step 126, clutch 2 is connected, and Etc is reached again.
If not, the process moves to step 128 and the connected state of the clutch 2 is maintained as it is.

The flow from step 124 to 125 described above is based on the assumption that the rotation of the clutch input shaft 21 is increasing, and the flow from step 125 to 126 is based on the assumption that the rotation of the clutch input shaft 21 is increasing. Since the rotation speed C of clutch output shaft 22 is higher than the rotation speed C of clutch output shaft 22, it is necessary to increase the transmission torque of clutch 2. Therefore, the connection is performed in order to increase the transmission torque of clutch 2. be. This case corresponds to, for example, a so-called half-clutch state when starting an automobile. Further, since the flow from step 125 to step 128 is when the transmission torque of the clutch 2 is exactly balanced, the clutch 2 is held in that state, and in this case, for example, it corresponds to a steady running state. .

Conversely, the flow from step 124 to step 127 is based on the assumption that the rotational speed of the clutch input shaft 21 is decreasing, and the transfer of torque between the clutch input and output shafts 21 and 22 is performed from step 124 to step 125. Since the flow is opposite to that of step 125, the decision made in step 127 is
In contrast to the determination in , it is checked whether E<C. Note that the flow from step 127 to step 126 corresponds to, for example, a case where the control lever 10 is changed to D range while driving with the control lever 10 set to N range, and in this case also a so-called half-clutch state is formed. do. Further, the flow from step 127 to step 128 corresponds to a deceleration running state using engine braking, for example.

On the other hand, if it is determined in step 121 that the vehicle is in the N range, the vehicle speed flag is reset in step 129, and then the process proceeds to step 130. This step 13
At 0, the connection solenoid 36a of the clutch solenoid valve 36 is deenergized, while the disconnection solenoid 36b is energized to disconnect the clutch 2.

In other words, in this case, it is clear that the driver himself requests a neutral state, so clutch 2 is unconditionally applied.
cut.

Also, step 12? If it is determined that the vehicle speed is low, the process moves to step 131, where the accelerator pedal 1 is
It is determined whether or not O1'J is stepped on. When the accelerator is not ON, that is, when it is OFF, this means that no output from the engine 1 is requested, so the process moves to step 132 and it is determined whether the vehicle speed flag is set. When the vehicle speed flag is set, it means that the vehicle speed has not yet decreased sufficiently, and in this case, the process moves to step 133, where it is determined whether or not the brake pedal 111 is depressed. If the brake is ON, the process moves to step 134, where the engine speed is set to NE or 15.
If it is determined that the rpm is below 00 rpm, step 129
After that, proceed to step 130 (disconnection of clutch 2).
2 Also, if it is determined in step 133 that the brake is not turned on, the process moves to step 135, and if it is determined here that the engine rotation speed NE is 1100 Orp or less, the process proceeds to step 1 through step 9. Processing 130 is performed (clutch 2 is disengaged). Then, if the engine rotation speed NE is determined to be not less than 1500 rpm in step 134 and 11 in step 135,
If it is determined that the engine speed is not below 000 rpm, the process proceeds to step 124 and the above-mentioned processing is performed.In this way, the engine is used as the basis for determining whether or not to disengage the clutch 2 by turning the brake ON or OFF. Rotation speed N
The reason why the 8 angles of E were made different was to allow more leeway to avoid the risk of stalling, considering that the vehicle speed decreases faster when the brakes are on than when the brakes are not on. . Note that when it is determined in step 132 that the vehicle speed flag is not set, the process of step 130 is performed via step 129 to prevent the engine from stalling (clutch 2 is disengaged).

(2) Gear ratio control routine (Figure 8) This gear ratio control is performed by the control unit 101, which is a control device of the transmission, to achieve the gear change control characteristics as shown in Figure 5, that is, to reduce the throttle valve opening Th. This is done based on a control characteristic set so that the target input rotational speed T"qp ffi of the transmission decreases accordingly, and TNI) increases to a predetermined value when the throttle valve is fully open (accelerator 0FF). Of course, this is done based on the control method. As described above, upshifting and downshifting are performed so that the transmission input rotational speed Nl) always becomes TNp corresponding to Hh for each Th.

In the control characteristics shown in FIG. 5, the target input rotation speed I NOO when the throttle valve is fully open is approximately 3500 rpm.
Of course, this TNOc can be set to any value as long as it is larger than the minimum value of 111) before the throttle valve is fully opened. It may be set as a constant value unrelated to the vehicle speed V, as shown by the straight line H1, or it may be set as a function value of the vehicle speed that decreases as the vehicle speed decreases, as shown by the straight line H2. When used as a function of vehicle speed, it is desirable to change linearly as shown in the figure, but the vertical position and inclination angle of inH: in the figure can be set freely.Also, when used as a function of vehicle speed, is its TNp.

does not need to be larger than the above-mentioned minimum TNI in all vehicle speed ranges, but may be larger than the minimum TNp at least in a predetermined high speed range.

As mentioned above, by setting TNpo to a higher value than before, when the accelerator is turned from the accelerator ON to the accelerator OFF, the
It is possible to solve or reduce the problem of no engine braking or large shift up in high vehicle speed ranges.

In other words, as shown in Fig. 6, if you turn off the accelerator while driving at a steady state in the state of point 2, T! Nl) When o is set low as in the straight line J, Np and V transition as indicated by the arrow K, and as mentioned above, the engine remains unchanged until the vehicle enters the low speed range where NO is below the straight line J. There was not a single shake, but in the present invention, TNpO is set high as in the straight line H1, so if you turn off the accelerator from the state of 1.4■, Nl)
and \l transition along the arrow mark, and therefore the area where engine braking is applied immediately, that is, the downshift area T! J
, (straight line Lt, part 12 of the arrow), and therefore engine braking is activated even in a high vehicle speed range.

By the way, if we make the above T'NI') O irrelevant to the vehicle speed like the straight line H1, the accelerator O will change from the steady running time at each vehicle speed.
With FF and T = the engine brake is uneven and constant)! It's hard to get a sense of it. For example, the 6th starting point\4. When the accelerator is turned off from a steady state at 4p position of N, the arrow 0. P, Np and V change, and comparing the two, the degree of downshift < degree of increase in In, i.e. the distance from points M and N to straight line H1) is different, and there is a greater deceleration in the case of shifting to point P. You will get a feeling. However, for example, the above straight line H2
If we set o as a function of vehicle speed, as shown by Q and R, and both provide similar deceleration sensations.

Roughly speaking, if the above TNI) is set like the straight line H2, although it can be done if it is set like the straight line H1, the engine brake is too sharp in the low vehicle speed range, that is, the gear ratio shifts too quickly to the maximum line side. As it becomes a trend,
In order to improve this, the slope of the straight line may be made steeper (almost) in the low vehicle speed range, for example, as shown by the dashed line H2'.

By the way, the difference in the sense of deceleration between the above points M and Nk is as shown in Figure 5, for example, when the accelerator is fully opened from points M and N, the degree of downshift in each case becomes line segments S and T, and the line This can also be explained by the fact that the degree of downshift is greater in the numerator.Also, the difference in the engine brake gap between the conventional and the present invention when the accelerator is fully opened from point As shown in the figure, under the assumption that the gear ratio is at its minimum, in the conventional case, engine braking begins only when Np decreases by a line segment U, but in the present invention, it decreases by a line segment W. This can also be explained by the fact that engine braking begins to occur more quickly.

Roughly speaking, as mentioned above, in this embodiment, in addition to the D range, there is also a range dedicated to engine braking.In this case, the TNpO of both ranges is determined as a function of vehicle speed, as shown in FIG. As well as the TNI of the microwave)
It is better to set it higher.

Next, as shown in FIG. 7, a control unit 101 is equipped with a gear ratio control characteristic in which TNI)o is set (this gear ratio control characteristic is stored in a memory means (not shown) built in the unit 101). An example of the gear ratio control according to the method described above will be explained according to the flowchart shown in FIG.

First, in step 221, the input rotation speed Np of the transmission is read, and in step 222, the accelerator opening α (corresponding to the throttle valve opening) is read.
Read the vehicle speed in step 3. At dawn, the vehicle speed is 1 at step 224! It is determined whether or not it is below V, m, /h, and if NO, step? 25, the sensor 102 or 1
Accelerator is ON or OFF based on information input from 08
If it is OFF, it is determined in step 226 whether or not the engine brake flag has been reset, and if YES, step 226 is performed. ? Brake is O at 7
It is determined whether it is N or OFF, and if it is OFF, step 2
Set the engine brake flag at 28 and step?
In step 29, the current vehicle speed \/ is set to Y, and in step 230, it is determined in which range of L the operating lever 70 is located, and based on the determination results, each step 231. V for D range and L range at 232
TNp <TNI)O) shown in Figure 7.
calculated from the po diagram, and in step 233 the TNp is
Then, in step 234, using the above V, Y, and X, T'
Perform the operation 4p-X*V, /Y, and step 235
The calculated TNI) is the minimum target input rotation speed T'qp
It is determined whether or not it is smaller than min (see FIG. 7), and if YES, TNpmin is set to TNp in step 236, and if NO, the process proceeds to step 237, where Np is set to TNp. It is determined whether or not it is below, and if YES, the shift is down in step 238, and if NO, the shift is up in step 239.

The downshift performed in step 238 increases the gear ratio by demagnetizing the speed increase solenoid 94a and energizing the deceleration solenoid 9Ab, and increases the input rotational speed N.
The control unit 101 outputs a downshift signal to the speed change solenoid valve 94 so as to increase O, and the upshift in step 239 is performed by energizing the speed increase solenoid 94a while energizing the deceleration solenoid 94D. to reduce the gear ratio,
This is done by outputting a shift up signal from the control unit 101 to the speed change solenoid valve 94 so as to reduce the input rotational speed Np.

Above steps? Steps 29 to 233 are for determining the initial conditions for setting TNt)(1\t)O) when the accelerator is fully engaged according to the vehicle speed, and step 22
After setting the engine brake flag and determining the initial conditions in step 8, what are the steps? 26 directly from step 234
In step 234, the TN is changed according to the change in vehicle speed.
f) Perform steps 235 to 23 while varying (TNpO).

Hey, Step? ? 4, if the vehicle speed V is determined to be 15 points, /h or less, step? ? If it is determined that the accelerator is ON in Step 5, or if it is determined that the brake is ON in Step 227, it is determined that engine braking is not required, and the process moves to Step 240.
At step 40, the engine brake flag is reset, and at step 241, TNp for α is calculated. Calculation of TN in this case is done based on Fig. 5, but since engine braking is not required, there is no need to increase TNp even when the accelerator is fully open, so TNp when the accelerator is fully closed is It is determined based on the broken line X in FIG. Once TNp is calculated in this way,
Thereafter, steps 237 to 239 described above are executed.

By the way, the gear ratio control based on the control characteristic that greatly increases the TNt when the accelerator is fully open, performed by the device of the present invention, is as follows.
This is not necessarily the case in all cases; for example, as mentioned above, such control is performed only when engine braking is required, and when it is not required, the above steps are performed. This also includes cases where control is performed based on conventional control characteristics, as in No. 41.

FIG. 9 is a time chart showing an example of the case where the above-mentioned control is used to downshift and apply engine braking when the accelerator is turned off.

As described above, the control device according to the invention performs the control 15- based on the shift control characteristic in which the target input rotation speed TNI) when the accelerator is OFF is set higher than the conventional one. In addition, the above-mentioned TNI
) By making c a function of vehicle speed and making the function a straight line, a constant sense of deceleration can be obtained from each vehicle speed. Incidentally, after reaching the above-mentioned TNI)o, the gear ratio may be fixed and the gear ratio may be reduced in some way.

The invention is also applicable to continuously variable transmissions other than the V-belt type described above. Further, the present invention can be modified in various ways without departing from the gist thereof, and is not limited to the above-described embodiments.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing an example of an engine drive system including an example of a control device according to the present invention, and Fig. 2 is a schematic diagram showing details of the control device, clutch, and continuously variable transmission shown in Fig. 1. Fig. 3 is a flowchart showing an example of the control contents by the υ control device shown in Fig. 1; Fig. 4 is a flowchart showing details of the clutch control portion in Fig. 3;
The figure shows an example of the gear change control characteristics used for the gear ratio control in Figure 3, Figure 6 is a diagram explaining the control content based on the characteristics in Figure 5, and Figure 7 is an example of TNI) o in Figure 5. Figure 8 is a flowchart showing details of the gear ratio control part in Figure 3, Figure 9 is a time chart showing an example of control according to the flowchart in Figure 8, and Figure 10 is conventional gear ratio control. A diagram showing an example of the characteristics, Fig. 11 is the 10th
FIG. 12 is a time chart showing an example of control based on the characteristics shown in FIG. 10. 1... Engine 4... Continuously variable transmission 9...
・Throttle valve 81...Transmission input shaft 101・
・・Control device Figure 9 1 o pattern - m heka prison ¥ LNP (X) 03 rpm) No. 11
Figure 12

Claims (2)

[Claims] (1) A control device for a continuously variable transmission that controls a gear ratio of a continuously variable transmission interposed in an engine drive system, the control device controlling the engine load and the target input rotation speed of the input shaft of the continuously variable transmission as parameters. and the target input rotation speed decreases as the engine load decreases, and the target input rotation speed increases to a predetermined value when the engine load is substantially zero. Based on the above, the gear ratio is controlled so that the input rotation speed of the input shaft of the continuously variable transmission becomes a target input rotation speed corresponding to the load at each engine load. Control device. (2) Control of the continuously variable transmission according to claim 1, wherein the target input rotation speed when the engine load is substantially zero is set as a function of vehicle speed. Device.