JPS61132426A - Line pressure control device in stepless speed change unit - Google Patents

Abstract

PURPOSE:To prevent a V-belt in a speed change unit from slipping by establishing a high line pressure which is set in consideration with a reference line pressure during engagement of a clutch during which the transmission torque of an engine drive system is goverend by the clutch. CONSTITUTION:A stepless speed change unit in which the gear ratio is changed by adjusting the groove gaps of drive and driven pulleys having variable effective diameters, by means of hydraulic actuator, is coupled with the output shaft of an engine through a clurch 2. In this arrangement, there are provided a clutch control means (three-way solenoid selector value) A for controlling the engagement and disengagement of the clutch 2, a line pressure regulating means B for regulating the line pressure fed to a hydraulic actuator and a line pressure control means C for controlling the regulating means B so that the line pressure becomes equal to a reference value set in accordance with the operating condition of the engine. Further, during engagement of the clutch a line pressure compensating means D compensates the line pressure to a value which is higher than the reference value.

Description

Detailed Description of the Invention (Field of Application in Industry-1-) The present invention relates to a V-belt type continuously variable transmission in which the tension of the V-belt type is set to an appropriate value. The present invention relates to a line pressure control device.

(Prior Art) Recently, a vehicle transmission using a V-belt type continuously variable transmission is being put into practice. In this V-belt type continuously variable transmission, a V-belt is wound around a driving pulley and a driven pulley, and a hydraulic actuator is used to change the groove spacing between both pulleys, that is, the widthwise spacing of the V-belt. The ratio will be changed. Continuously variable transmissions of this type have major advantages such as no shift shock and easy optimization of engine operation, resulting in fuel savings, and are expected to be used as future vehicle transmissions. There are high expectations.

By the way, considering the torque that can be transmitted by the continuously variable transmission as mentioned above, this can be promoted as the tension of the V belt, that is, the force that clamps and presses the NkV belt from the width direction by the left and right flanges of the pulley. can. To explain this point with reference to FIG. 12, the pair of left and right fixing flanges 1
The V-belt 3' sandwiched between the movable flange 2' and the movable flange 2' in the width direction
The maximum transmission force will be determined by the frictional force against a. This frictional force is expressed as follows: F is the friction coefficient of the V-belt 3' against the inclined surfaces 1a', 2a', F is the clamping force or pressing force by the flanges 1', 2', and F is the friction coefficient of the V-belt 3' against the inclined surfaces 1a', 2a'. Taking the angle as 20, the transmittable torque f determined by friction is f = 2 X g X F X cos O-(
1). The above pressing force F is the movable flange 2
'Piston 5 in hydraulic actuator 4' for operation
If the pressure-receiving area of ' is A, and the pressure acting on the piston 5', that is, the line pressure, is PL, then F = AXPL
(2) becomes. -1- (1), (
As understood from equation 2), the torque that can be transmitted by the continuously variable transmission ultimately depends on the line pressure PL, and as the line pressure increases, the torque that can be transmitted increases. This line pressure PL is obtained by adjusting the pump pressure generated by an oil pump driven by the engine using line pressure adjusting means such as a relief valve.

On the other hand, the torque that can be transmitted by the continuously variable transmission (hereinafter referred to as transmittable torque) and the torque required to drive the vehicle, i.e. the transmission required by the continuously variable transmission) Considering the relationship between V-belt slippage (V-belt slippage on pulleys), the relationship of required transmission torque ≦ transmissible torque □ (3) must be maintained at the minimum necessary. It is necessary to meet the requirements. Also, the transmittable torque, that is, V
Increasing the tension of the belt more than necessary causes the oil pump to do unnecessary work, resulting in poor fuel efficiency, and also poses a problem in the durability of the V-belt. Of course, from the viewpoint of the durability of the V-belt, it is also undesirable to cause the V-belt to slip.

For this reason, as shown in Japanese Patent Application Laid-Open No. 58-39871, line pressure has been changed according to engine torque,
It has been proposed to improve the durability of the V-belt and save fuel by minimizing the transmittable torque of the continuously variable transmission while satisfying the relationship in equation (3). To explain this point in detail, now the vehicle's drive wheels are
When we consider the case where a driving force of k is generated, the effective radius of this drive wheel is r, the effective radius of the differential gear is T3, the gear ratio of the differential gear is g, and the input torque of the differential gear is T3. The gear ratio of the continuously variable transmission is n,
If the input torque of the continuously variable transmission is T1, and the output torque of the continuously variable transmission is T2, the required transmission torque fO is: fo=FkXr/Jlj (4) - T
37 sentences □(5) = gXT27 sentences □(6) = n X g XT 1 /1-(7). As is clear from the above equations (4) to (7), especially equation (7),
Since the required transmission torque is determined by the input torque of the continuously variable transmission corresponding to the engine torque, by setting the line pressure in accordance with this engine torque, the above formula (3) can be satisfied while keeping the line pressure as low as possible. It becomes possible to satisfy the relationship.

However, in the above publication, the transmission torque of the engine drive system is only applicable to the operating range where it is dominated by the engine torque, in other words, only the operating range where the input torque T1 of the continuously variable transmission corresponds to the engine torque. In this respect, it was inadequate. To explain this point in more detail, this type of continuously variable transmission is used by being connected to the engine via a clutch, but when starting, for example, the transmission changes from a clutch disengaged state to a clutch engaged state. Considering the clutch engagement process (in the middle of engagement), the transmission torque of the engine drive system during the clutch engagement process is dominated by the transmission torque of the clutch in the engagement process. And the transmission torque (capacity) of this clutch
is set to be extremely large, approximately twice the maximum torque of a normal engine, to allow for a margin. Therefore, in the method described in the above publication, if the line pressure is set according to the engine torque during the clutch connection process, slippage will occur in the V-belt of the continuously variable transmission, which is undesirable in terms of its durability. Furthermore, if the line pressure was set uniformly according to the clutch capacity, the operation time would be too long with the line pressure being unnecessarily high, which would reduce the durability of the V-belt and reduce fuel consumption. Second, it becomes undesirable.

(Object of the invention) The present invention has been made in consideration of the above circumstances, and
A line-in pressure fl of a continuously variable transmission in which the line pressure in the clutch engagement process is optimally set to prevent slipping of the V-belt of the continuously variable transmission in the clutch engagement process.
The purpose is to provide IT control equipment.

(Structure of the Invention) In order to achieve the above-mentioned object, in the present invention, the line pressure is reduced to a high transmission torque during the clutch engagement process in which the transmission torque of the engine drive system is dominated by the transmission torque of the clutch. In order to cope with this, a predetermined reference line pressure is corrected according to the operating state of the engine to obtain a high line pressure. Specifically, as shown in FIG. 1, the system is connected to an engine via a clutch, and includes a driving pulley, a driven pulley, and a V-belt wound around both pulleys, and the grooves of both pulleys are moved by a hydraulic actuator. A continuously variable transmission that changes a gear ratio by changing an interval, comprising a clutch control means for controlling engagement and engagement of the clutch, a line pressure adjustment means for adjusting line pressure supplied to the hydraulic actuator, and an engine. line pressure control means for controlling the line pressure adjustment means so that the line pressure is set to a predetermined reference line pressure according to the rotational state of the vehicle; and line pressure correction means for correcting the reference line pressure to a higher line pressure.

With this configuration, in the operating range where the transmission torque of the engine drive system is dominated by the engine torque, it is possible to set the reference line pressure according to the engine operating condition. While it is possible to set the line pressure as low as possible within a range that does not cause slippage in the V-belt, in the clutch engagement process where the transmission torque of the engine drive system is controlled by the clutch, the above reference line pressure is By taking this into consideration and setting a high line pressure, it is possible to prevent the V-belt from slipping.

(Example) Embodiments of the present invention will be described below with reference to the accompanying drawings.

In FIG. 2 showing the overall outline, 1 is an engine, and the output (rotation) of the engine 1 is transmitted to drive wheels 6 via a clutch 2, a gearbox 3, a continuously variable transmission 4, and a differential gear 5. 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 a throttle valve 9 is disposed within the intake pipe 8.
, a fuel injection valve lO are provided. The opening degree of the throttle valve 9 is electronically controlled, and for this purpose, a throttle drive mechanism 101 is provided. Moreover, the gearbox 3, as described later,
By manual operation, R (reverse), N (neutral)
, D (drive), and L (low) ranges. Furthermore, the engagement and disengagement of the clutch 2 and the change of the gear ratio of the continuously variable transmission 4 are automatically performed as described later by controlling an actuator using hydraulic pressure.

Next, the clutch 2, gearbox 3, continuously variable transmission 4
, the throttle drive mechanism 101, and the throttle drive mechanism 101 will be sequentially explained based on FIG.

Clutch 2 The clutch 2 is of a friction type and connects a clutch input shaft 21, which also serves as a crankshaft I for the engine 1, and the input shaft 2.
It has a latch output shaft 22 that is rotatable with respect to 1.

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 way, 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 that can swing freely is connected, while the other end of the spring member 27 is connected to a clutch pressure plate 28 facing the back surface of the clutch disc 23. . As a result, when the sleeve 25 moves to the left in FIG. 3, the clutch pressure plate 28, that is, the clutch disc 23 is displaced to the left in the figure via the spring member 27, resulting in a connected state, and conversely, the sleeve 25 moves from this connected state to the left in the figure. When 25 moves to the left in FIG. 3, it enters the cutting state.

Adjustment of the leftward displacement position of the sleeve 25 in FIG. 3 is performed by a cylinder device 29 serving as a hydraulic actuator. That is, the cylinder device 29
The piston rod 30 is connected to one end of a swinging arm 32 that is swingable about a fulcrum 31, while the other end of the swinging arm 32 faces the back surface of the sleeve 25. Further, an oil chamber 34 defined by a piston 33 of the cylinder device 29 is connected to a clutch solenoid valve 36 consisting of a three-way electromagnetic switching valve via a pipe 35. It is connected to a pipe 38 extending from the side and a pipe 40 extending from the reservoir tank 39, respectively. The oil pump 37 has a filter 41 on its suction side.
is connected to a pipe 42 extending from the reservoir tank 39.

The clutch solenoid valve 36 has two solenoids 36a and 36b, one for connection and one for disconnection. 34, the piston rod 30 is extended,
Clutch 2 is connected. The transmission torque of the clutch 2 during this connection increases as the hydraulic pressure supplied to the oil chamber 34 increases (the pressure force of the clutch disc 23 against the flywheel 24 increases). Also, the disconnection solenoid 36b is energized (the connection solenoid 36
a is demagnetized), the oil chamber 34 is opened to the reservoir tank 39, the piston rod 30 is retracted by the return spring 43, and the clutch 2 is disengaged. Further, when both the solenoids 36a and 36b are demagnetized, the oil chamber 34 is sealed and the piston rod 30 is maintained as it is.

Gearbox 3 The gearbox 3 has an input shaft that is connected to the clutch output shaft 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. ing. A large-diameter intermediate gear 55 that constantly meshes with the first gear 51 is rotatably fitted to the gearbox output shaft 53, and a sleeve 56 is integrated therein. A clutch gear 57 is always spline-fitted to this sleeve 56, and as the clutch gear 57 is displaced in the axial direction,
As shown in FIG. 3, spline fitting is also possible for the intermediate gear 55.

In such a gearbox 3, when the clutch gear 57 is at the rightmost position as shown in FIG. 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. Also, clutch gear 5
7 to the leftmost position in FIG. 3, the rotation of the clutch output shaft 22 is transmitted to the gearbox output shaft 53 via the second gear 52, back gear 54, clutch gear 57, and sleeve 56. , the rotational direction of the output shaft 53 at this time corresponds to the backward direction of the automobile. Furthermore, when the clutch gear 57 is at the intermediate stroke position in the left-right direction in FIG. A neutral state is established in which interlocking with the gearbox output shaft 53 is cut off.

The displacement position of the clutch gear 57 is adjusted by a cylinder device 58 as a hydraulic actuator. That is, the piston rod 59 of the cylinder device 58 is linked to the clutch gear 57 via the interlocking arm 60, so that when the piston rod 59 is extended, the clutch gear 57 is displaced to the left in FIG. It has become. This cylinder device 58 has two oil chambers 62 and 63 defined by its piston 61.
2 is connected to a manual valve 66, which is a three-way switching valve, through a pipe 64, and the oil chamber 63 is connected to a manual valve 66, which is a three-way switching valve, through a pipe 65. And the manual valve 66 is
to the oil pump 37 via a pipe 67;
8 to the reservoir tank 39, respectively.

Such a manual valve 66 is switched by manually operating an operating lever 70 that can swing freely around a fulcrum 69. The operating lever 70 swings toward the leftmost direction in FIG. As the range increases, the R range, N range, D range, and L range can be taken sequentially.

In this R range position, the oil chamber 62 is communicated with the oil pump 37, and the oil chamber 63 is connected to the reservoir tank 3.
9, the piston rod 59 extends and the gearbox 3 enters the backward state. In addition, in the N range position, both sleeve chambers 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 in the intermediate stroke position, and the gearbox 3 is the neutral position described above. Further, in the D range position, the oil chamber 62 is opened to the reservoir tank 39, the oil chamber 63 is communicated with the oil pump 37, the piston rod 59 is retracted, and the gearbox 3 moves forward as described above. state. In addition, when in the L range position, the manual valve 66 is in the same position as in the D range, and the valve 66 is used to issue a request for engine braking, which will be described later. i4 has an input shaft 81 and an output shaft 82 that are parallel to each other, and a drive pulley 83 is attached to the input shaft 81.
Further, a driven pulley 84 is provided on the output shaft 82, and a belt 85 is wound between the pulleys 83 and 84. The drive pulley 83 is composed of a fixed flange 86 that is integral with the input shaft 8.1 and a movable flange 87 that can be slidably displaced with respect to the input shaft 81.
approaches the fixed flange 86 as the hydraulic pressure supplied to the hydraulic actuator 88 increases, and the winding radius of the belt 85 around the drive pulley 83 increases. Similarly to the drive pulley 83, the driven pulley 84 also includes a fixed flange 89 that is integrated with the output shaft 82, and a movable flange 9 that can be slidably displaced with respect to the output shaft 82.
As the hydraulic pressure supplied to the hydraulic actuator 91 increases, the movable flange 90 approaches the fixed flange 89 so that the winding radius of the belt 85 around the driven pulley 84 becomes larger. has been done.

The hydraulic actuator 88 is connected to a speed change solenoid valve 94, which is a three-way electromagnetic switching valve, through a pipe 92, and the hydraulic actuator 91 is connected to a speed change solenoid valve 94, which is a three-way electromagnetic switching valve, through a pipe 95. It is connected to the oil pump 37 and to the reservoir tank 39 via piping 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 8B is communicated with the oil pump 37, and the hydraulic actuator 91 is opened to the reservoir tank 39. (1) The winding radius of the belt 85 around the driving pulley 83 becomes large, while the driven pulley 8
4 becomes smaller, and the output shaft 82 enters a speed increasing state where its rotational speed increases (speed ratio is small). Furthermore, when the deceleration solenoid 94b is energized (the speed increase solenoid 94a is demagnetized), the hydraulic actuator 91 is connected to the oil pump 37, and the hydraulic actuator 88 is opened to the reservoir tank 39, so that the V The winding radius of the belt 85 around the driving pulley 83 becomes smaller, while the winding radius around the driven pulley 84 becomes larger.
The output shaft 82 enters a deceleration state in which its rotational speed decreases (speed change Hokuten). Of course, the speed ratio is the rotation speed of the input shaft 81 divided by the rotation speed of the output shaft 82 (the winding radius of the V-belt 85 around the driven pulley 84 divided by the winding radius around the drive pulley 83). .

When both solenoids 94a and 94b are demagnetized, line pressure regulated by a relief valve 97 (described later) is supplied to the actuator 91 on the driven pulley 84 side via the throttle 94c. , the actuator 88 on the drive pulley 83 side is sealed, thereby
A tension corresponding to the line pressure is applied to the V-belt 85 while the gear ratio is set to a predetermined speed ratio. The line pressure is supplied to the driven pulley 84 by the continuously variable transmission 4 acting as a speed reducer.
This is because the torque reached is larger than that on the drive pulley 83 side.
Furthermore, the reason why the actuator 88 on the drive pulley 83 side is sealed is to prevent the set speed ratio from changing.

Throttle drive mechanism ioi The throttle drive mechanism 101 includes a throttle valve 9
Cylinder device 10 as a hydraulic actuator for driving
2. This cylinder device 102 has two oil chambers 104 .
105 is defined, and a piston rod 106 extending from the piston 103 is connected to the throttle valve 9. ”The oil chamber 104 is connected to the oil chamber 1 via the piping 107.
05 is connected to the three-way electromagnetic switching valve 1 through the pipe 108, respectively.
This switching valve 109 is connected to the oil pump 37 via a pipe 110 and to the reservoir tank 39 via a pipe 111.

As a result, the two solenoids 109a of the switching valve 109
, 109b, when the solenoid 109a for increasing the opening degree is energized (the solenoid 109b is demagnetized), the oil chamber 1
04, the oil chamber 105 is opened to the reservoir tank 39, and the opening degree of the throttle valve 9 is increased. Conversely, when the opening reduction solenoid 109b is energized (the solenoid 109a is demagnetized), oil is supplied to the oil chamber 105, while the oil chamber 104 is opened to the reservoir tank 39, and the throttle valve 9 is opened. degree is reduced. And both Tsureido 109a, 109b
When both the sleeve chambers 104 and 105 are sealed, the opening degree of the throttle valve 9 is maintained.

The oil pressure discharged from the oil pump 37, that is, the pump pressure, is regulated to a predetermined line pressure as described later by a relief valve 97 serving as a line pressure regulating means, and then the pressure is adjusted to a predetermined level of line pressure as described below. .66.94
．． 109.

In FIGS. 2 and 3, reference numeral 131 is a control unit, to which the outputs from each sensor 132 to 141 are input, and from the control/roll unit 131, a clutch solenoid It is output to the valve 36, the speed change solenoid valve 94, the relief valve 97, and the electromagnetic valve switching 109.

To explain each of the sensors 132 to 141, the sensor 132 is a throttle sensor that detects the opening degree of the throttle valve 9. The sensor 133 is a rotation speed sensor that detects the rotation speed NE of the engine 1 (same as the rotation speed E of the clutch input shaft 21 in the embodiment). Sensor 13
4 is a rotation speed sensor that detects the rotation speed C of the clutch output shaft 22. The sensor 135 is connected to R5 of the operating lever 70.
This is a position sensor that detects the N, D, and L positions.

The sensor 136 is a rotation speed sensor that detects the rotation speed NP of the input @1181 of the continuously variable transmission 4.

The sensor 137 detects the rotation speed N of the output shaft 82 of the continuously variable transmission 4.
s, that is, a vehicle speed sensor that detects vehicle speed V. Sensor 138 is an accelerator sensor for detecting the opening degree of accelerator pedal 142. Sensor 139 is a brake sensor for detecting whether brake pedal 143 is being operated. The sensor 140 is a fuel amount sensor that detects the amount of fuel supplied to the engine 1, for example, by detecting a control pulse corresponding to the amount of fuel injection supplied to the fuel injection valve 10. The sensor 141 is a slope sensor that detects the slope of the road surface on which the vehicle is running.

Next, the contents of control by the control unit 131 will be explained in order based on the flowcharts shown in Figs. 4 to 6 and Fig. 1O, dividing them into overall control, clutch control, gear ratio and throttle control, and line pressure control. do.

Overall control (Figure 4) Figure 4 shows the overall processing system.
After the system is initialized in step 1, various data necessary for control are input in step 202, and then clutch control in step 203, gear ratio control in step 204, throttle control in step 205, and line pressure control in step 206 are performed. It will be.

Clutch control (FIG. 5) First, in step 221, it is determined whether the operating lever 70, that is, the gearbox 3 is in the N range. If not in the N range, the process moves to step 222. In this step 222, it is determined whether the vehicle speed is high (for example, 10 km/h or more). If the vehicle speed is high, a vehicle speed flag is set in step 223, and then step 224
Move to.

In step 224, the differential value E' of the rotation speed E of the clutch input shaft 21 is determined, and it is determined whether or not the differential value E' is positive indicating an increase in the rotation speed. If so, the process moves to step 225. This step 2
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.
If it is tc, the process moves to step 226. Then, in step 226, the connection solenoid 36a of the clutch 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 225, E
If it is determined that it is not tc, the process moves to step 228, where the connection and disconnection solenoids 36a and 36b of the clutch solenoid valve 36 are both demagnetized to maintain the transmission torque of the clutch 2 as it is.

If it is determined in step 224 that E'>O is not true, the process moves to step 227, where it is determined whether Etc. When EtC, the process moves to step 226, clutch 2 is connected, and Et
If not c, the process moves to step 228 and the connected state of the clutch 2 is maintained as it is.

” The sequence of steps 224 to 225 is based on the premise that the rotation of the clutch input shaft 21 is increasing, and the flow from steps 225 to 226 is such that the rotation speed E of the clutch input shaft 21 is lower than the clutch output shaft 22. Since this is the case when the rotational speed C is higher than the rotation speed C, it is necessary to increase the transmission torque of the clutch 2, and therefore, the clutch 2 is connected in order to increase the transmission torque of the clutch 2. This case corresponds to, for example, a so-called half-clutch state when starting an automobile. The engagement speed of the clutch 2 at this time is increased as the rate of change E' of the engine speed is larger and as the vehicle speed is larger, and similarly, the degree of change of the gear ratio of the continuously variable transmission 4 to the upshift side is increased. The larger it is, the larger it will be. Further, the flow from step 225 to step 228 is when the transmission torque of the clutch 2 is exactly balanced, so the clutch 2 is held in the state 7B, which corresponds to a steady running state, for example. do.

Conversely, the flow from step 224 to 227 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 224 to 225. Since the flow is reversed, the determination in step 227 is changed to step 225.
In contrast to the determination in , it is checked whether E<C. Note that the flow from step 227 to step 226 corresponds to, for example, the case where the operation lever 70 is changed to the D range while driving with the control lever 70 set to the N range, and in this case as well, the so-called half-clutch state is reached. Form. Further, the flow from step 227 to step 228 corresponds to, for example, a deceleration traveling state using engine braking.

On the other hand, if it is determined that the vehicle is in the N range in step 221, the vehicle speed flag is reset in step 229, and then the process proceeds to step 230. This step 23
0 demagnetizes the connection solenoid 36a of the clutch solenoid valve 36. On the other hand, the disconnection solenoid 36
b is excited to disengage clutch 2. That is, in this case, it is clear that the driver himself requests a neutral state, so the clutch 2 is unconditionally disengaged.

In addition, when it is determined in step 222 that the vehicle speed is low, the process moves to step 231, where the accelerator pedal is pressed down.
It is determined whether or not 10 is turned ON by being stepped on. When this accelerator is not ON, the output of engine 1 is not requested, so the process moves to step 232.
It is determined whether the vehicle speed flag is set. When the vehicle speed flag is set, the vehicle speed has not yet decreased sufficiently, and in this case, the process moves to step 233, where it is determined whether or not the brake pedal 111 is depressed. be done.

Then, if the brake is ON, step 23
Move to 4, and here engine revolution e N E is 150
If it is determined that the speed is 0 rpm or less, the process proceeds to step 230 via step 229 (clutch 2 is disengaged).

Further, when it is determined in step 233 that the brake is not turned on, the process moves to step 235, and if it is determined here that the engine rotation speed NE is 1100 Orp or less, the process proceeds to step 230 via step 229. is performed (clutch 2 is disengaged). If it is determined in step 234 that the engine rotation speed NE is not less than 150 Orpm, and in step 235
If it is determined that the temperature is not less than 0 pm, step 2
The process moves to step 24 and the above-described processing is performed.

In this way, the engine rotation speed N is used as a criterion for determining whether or not to disengage the clutch 2 when the brake is turned on or off.
The reason why the magnitude of E is made different is to provide enough margin to avoid the danger of engine stalling, considering that the vehicle speed decreases faster when the brakes (ON) are applied than when the brakes are not applied. Note that when it is determined in step 232 that the vehicle speed flag is not set, the process of step 230 is performed via step 229 to prevent engine stalling (clutch 2 is disengaged).

Gear ratio and throttle control (Fig. 6) First, in step 241, the state of change in the accelerator opening α is determined. If the accelerator opening α is increasing, the gear change flag is set to 1 in step 242, and then step 243. In this step 243, the target acceleration GT is set from the amount of change Δα in the accelerator opening α. That is, as shown in FIG. 7, the larger the amount of increase in the accelerator opening is, the larger the acceleration desired by the driver is, and the target acceleration GT is set larger. After that, in step 244, the current vehicle speed V is set as the vehicle speed VT, and then the process moves to step 245.

In step 245, the running resistance F of the vehicle is determined depending on the gradient of the road surface on which the vehicle is running and the vehicle speed VT.
MW L. This running resistance Fl.

is the rolling resistance coefficient of the vehicle, γ, and the air resistance coefficient is g.
s, the front projected area is D, and the vehicle weight is W, then (gy
+ sinK) ・Calculation of W gs ・
It is obtained by adding the calculated value of D・VT2. To explain this point diagrammatically with reference to FIG. 8, at the constant running resistance line β'2 in the third quadrant of FIG.
This corresponds to finding the point x1 according to .

Then, in step 246, the target acceleration GT
The driving force Fe required to achieve this is calculated. This driving force Fe is obtained by adding the calculated value of GT·W to the running resistance FL. This means that in FIG. 8, on the constant running resistance line β' offset by GT-W in the running resistance FL, the constant power line γ of the engine 1 passes through the point x2 corresponding to the vehicle speed VT. This corresponds to finding the driving force at the time point X2.

After step 246, in steps 247 and 248, the engine operating characteristics to achieve the driving force Fe, the target engine speed NeT and the target throttle opening that achieve the most fuel efficiency to achieve the engine operating characteristics are determined. Tht is calculated. Both target values N
eT, T ht are the driving force F in FIG.
The intersection point x3 between the constant power line γ', which is obtained by mapping the constant power line γ corresponding to e to the first quadrant of FIG.
The engine speed corresponding to 3 is the target engine speed Ne
T, and the throttle opening corresponding to this intersection x3 is set as the target throttle opening Tht (step 248
).

Next, in step 249, it is determined whether the current engine speed NE is greater than the target engine speed NET, and if NE is greater than NET, the process proceeds to step 25.
After outputting the shift I/up signal at 0, NE or NE again
If not larger than T, a downshift signal is output in step 251, and then the process moves to step 252. Note that when the shift down signal is output in step 251, the larger the difference between the target acceleration GT and the current acceleration G, the faster the speed at which the gear ratio of the continuously variable transmission 4 is changed, that is, the gear ratio change speed d n / d. t is set to be large. The speed ratio change speed dn/dt can be adjusted by controlling the speed change solenoid valve 94 by duty, as shown in FIG. 9, for example.
As will be described later, since the line pressure changes, the duty ratio is set according to the line pressure supplied to the transmission solenoid valve 94 (in Fig. 9, the solid line and the broken line indicate two different line pressures). line pressure is higher than that shown by the dashed line or the solid line).

In step 252, the current throttle opening Th
is larger than the target throttle opening Tht, and if Th is larger than Tht, step 25
3, the throttle opening is decreased, and conversely, when Th is not greater than Tht, the throttle opening is increased.

If it is determined in step 241 that there is no change in the accelerator opening, the process moves to step 255, where the shift flag is determined. If it is determined that the shift flag is 1, the processing from step 243 described above will be performed.

The processing from step 255 to step 243 onwards is as follows:
As is clear from the explanation up to now, like the processes from step 242 to step 243 onward, the control is performed during constant acceleration operation.

On the other hand, when it is determined in step 241 that the accelerator opening degree has been decreased, the shift flag is sequentially set to O in step 256, and the vehicle speed flag in step 257 (the vehicle speed flag in FIG. 6 is the vehicle speed flag in FIG. 5). (different from the above) is set to O, then the process moves to step 258.

In this step 258, it is determined whether or not the position of the operating lever 70 is in the L range. If it is determined that the position is not in the L range, the process moves to step 259. In step 259, it is determined whether the vehicle speed flag is 1 or not.
9, the vehicle speed flag is 0. In this case, the current vehicle speed V is set to VT in step 260, the vehicle speed flag is set to 1 in step 261, and the target acceleration GT is set in step 262. is set to 0, and the processing from step 245 described above is performed. Then, on -day, after passing through step 261, the vehicle speed flag is determined to be 1 in step 259, so in this case, step 260.26
From step 262 to step 245 without going through step 1
Subsequent processing is performed. In this way, the route passing through step 262 is used as control during constant-speed driving to maintain the vehicle speed at the current vehicle speed.

In step 258, the operating lever 70 is in the L position.
If it is determined that the vehicle is in the range, this means that a large deceleration is required, so the process moves to step 263, where the gear ratio n is set so as to obtain a large deceleration according to the vehicle speed. be done. Thereafter, it is determined whether the actual gear ratio obtained by dividing the input shaft rotation speed Np of the continuously variable transmission 4 by the output shaft rotation Ns is larger than the gear ratio n set in step 263 above. And N p / N s >
When n, the throttle opening degree is decreased in step 267 after an upshift is performed in step 265, and after a downshift is performed in step 266 when Np/Ns>n is not satisfied. In this way, step 2
The route passing through 63 is used for control during engine braking operation.

Note that if the accelerator opening is held at the reduced position after once decreasing the accelerator opening, the process moves from step 241 to step 255, but in step 255, it is determined that the gear change flag is O. Therefore, the process moves to step 258 (because steps 241 to 256 have been passed in the previous control), and the above-described constant speed operation or engine brake operation is controlled.

Line pressure control (10th month) First, in step 271, the current gear ratio n is calculated from the input and output rotational speeds Np and Ns of the continuously variable transmission 4, and then in step 272, the fuel injection amount is calculated from the fuel injection pulse width. QF is calculated, and in step 273, the output torque Te of the engine 1 is calculated from the fuel injection amount QF. After this, in step 274, the reference line pressure PL is determined from the output torque Te of the engine 1 and the gear ratio n in step 271.
is calculated. Of course, this reference line pressure PL is based on the above (
Using equation 7), the minimum necessary size is determined to satisfy equation (3).

After this, in step 275, it is determined whether the clutch 2 is completely connected. Whether or not the clutch 2 is completely connected is determined, for example, by comparing the input and output shaft rotation speeds. When this clutch is fully connected, the process moves to step 276, and the reference line pressure PL is corrected between step 276 and step 281. This correction is performed at each step 27.
6 to 280 will be sequentially explained.

Step 276 When the absolute value of the target gear ratio change speed dn/dt (see explanation of step 251) is larger than the predetermined set value,
Since the V-belt 85 of the continuously variable transmission 4 is likely to slip, the reference line pressure PL is corrected in the direction of increasing it.

Step 277 is a correction based on the shift direction; when shifting up, the transmitted torque becomes smaller, so the line pressure is corrected to be smaller; when shifting down, on the other hand, the line pressure is corrected to be larger.

Step 278 This is a correction based on a change in the accelerator opening α (the same applies to changes in intake pressure), and when the absolute value of the rate of change dα/dt in the accelerator opening is larger than a predetermined set value, the line pressure is corrected in the direction of increasing it. . This correction is made in order to respond to changes in the output torque of the engine 1 with good response.

Step 277 is a correction during braking, and the brake pedal 143
When the pedal is depressed, the line pressure is corrected to increase. This is to cope with an increase in transmission torque corresponding to an increase in drive load due to the brake and release of inertia from the engine 1 due to a decrease in engine speed.

Step 280 Acceleration/Deceleration (Deceleration is treated as negative acceleration)
When the acceleration dv/dt is larger than a predetermined setting value, the line pressure is corrected in the direction of increasing it. In addition, during sudden braking when the brake pedal 143 is depressed greatly, that is, during sudden deceleration when dv/dt (in this case, a negative value) is smaller than a predetermined set value, the inertia of the engine 1 is released and the driving load is suddenly increased. In order to avoid impact on the V-belt 85 due to a sudden increase in transmission torque as the transmission torque increases, the line pressure is corrected in the direction of decreasing it. In other words, in this case, instead of increasing the transmission torque of the continuously variable transmission 4 in response to the increase in transmitted i/lux, priority is given to the durability of the V-belt 85, even if the V-belt 85 slips. Even reduce line pressure.

After the line pressure is corrected in steps 276 to 280 as described above, it is determined in step 281 whether or not the position of the operating lever 70 is in the neutral range, and if it is determined that the position is in the neutral range, the driving force is adjusted. Since transmission is not required, the line pressure is corrected to be lower. Then, in step 283, a current corresponding to the final line pressure after the various corrections described above is output to the relief valve 97. Also, step 2
If it is determined in step 81 that the range is not in the neutral range, the process proceeds to step 283 without passing through step 282.

Here, when it is determined in step 275 that the clutch is not fully engaged, step 284 is performed, and then the processing from step 276 onwards is performed. In this step 284, line pressure is supplemented based on the clutch control signal. To explain this point with reference to Fig. 11, (a) shows the change in accelerator opening, and (b) shows the engine output torque (calculated value), clutch transmission torque, and V-belt 85 ( (c) shows changes in the transmittable/achievable torque of the continuously variable transmission 4), and further, (c) shows changes in the engine rotation speed and the clutch output shaft rotation speed. In FIG. 11, from a stopped state, the clutch 2 starts to be connected at time t2, which is slightly later than the time t1 when the accelerator opening is increased, and the transmission torque of the clutch 2 is gradually increased. The clutch output shaft rotation speed also increases. Eventually, at time t3, the clutch transmission torque is once set to a constant value (maintained in a half-clutch state), and then at t4
At this point, the engine speed and the clutch output shaft speed match (the clutch 2 is substantially fully engaged). After this, the clutch transmission torque will further increase by the amount of the extra capacity. Then, when the accelerator opening degree starts to decrease at time tS, clutch 2 is disengaged at time t6, which is delayed from this, and at the time of clutch disengagement, the line pressure is corrected to become smaller, causing unnecessary The time the line pressure is kept high is shortened.

In the operating state described above, the transmission torque of the V-belt 85 continues until the clutch 2 is fully engaged (14
up to that point), that is, during the clutch engagement process, the clutch transmission torque is followed, and after this complete engagement of the clutch 2, the engine output torque is followed. When the clutch 2 is disengaged, the clutch transmission torque is made to follow the clutch transmission torque at time t7 when the transmission torque of the clutch 2 becomes smaller than the engine output torque. That is, in the clutch engagement process in which the engine drive system is controlled by the transmission torque of the clutch 2, the reference line pressure PL corresponding to the engine output torque in step 274 is adjusted so that the line pressure matches the required transmission torque of the V-belt 85. This prevents the V-belt 85 from slipping during the clutch connection process. In particular, if the transmission torque (line pressure) of the V-belt 85 during the clutch engagement process is adjusted based on the clutch control signal as in the embodiment, it is possible to prevent the slippage of the V-belt 85 while maintaining the line pressure. can be set as small as possible, and the oil pump 37 does not have to perform unnecessary work, although it is for a relatively short period of time, resulting in an improvement in fuel efficiency.

Although the embodiments have been described above, the present invention is not limited thereto, and includes, for example, the following cases.

■Each pulp 36.66.10 except for speed change solenoid 94
9, the pressure of the oil pump 37 may be supplied via a constant pressure valve. Especially for 109, which requires duty control, supplying constant pressure is -1 for facilitating the duty control. - is preferred.

(2) The throttle valve 9 may be driven by other driving means such as a step motor, or may be mechanically linked to the accelerator pedal 142 as in a normal vehicle.

■Correction to increase line pressure during clutch connection process is
It may be set to a constant value that always prevents the V-belt from slipping.

(Effects of the Invention) As is clear from the above description, the present invention prevents the V-belt of a continuously variable transmission from slipping even when the engine drive system is in the clutch engagement process controlled by the clutch transmission torque. Its durability can be increased.

Of course, in operating conditions where the engine drive system is dominated by the engine output torque, the reference line pressure is set in accordance with the engine operating condition, so unnecessarily large tension is applied to the V-belt. It is possible to prevent this from occurring, maintain its durability, and ensure improved fuel efficiency.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of the present invention. FIG. 2 is an overall schematic diagram showing an embodiment of the present invention. FIG. 3 is an overall system diagram showing one embodiment of the present invention. FIG. 4, FIG. 5, FIG. 6, and FIG. 10 are flowcharts showing an example of control according to the present invention. FIG. 7 is a diagram showing the relationship between target acceleration and the amount of change in accelerator opening. FIG. 8 is a diagram showing an example of obtaining the target engine speed and target throttle opening required to achieve the target acceleration. FIG. 9 is a diagram showing the relationship between the duty ratio and the target gear ratio change speed. FIG. 11 is a diagram showing how to set the transmission torque of the V-belt. FIG. 12 is a diagram illustrating the transmittable torque of the V-belt in relation to line pressure. l: Engine 2: Clutch 4: Continuously variable transmission 21: Clutch input shaft 22: Clutch output shaft 37: Oil pump 83: Drive pulley 84: Followed pulley 85: V-belt 88.91: Hydraulic actuator 97: Relief valve (line Pressure adjustment means) 131: Control unit 19-' end ° section■

Claims (1)

[Claims] (1) It is connected to the engine via a clutch, and includes a driving pulley, a driven pulley, and a V-belt wound around both pulleys, and the gear ratio is controlled by changing the groove spacing between the two pulleys using a hydraulic actuator. In the continuously variable transmission, the transmission includes: a clutch control means for controlling engagement and engagement of the clutch; a line pressure adjustment means for regulating line pressure supplied to the hydraulic actuator; a line pressure control means for controlling the line pressure adjustment means so that the line pressure is set to a high reference line pressure; 1. A line pressure control device for a continuously variable transmission, comprising: a line pressure correction means for adjusting the line pressure.