JPS6264639A - Control device of continuously variable transmission - Google Patents

Abstract

PURPOSE:To avoid a discontinuous acceleration and realize a smooth starting acceleration, by controlling to unify a synchromesh of a clutch and the starting of speed change except in case of a large opening of throttle. CONSTITUTION:A line pressure oil passage 21 at the injection side of an oil pump 20 links a secondary cylinder 10, a line pressure control valve 22, and a speed change control valve 23, and furthermore links from the speed change valve 23 to a primary cylinder 9. The line pressure oil passage 21 also links to a regulator valve 25, while an oil passage 26 links to solenoid valves 27, 28 and to one side of the control valve 23. The solenoid valves 27 and 28 are ON by a duty signal from a control unit 40 to exhaust the pressure, and OFF to output a regulator pressure PR. A pulse form control pressure from the solenoid valve 27 is balanced at an accumulator 30 to act the line pressure control valve 22.

Description

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

The present invention relates to a control device for a belt-type continuously variable transmission for a vehicle, and more particularly, the present invention relates to a control device for a belt-type continuously variable transmission for a vehicle, and more particularly, in a device that controls speed change using the speed of change of a gear ratio (shift speed) as a control counterpoint, a clutch that automatically connects and disconnects is used. This invention relates to shift start control in a transmission system that is combined with a step-change transmission. Regarding the speed change control of this type of continuously variable transmission, there is a basic hydraulic control system disclosed in, for example, Japanese Patent Laid-Open No. 55-65755. In this system, the gear ratio control valve operates in a balanced manner depending on the amount of accelerator depression and engine speed, and determines the gear ratio so that the engine speed is always constant. ing. Therefore, the shifting speed is mechanically determined by each gear ratio, primary pressure, etc., and the shifting speed cannot be directly controlled. For this reason, it has been pointed out that in transient conditions in the driving range, the gear ratio may cause hunting, overshoot, etc., resulting in deterioration of drivability. For this reason, in recent years, when controlling the speed change of a continuously variable transmission, there has been a tendency to electronically control the continuously variable transmission by taking into account the speed of change of the gear ratio. When considering a transmission system that includes a continuously variable transmission, the continuously variable transmission itself has a structure that does not have a neutral position like a manual transmission or an automatic transmission. Therefore, when the vehicle is stopped, it is necessary to disconnect the continuously variable transmission from the engine, and the disconnection means is to use a clutch that automatically engages, such as an electromagnetic clutch or a hydraulic clutch, or to disengage the continuously variable transmission from the engine. There is a method of providing a neutral position in forward switching '3Ailit. If the target is a continuously variable transmission that electronically controls the shifting speed as described above, combining it with an electromagnetic clutch has advantages such as integrating the control system into a common electronic control system for both. There is.

[Prior art 1] Therefore, conventionally, regarding the combination of the W1!1 type clutch and a continuously variable transmission, for example, Japanese Patent Application Laid-Open No. 57-9045
There is a prior art disclosed in Japanese Patent No. 0, which describes that a 74 magnetic clutch and a continuously variable transmission are controlled by an electronic control circuit, and a target speed ratio is determined to perform speed change control. [Problems to be Solved by the Invention] According to the above-mentioned prior art, the electromagnetic clutch and the continuously variable transmission are controlled separately. For this reason, when starting, the electromagnetic clutch is connected by the clutch current according to the engine speed, the vehicle speed, etc., whereas in the case of the "A" engine, the electromagnetic clutch is connected by signals such as the rotation speed of the primary and secondary brakes, the throttle opening, etc. When a gear shift is started, the synchronization point between the engine and primary pulley due to clutch connection and the shift start point may become different, resulting in discontinuous acceleration performance. As shown in Fig. 5 (2), in the control, the clutch torque, that is, the torque transmission force is applied as an increasing function of the engine speed, and it can be seen that the stall speed changes depending on the throttle opening. , the basics of shift control are as shown in Figure 5 (b), the gear is shifted at a higher engine speed than the lowest shift line,
The larger the throttle opening, the higher the speed changes. Therefore, start control when the electromagnetic clutch and the continuously variable transmission are controlled separately will be explained for each throttle opening. First, when starting with a small throttle angle as shown in FIG. 6(2), the engine speed is kept lower than the lowest shift line and synchronizes with the primary pulley at point P1, and then shifts start at point P2. In this case, there are two points: synchronization and shift start point.
This causes a rotational driving force change, resulting in discontinuous acceleration. Throttle g! In an example of 8 degrees, synchronization and shift start point P1. P2 matches, and smooth start is possible. In the case of the two throttle openings shown in Fig. 6(C), the engine speed suddenly increases and the shift start point P2 is already before the synchronization point P1 with the primary pulley speed, resulting in discontinuous acceleration. . In the case of starting with a large throttle opening as shown in FIG. It is desirable to eliminate the problem caused by separate synchronization points and shift start points, except in the case of The object of the present invention is to provide a sub-part device for a continuously variable transmission that prevents acceleration discontinuity during start and enables smooth start.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a continuously variable transmission combined with an electromagnetic clutch, in which the engine rotation speed and the primary pulley rotation speed are synchronized by the above-mentioned [4-type clutch] when starting at a predetermined throttle opening or less. At that point, gear shifting will begin. If the engine speed is below the minimum shift line at the time of synchronization, the target gear ratio is corrected to a smaller value as an increasing function of the difference between the two, and the shift is started. (Function) Based on the above configuration, unless the synchronization of the large throttle opening and the timing of the shift start are mechanically inconsistent, the gear shift occurs when the primary pulley rotation speed is synchronized with the engine rotation speed due to the connection of the electromagnetic clutch. Since the synchronization and shift start always match, it is possible to perform smooth starting acceleration.In addition, if the engine speed at the time of synchronization is lower than the minimum shift-in, the target gear ratio By setting the speed change ratio to be smaller than the maximum speed change ratio and starting the speed change, a smooth transition to the lowest speed change line occurs after the same WI, and it is possible to avoid acceleration discontinuity in this case as well.

【Example】

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, an outline of a transmission system including a continuously variable transmission to which the present invention is applied will be explained. An engine 1 is connected to a main shaft 5 of a continuously variable transmission 4 via an electromagnetic clutch 29 and a forward/reverse switching device 3. do. The continuously variable transmission 4 has a subshaft 6 arranged parallel to the main shaft 5, and a primary pulley 7 on the main shaft 5.
A secondary pulley 8 is provided on the subshaft 6, and each pulley γ
, 8 are equipped with hydraulic cylinders 9, 10 on their movable sides, and have a drive belt 11 wrapped around them. Here, the pressure receiving area of the primary cylinder 9 is set larger,
Due to the primary pressure, the pulley 7.8 of the drive belt 11
The winding speed is continuously variable by changing the diameter ratio. Further, the subshaft 6 is connected to an output shaft 13 via a set of glue reduction gears 12, and the output shaft 13 is connected to a final gear 14.
．． The transmission is configured to be transmitted to drive wheels 16 via a differential gear 15. Next, the oil pressure of the continuously variable transmission 4 is 1! To explain the III system, an oil pump 20 driven by the engine 1
and a line pressure oil passage 21 on the discharge side of the oil pump 20.
However, the secondary cylinder 10. Line pressure control valve 22. The gear speed change control valve 2 communicates with the gear change speed control valve 23.
3 to the primary cylinder 9 via an oil passage 24. The line pressure oil passage 21 further communicates with a regulator valve 25, from which a constant regulator pressure oil passage 26 communicates with a solenoid valve 27, 28 and one of the transmission speed control valves 23. Each solenoid valve 27.28
is 11. Depending on the duty signal from the lJ m unit 40, for example, A is turned on to exhaust pressure, and it is turned off to reduce the regulator pressure P.
It outputs R, and generates such a pulse-like control pressure. The pulsed control pressure from the solenoid valve 27 is averaged by the accumulator 30 and acts on the line pressure control valve 22. On the other hand, the pulse-like control pressure from the solenoid valve 28 remains at the speed change speed υItll.
It acts on the other side of the valve 23. In the figure, reference numeral 29 is a drain oil passage, 31 is an oil pan, and 32 is an orifice. The line pressure control valve 22 performs 1IIA1111 of the line pressure PL using the averaged control pressure from the solenoid valve 2γ. The gear change speed control valve 23 has a refueling position connecting the line pressure oil passage 21.24 and a line pressure oil passage 24 depending on the relationship between the regulator pressure and the pulse-like control pressure from the solenoid valve 28.
Operates at the oil drain position to drain the oil. Then, the operating state of the two positions is changed depending on the duty ratio, and the oil supply to the primary cylinder 9 or the Jπ oil flow ff1 is changed.
Q is controlled, and the speed change is controlled by the speed change speed di/dt. Referring to FIG. 2, the electrical control system will be explained. First, the speed change control system will be explained. The primary pulley 7, the secondary pulley 8. It has respective rotational speed sensors Ill, 42, 43 of the engine 1, and a throttle opening sensor 44. Then, in the tilt m unit 40, the rotation signals Np and Ns from both pulley rotation speed sensors 41 and 42 are inputted to the actual gear ratio calculation unit 45 and calculated as
+)/NS to determine the actual gear ratio i. In addition, a signal N from the secondary pulley rotation speed sensor 42
S and the signal θ of the throttle opening sensor 44 are input to the target gear ratio search unit 4G, where the signal θ is determined based on the gear shift pattern.
The target gear ratio is is searched from the -θ daple. The signal θ of the throttle II 1 degree sensor 44 is detected by the acceleration detection section 5
1, the throttle opening change θ is calculated from dθ/dt, and based on this, the coefficient k is set as a function of θ in the coefficient setting section 47. Actual gear ratio 1 of actual gear ratio calculation unit 45
．． Target gear ratio search tIJ4B steady state target gear ratio is
The coefficients of the coefficient setting section 47 include the shift speed calculation section 48.
is input, and the shift speed fli/dt is calculated by di/dt=k (is −t), and if the sign is positive, the shift is down, and if the sign is negative, the shift is up. Reliance of the gear change speed calculation unit 48 and the actual gear ratio calculation unit 45 @d1/
dt, + are further input to the duty ratio search section 49. Here, the duty ratio D −f(di/dt, i
) A table of shiyu/dt and i is set by the clerk, and in the table of -di/dt and i for upshift, the duty ratio is set to a value of, for example, 50% or more, and di/dt for downshift is set. In the table with and 1, the duty ratio is distributed to values below 50%.

[No. In the shift-up table, the duty ratio is set as a decreasing function for i and as an increasing function for -di/dt, and in the shift-down table, the duty ratio is set as an increasing function for i. A decreasing function is set for di/dt. Therefore, the duty ratio is searched using such a table. The duty ratio signal 9 from the duty ratio search section 49 is input to the solenoid valve 28 via the drive section 50. Next, to explain the line pressure control system, the signal 6.1222 of the throttle opening sensor 44 and the rotation speed sensor 43
The signal Ne of θ is input to the engine torque calculation unit 52, and θ
Find the engine torque T from the -Ne table. On the other hand, based on the actual gear ratio i from the actual gear ratio calculation unit 45, the required line pressure setting unit 53 calculates the required line pressure PLU per intermediate torque, and this and the engine torque lower value of the engine torque calculation unit 52 are determined. The target line pressure PL is inputted to the target line pressure calculation unit 54 and calculated by PL-PLIJ-T. The output PL of the target line pressure calculation section 54 is input to a duty ratio setting section 55 to set a duty ratio corresponding to the target line pressure PL. A signal corresponding to this duty ratio is input to the solenoid valve 27 via the drive section 56. On the other hand, the above control system includes a throttle degree determination section 60 to which a throttle opening degree signal .theta. is input as a speed change start control at the time of starting, and determines whether the throttle degree is less than or equal to a predetermined throttle ON degree .theta.1. In addition, the engine and primary booster rotational speed signals Nc <Np are input to the same II determination section 61,
Outputs a synchronization signal when Ne −No = O, and outputs a signal N
e is further input to the engine speed determination section 62, and it is determined that Ne>N for the engine speed N sin of the lowest shift line.
1n or Ne<N 1n is determined. Then, the output signals of each of the determination sections 60 to 62 are input to the shift start section 63, and θ<θ1, Ne −Np 0. Ne >
N5in (7) If the condition is satisfied, a shift start signal is output and the target gear ratio is from the target gear ratio search unit 46.
Move from maximum state to table search. Also, at the shift start portion, θ1. Ne−Np=
For the condition of Q, Ne < Ni1n, f, t R large (7)
While outputting the target gear ratio is, the correction amount calculation unit 64 calculates the correction amount β as an increasing function of the difference between N 1n and Ne as follows. β=α(Niin −Ne) Then, in the target speed ratio correction unit 65 added to the output side of the target speed ratio search unit 46, a correction of 1 s (1−β) is performed. Next, the operation of the continuously variable transmission control device configured as described above will be explained. First, the power from the engine 1 in response to the depression of the accelerator is transferred to the clutch 2. It is input to the primary pulley 7 of the continuously variable transmission 4 via the switching device 3, and the drive belt 11. The power that has been shifted by the secondary pulley 8 is output, and this is transmitted to the drive wheels 16 to drive the vehicle. During the above-mentioned driving, the target line pressure is set to be larger as the engine torque T is larger in the lower speed gear where the value of the actual gear ratio i is larger, and a signal with a corresponding larger duty ratio is input to the solenoid valve 27 to control the control pressure. By generating a small amount of pressure and operating the line pressure control valve 22 with the averaged pressure, the line pressure PL of the line pressure oil passage 21 is increased. As the gear ratio i becomes smaller and the engine torque also becomes smaller, the duty ratio is reduced and the control pressure is increased, so that the line pressure PL is controlled to decrease as the drain amount increases. A force corresponding to the torque transmitted by the belt 11 is applied to the pulley pusher 41. The line pressure PL is always supplied to the secondary cylinder 10, and the speed change speed is controlled by supplying and discharging oil to the primary cylinder 9 using the speed change control valve 23. This will be explained below. First, the signal Np from each sensor 41, 42 and 44. Ns and θ are read, the actual speed change ratio i is determined by the speed change calculation section 45 of the control unit 40, the target speed change ratio is is determined by the target speed change ratio search section 46, and using these and the coefficient K, the speed change speed calculation section 48 calculates the actual speed change ratio i. Find the shift speed di/dt. So is<
For an upshift having a relationship of t and a downshift having a relationship of is>i, the duty ratio is searched by the duty ratio search unit 49 using a table based on ±di/dt and i. The duty signal is input to the solenoid valve 28 to generate a pulse-like control pressure, which causes the speed change speed control valve 28 to generate a pulse-like control pressure.
Repeat step 3 at two positions: oil supply and oil drain. Here, in the upshift, when the duty ratio is 50% or more, the pulse-like control pressure by the solenoid valve 28 is such that the zero pressure time when it is on is longer than the regulation rake pressure PR time when it is off, and the shift speed control valve 23 The operating time at the refueling position is long (as a result, the briny cylinder 9 is refilled with more oil than the oil drained, causing an upshift effect.And if -di/dt is small on the low gear side where i is large, the value of D Since the amount of oil is small, the amount of oil supplied is small and the speed of the shift is slow. However, as the gear shifts to a high speed gear with a small i and -di/dt becomes large, the value of D increases, the amount of oil supplied increases, and the speed of the shift becomes faster. On the other hand, in a downshift, the duty ratio is less than 50%, so the control pressure is opposite to that described above, and the shift speed control valve 23 operates for a long time at the oil draining position, causing the briny cylinder 9 to It acts more as oil drain than oil supply.In this case, in the low speed gear where i is large, d i
/ d When t is small, the value of D is large, so the amount of oil discharged is small and the gear shift speed is slow, shifting to a high speed gear with a small i, and as di/dt becomes large, the value of D becomes small. The amount of oil drained increases and the gear shifting speed becomes faster. In this way, the gears are shifted steplessly by shifting up or down while changing the shift speed in the entire range between the low gear and the high gear. On the other hand, control in the case of starting will be explained using the flowchart of FIG. First, when the accelerator is depressed, the throttle opening becomes a certain degree and the engine speed increases, and as a result, the electromagnetic clutch 2 becomes connected with the clutch characteristics shown in the fifth timing. Therefore, based on the increase in clutch torque, the engine power is changed to continuously variable speed I! ! 4, the speed is decelerated at the maximum gear ratio, and the transmission is transmitted to the drive wheels 16, thereby starting the vehicle. Here, if the throttle angle is large, the regulation of the target gear ratio search unit 46 is canceled from the beginning by the output signal of the throttle opening determination unit 60, and 1! Shifting by the magnetic clutch 2 starts after the same day. On the other hand, when θ is smaller than θ1, the electromagnetic clutch 2 is in a half-clutch state, and under the condition of Ne-N1)≠0, the synchronization determination unit 61 does not output a synchronization signal.
3, the target speed ratio IS of the target speed ratio search section 46 is fixed at the maximum. Then, when the engine and primary pulley rotational speeds Ne and NO are synchronized, the electromagnetic clutch 2 is connected, the restriction of the target gear ratio search unit 46 is released, and the target gear ratio IS based on the table search is output and the gear shift starts. I will do it. Therefore, as shown in FIG. 4(2), no matter how the engine speed rises due to the degree of accelerator depression, the same point P1 always coincides with the shift start point P1. On the other hand, at this time, if the engine speed at the time of synchronization is equal to or lower than the minimum shift speed N sin, the target speed ratio correction section G5
Since the target gear ratio is is corrected to s (1-β) and set smaller than the maximum, as shown in ) in FIG.
After I, start shifting smoothly toward the lowest shift line. Here, the correction amount β is determined by an increasing function of Ni1n - Ne, so as shown in the figure, the larger the difference, the greater the shift amount, and the shift will always be on the lowest shift line in any case. Although one embodiment of the present invention has been described above, the present invention is not limited to combination with an electromagnetic clutch. It can also be applied to anything that is electronically controlled for speed change. [Effects of the Invention] As described above, according to the present invention, in a transmission system in which a continuously variable transmission is combined with a clutch that automatically engages, when the throttle opening is large, which is impossible at the time of starting, except,
Since the synchronization by the clutch and the shift start are controlled to coincide, discontinuous acceleration is eliminated and smooth start-up acceleration is achieved. If the engine speed during synchronization is less than the minimum shift speed, the shift control is performed to shift to the lowest shift line.
In this case as well, discontinuous acceleration does not occur and the effect is great.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the control device of the present invention, and FIG.
The figure is a block diagram of the electric control system, Figure 3 is a flowchart explaining the action, Figure 4 is a characteristic diagram according to the present invention (Q, ) in the figure is a speed change characteristic diagram, and 6th figure or Φ is a conventional characteristic diagram. 1... Engine, 2... Electromagnetic clutch, 4...
Continuously variable transmission, 40... Control unit, 46... Target gear ratio search unit, GO... Throttle opening determination unit, 61
...Synchronization determination unit, 62...Engine rotation speed determination unit,
63... Shift start section, 64... Correction amount calculation section, 65
...Target gear ratio correction section. Patent Applicant Fuji Heavy Industries Co., Ltd. Agent Patent Attorney Nobuko Kobashi Ukiyo Patent Attorney Susumu Murai 4-Figure Time Figure 3 Figure 6 (C) Figure between U9 (b) Between trains

Claims (2)

[Claims] (1) In a continuously variable transmission combined with an electromagnetic clutch, a continuously variable transmission that starts shifting when the engine speed and primary pulley rotation speed are synchronized by the electromagnetic clutch when starting with a predetermined throttle opening or less. Machine control device. (2) If the engine speed is below the minimum shift line at the time of synchronization, the target gear ratio is corrected to a smaller value as an increasing function of the difference between the two, and the shift is started.
A control device for a continuously variable transmission as described in 2.