JPS624646A - Control device of continuously variable speed change gear - Google Patents

Abstract

PURPOSE:To satisfy response and maneuverability with a simple structure, and moreover, to exercise the engine brake effectively on a down slope, while securing the following performance on a plain road, by setting an object speed change rate as a control object, and controlling the speed change rate directly by a single control valve. CONSTITUTION:Signals from sensors 41, 42, and 44 are read, and the real speed change ratio (i), the object sped change ratio (is), and then, di/dt are determined in computers and detectors in a control unit 40. When running on a down slope, the di/dt is determined depending on the variation between the larger value of the corrected speed change ratio (ialpha) and the object speed change ratio (is), and the real speed change ratio (i), and then, the duty ratio is found from the said di/dt and the speed change ratio (i). Depending on the amount of the duty ratio and the amount of the conversion, a speed change control valve is activated through a solenoid valve 28, the input and output of the control oil and the rate of the flow conversion from the secondary cylinder to the primary cylinder are controlled, and the gear shift and the speed change rate are converted. As a result, the effect of the engine brake becomes more effective on a down slope, by using the corrected speed change ratio for shift down.

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, to a control device for controlling a speed change of a gear ratio with Mm as a target, and for changing a speed change characteristic when descending a slope.

[Background of invention]

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 Application Laid-Open No. 55-65755. This is the amount of accelerator depression and 172
．． The gear ratio control valve operates in a balanced manner based on two rotational speed factors, and determines the gear ratio so that the engine rotational speed is always constant, and the gear ratio is controlled. Therefore, the shifting speed is mechanically determined by each gear ratio, primary pressure, etc., and the shifting speed can be directly determined by ill'
I couldn't do IB. Therefore, it has been pointed out that in a transient state of the driving range, the gear ratio may cause hunting, overshoot, etc., which deteriorates drivability. For this reason, in recent years, when controlling continuously variable transmissions, there has been a tendency to electronically control the speed change of the gear ratio.

[Conventional Technique #i2] Conventionally, regarding the above-mentioned continuously variable transmission that takes into account the speed change speed, for example, Japanese Patent Laid-Open No. 59-159
There is a prior art in Publication No. 456. This has a gear ratio changing directional switching valve device and a gear ratio changing speed control valve device for speed change control, and when the changing direction switching valve device is switched to either oil supply or oil drain, the changing speed control valve device uses an electromagnetic The valve operates the spool valve at a specified duty ratio to control the speed of change of the gear ratio. In addition, regarding a device that sets the gear shift speed and changes it during engine braking, for example, Japanese Patent Application Laid-Open No. 59-2082
There is a prior art disclosed in Japanese Patent Application No. 54, in which the gear change speed is set as a decreasing function of the vehicle speed during deceleration, and the engine brake is applied weakly at high speeds and strongly at low speeds. [Problems to be Solved by the Invention] According to the former of the above-mentioned prior art, two types of valve devices are used for speed change control, so the structure is inevitably complicated. In addition, the latter of the prior art is advantageous in improving coasting performance when coasting on a flat road;
There is a problem with the effectiveness of the engine brake when coasting downhill. In other words, when the vehicle is coasting with the axle open and the vehicle speed is relatively high, the continuously variable transmission is shifted to a high gear, such as overdrive, and when going downhill, this state continues and the engine brake is not effective. . Therefore, at this time, if the shifting speed is set as in the prior art described above, the effectiveness of the engine brake becomes even more insufficient. Therefore, it is conceivable to conversely increase the shift speed at high speeds, but the state in which engine braking is less effective continues until relatively low speeds, and it is hardly expected that engine braking will reduce the vehicle speed during that time. Therefore, even if an attempt is made to control the effectiveness of engine braking by determining the shift speed in relation to the vehicle speed, it cannot be effectively achieved under conditions such as downhill. The present invention has been made in view of these points, and by determining a target shift speed and directly controlling the shift speed using that as a control target, it satisfies both responsiveness and drivability, and further improves smoothness. The purpose of the present invention is to provide a control device for a continuously variable transmission that prevents engine braking from effectively working when descending a slope while ensuring coasting performance on the road.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a speed change speed di, /
dt is expressed as a numerical value of the flow rate Q, and the flow rate Q is the primary pressure P.
P, line pressure PL, and shift speed are functions of the duty ratio when the control valve is operated in two positions, oil supply and oil drain.Since each pressure Pp and PL are functions of the gear ratio 1, etc., the shift speed is di/dt is a function of the duty ratio and the gear ratio i. Further, the gear change speed di/dt is determined based on the deviation between the target gear ratio is and the actual gear ratio i in steady state. For this reason, a variable speed control valve is provided that operates in two positions, oil supply and oil drain, depending on the on/off state of the duty signal. Then, a corrected gear ratio iα is determined according to the inclination angle on a downhill slope along with the target gear ratio IS for steady running, and the gear ratio f9K d i / d is determined based on the deviation between the larger one and the actual gear ratio i.
t is determined, and the duty ratio is determined based on this and the gear ratio i, and the gear speed control valve is operated.

[For production]

After discovering the above configuration, a target speed change speed is determined, and the speed change speed is controlled using that as a control target. On a flat road with an inclination angle of zero, the target gear ratio IS is selected, but when going downhill, the corrected gear ratio iα is selected and the gear change characteristics are changed to uniformly downshift. This means that the gears will be shifted slowly, thus making it possible to effectively apply engine braking.

【Example】

Embodiments of the present invention will be described below based on the drawings. Referring to FIG. 1, an outline of a transmission system including a continuously variable transmission to which the present invention is applied will be described. An engine 1 is connected to a main shaft 5 of a continuously variable transmission 114 via a clutch 21 and a forward/reverse switching device 3. Continuously variable speed 8!4 has subshaft 6 relative to main shaft 5.
are arranged in parallel, a primary pulley 7 is provided on the main shaft 5, a secondary pulley 8 is provided on the sub@6, and each pulley 7.
8 is equipped with a hydraulic cylinder 9.10 on the movable side, and a drive belt 11 is attached to it. Here, the primary cylinder 9 is set to have a larger pressure receiving area, and due to the primary pressure, the winding of the drive belt 11 around the pulleys 7.8 changes the ratio of diameters so that the speed is continuously variable. 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, to explain the hydraulic control diameter of the continuously variable transmission 4, it has 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 is connected to the secondary cylinder 10. Line pressure control valve 22. The transmission speed control valve 23 communicates with the transmission speed control valve 23 , and the transmission speed control valve 23 communicates with the primary cylinder 9 via a line pressure oil passage 24 . The line pressure oil passage 21 further communicates with the regulator valve 25, and the oil passage 2 with constant regulator pressure from the regulator valve 25.
G is the solenoid valves 27 and 28 and the speed change control valve 2
Connects to one side of 3. Each solenoid valve 27, 28 is turned on, for example, to exhaust pressure, and turned off, in response to a duty signal from the control unit 40, and outputs the regulator pressure PR, and generates such a pulse-like control pressure. The pulsed control pressure from the solenoid valve 27 is averaged by the accumulator 30 and applied to the line pressure control valve 22. On the other hand, the pulse-like control pressure from the solenoid valve 28 acts directly on the other shift speed control valve 23. J5, code 2 in the diagram
9 is a drain oil passage, 31 is an oil pan, and 32 is an orifice. The line pressure control valve 22 controls the line pressure PL based on the gear ratio i and the engine torque T using the averaged control pressure from the solenoid valve 27. The shift speed control valve 23 has an oil supply position where it connects the line pressure oil passages 21 and 24 and an oil drain position where it drains the line pressure oil passage 24, depending on the relationship between the regulator pressure and the pulsed υ1111 pressure from the solenoid valve 28. works. Then, the operating state of the two positions is changed by the duty ratio to control the oil supply or drain oil flow mQ to the primary cylinder 9, and the speed change ratio i is changed, and the speed of change d i
/ d t can also be changed. That is, the required oil amount ■ of the primary cylinder 9 is determined by the gear ratio i
It is determined mechanically and structurally in relation to V=r (
i) Become, flow! Since IQ is the differentiation of oil ff1V with respect to time, Q = clv/clt - (df (i > /di)
(old/dt), and the flow rate Q and the gear change speed di/dt correspond to each other using the gear ratio i as a parameter. Therefore, the following formula is obtained. di/dt=f(Q,i) Also, primary cylinder internal pressure Pp, line pressure PL, flow coefficient C1 power acceleration9. Oilified iumγ. Valve refueling boat opening area Si, oil draining boat opening area So
In other words, the oil supply flow rate Qt and the oil discharge flow rate Qo are Qo =
c-8o [(2(JPI) )/y]4-a-8o
(Pp) Self Qi = a-8i (PL -pp)! [a=c
(2g/γ) order] It can be expressed as: Therefore, if the duty ratio (on/off ratio) is D, then
The average flow ff1Q for one cycle (assuming oil supply is positive) is: Q=a (D-8i (PL-pp) - (1-D
>XSo·(Pp), and if a, Si−, and So are constants, the following equation is obtained. Q= f(D, PL, PEI) Here, the line PL is controlled by the gear ratio i and the engine torque T, and the primary cylinder internal pressure Pp is determined by the gear ratio i and the line pressure PL, so Assuming that is constant, Q=f(D,i), and the following equation holds true. (2)/dt=f(D, i) Therefore, when the formula is expanded, it becomes Q-r(di/dt, i), and from the above, it can be seen that the shift speed di/dt corresponds to the duty ratio. And the duty ratio is
It is determined by the relationship between the speed change speed di, /dt and the speed change ratio i. On the other hand, the shift speed di/dt is the target shift ratio is
Since it is based on the deviation between the actual speed ratio i and the actual gear ratio i, the following equation holds true. di/dt=k (is −i) From this, at each gear ratio i, the gear shift speed d can be calculated from the above equation.
If i/dt is determined, the duty ratio can be found based on it, and if the gear speed control valve 23 is operated based on this duty ratio, the gear ratio change speed control is performed over the entire range of gear shifting between the low gear and the high gear. becomes possible. 1s-i in the above equation corresponds to the change ΔTe in the engine torque, and the coefficient can be considered to represent the driver's intention to accelerate. Therefore, by making the coefficient k variable according to changes in engine load, it is possible to determine the shift speed di/dt during acceleration as well as during steady state. Furthermore, transient states and various operating states other than steady state and acceleration can be dealt with by correcting the determined speed change speed and target gear ratio based on the steady state. Therefore, the electrical control system shown in FIG. 2 is constructed based on the above-mentioned principle, and will be explained below. First, to explain the variable speed control valve, the primary pulley 7, secondary pulley 8. It has each rotation speed sensor 41, 42, 43 of the engine 1, and a throttle opening sensor 44. Then, in the control unit, the rotation signals Np and Ns from the two boolean rotation speed sensors 41 and 42 are input to the actual gear ratio calculating section 45, and the actual gear ratio i is determined by i=Np/Ns. In addition, the signal NS from the secondary pulley rotation speed sensor 42 and the throttle opening sensor 44
The signal θ is input to the target gear ratio search section 46. Here, based on the shift pattern not shown in Figure 3 (F), Figure 3 Φ)
The table shown in is set up, and the NS of this chiful
, is is searched from the values of θ. - The signal θ of the throttle IF 11 degree sensor 44 is
1, the throttle opening change θ is calculated from dθ/dt, and based on this, the coefficient setting section 47 sets the coefficient K as a function of θ. Then, the actual gear ratio i of the actual gear ratio calculation unit 45
, target gear ratio 1sJ5 in steady state of target gear ratio search group 46
and the coefficient of the coefficient setting section 47 is input to the shifting speed calculating section 48, and the shifting speed di/dt is determined by di/dt=k (is - i), and its positive value is determined. The negative sign determines upshift or downshift. Next, as a correction when descending a slope, the inclination angle α of the vehicle body when descending a slope is
The signal α from the tilt angle sensor 52 and the signal Ns from the secondary pulley rotation speed sensor 42 are input to a correction gear ratio calculation unit 53, and the correction gear ratio iα is calculated as shown in FIG. 0 as an increasing relationship of the inclination angle α. Then, the target gear ratio search unit 46 and the corrected gear ratio calculation unit 53 input to the gear change characteristic change determination unit 54, and if is>tα when traveling on a flat road, is is selected, and when traveling downhill, is<iα In this case, select iα. In this way, is or iα from the shift characteristic change determination section 54 is input to the shift speed calculation section 48, and when going downhill, the shift speed is determined as dt/dt = k < iα-1).
Calculated by Furthermore, the signal d i / d from the shift speed calculation unit 48
t and the signal i from the actual gear ratio calculation section 45 are input to the duty ratio search section 49. As already mentioned here, due to the relationship of duty ratio D=f(di/dt, i), a table of duty ratios based on d i /(lt, i) is set as shown in FIG. 3(C). The duty ratio is searched from this table. In this table, the gear ratio i becomes smaller and shifts to a high speed gear,
As the shift speed di/dt becomes smaller, the duty ratio of one shift is set smaller. And the above duty ratio search? ! A signal having a duty ratio of 149 is input to the solenoid valve 28 via the drive unit 50. Next, the line pressure control system will be explained. The signal θ of the throttle opening sensor 44, the engine rotation speed sensor 43
The signal Ne of
The target line pressure PL is determined by the elements. Then, the duty ratio setting section 56 determines a duty ratio corresponding to the target line pressure PL, and this duty signal is inputted to the solenoid valve 27 via the driving section 57. 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 cantilever pulley 8 is output, and this is transmitted to the drive wheels 16 to drive the vehicle. During the above-mentioned running, 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 1 is larger, and a corresponding duty signal is input to the solenoid valve 27 to generate the control pressure. By operating the line pressure control valve 22 using 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 line pressure PL is controlled to be reduced by the same action, and in this way, the pressure corresponding to the torque transmitted by the drive belt 11 is always reduced. Pushing exerts force. The line pressure PL is always supplied to the secondary cylinder 10, and the speed change speed is controlled by supplying oil to the primary cylinder 9 by the speed change control valve 23, which will be explained below. First, the signals 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 IIIIIIIII unit 4o, the target speed change ratio is is determined by the target speed change ratio search section 46, and the speed change speed sieving section 48 uses these and the coefficient k. Find the shift speed di/clt. Therefore, in the upshift related to ISgu1, di/
dt becomes a negative value. Therefore, the duty ratio search unit 49
The duty ratio is searched based on di/dt and i. The above-mentioned duty signal is input to the lenoid valve 28 to generate a pulse-like control pressure, which causes the speed change control valve 23 to repeatedly operate in two positions, oil supply and oil drain.Here, when the duty ratio becomes smaller, , due to the off time, the shift speed control valve 23 has a good operating time in the refueling position (so that the primary cylinder 9 is refueled, and thus shifts up.On the other hand, when the duty ratio becomes large, the on time The operation time in the low oil position becomes longer, and the fry cylinder 9 is drained of oil, which causes a downshift.In this case, the gear ratio of the gear ratio old/dt
corresponds to a change in the duty ratio, so if the deviation between the target gear ratio is and the actual gear ratio i is small, the change in the duty ratio is small and the 8! of the primary cylinder 9! Due to the small amount of change, the gear shifting speed becomes slow. On the other hand, as the deviation between the target gear ratio is and the actual gear ratio i increases (as the difference in the duty ratio increases, the flow rate change in the primary cylinder 9 increases, and the gear shift speed becomes faster. In this case, the speed is changed steplessly by upshifting or downshifting while changing the speed ratio change speed.On the other hand, when accelerating in the steady operation, the acceleration detecting section 51T
: The acceleration state is detected by the change θ in the accelerator opening, and the coefficient k is set accordingly. Therefore, in the case of sudden acceleration, the shift speed di/dt becomes a large value, prompting downshifting at a fast shift speed and acceleration 1#. On the other hand, during engine braking when the accelerator is released, [
The target speed ratio is is set to the minimum speed ratio, for example, 0.5 in the type 1 speed ratio search unit 46, but on a flat road with a zero slope angle, the corrected speed ratio iα of the correction speed ratio calculation unit 53 is iα<0. 5
By setting to
s appears. This allows this i
The speed change is controlled using s, and coasting performance is maximized by is=0.5. On the other hand, when going downhill, the correction gear ratio calculation unit 53 calculates iα as α
Since iα>0.5 is set in relation to is, the shift characteristic change determination unit 54 outputs iα instead of is. Therefore, the shifting speed is di/dt=k(iα
-1), the shift characteristic is changed to one that uniformly shifts to the lower gear side, and the shift is downshifted by 1s-iα, and the engine brake is applied accordingly. As the inclination angle α becomes larger, the correction gear ratio iα is set to a larger value and the gear ratio is further downshifted to the lower gear side, thereby increasing the effectiveness of the engine brake. Although one embodiment of the present invention has been described above, it is not limited to the above embodiment.

【Effect of the invention】

As described above, according to the present invention, since the hydraulic control system is configured to control the speed change using a single speed change control valve, the structure is simplified and the control is easy. This method directly controls the speed change speed by making the speed change ratio correspond to the duty ratio of the solenoid valve and determining the duty ratio based on the deviation between the target speed ratio and the actual speed ratio.
Good in terms of responsiveness etc. During engine braking on a flat road, the target gear ratio is set in the direction of the minimum gear ratio depending on the accelerator opening, etc., and therefore the coasting performance is good. On the other hand, when going downhill, the gear ratio corrected based on the inclination angle is used to downshift, which makes it possible to effectively apply engine braking and prevent brake fade on long downhill slopes. It never goes away.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the hydraulic control system in an embodiment of the T1II device of the present invention, FIG. 2 is a block diagram showing the T1 control system, FIG. 3 is a characteristic diagram and a diagram showing a table, and FIG. The figure is a flowchart showing the action of speed change control. 4... Continuously variable transmission, 7... Primary pulley, 8...
...Secondary pulley, 9...Primary cylinder,
DESCRIPTION OF SYMBOLS 10... Secondary cylinder, 11... Drive belt, 21.24... Line pressure oil path, 23... Shift speed control valve, 28... Solenoid valve, 4o... Control unit, 45... ...Actual gear ratio calculation unit, 46...Target gear ratio search unit, 47...Coefficient setting unit, 48...Shift speed calculation unit, 49...Duty ratio search unit, 52...Inclination angle廿器, 53...Correction gear ratio calculation unit, 54...
Shift characteristic change determination section. Patent applicant: Fuji Heavy Industries Co., Ltd. Agent: Patent attorney: Shin Kobashi Slag quantity: Patent attorney: Susumu Murai, ? 3
u Ns Ns(d) Buddha(C)

Claims (1)

[Scope of Claims] A variable speed control valve is provided in the middle of the line pressure oil path to the primary cylinder and operates in two positions, oil supply and oil drain, depending on the on/off of a duty signal, and the control valve operates in two positions, oil supply and oil drain, depending on the relationship between accelerator opening and vehicle speed. For the target gear ratio during steady driving, a corrected gear ratio is calculated based on the relationship between the inclination angle and vehicle speed when going downhill, the larger of these gear ratios is selected, and the gear change speed is determined based on the deviation between it and the actual gear ratio. A control device for a continuously variable transmission that determines a shift speed and sets a duty ratio of the shift speed control valve in accordance with the shift speed.