JPH023736A - Controller for vehicle equipped with continuously variable transmission - Google Patents

Abstract

PURPOSE:To secure the reliability of a belt by reducing the input torque itself or the speed change ratio when the input torque supplied into a continuously variable transmission exceeds an allowable transmission torque of the belt. CONSTITUTION:A control unit 40 calculates the torque inputted from an engine to a continuously variable transmission by an input torque detecting means 51 by searching a torque map on the basis of the input engine revolution speed 45 and the throttle opening degree 42. When a comparing means 52 judges that the input torque supplied into the continuously variable transmission exceeds an allowable transmission torque of a belt, a transmission torque control means 53 reduces the speed change ratio of the continuously variable transmission, and further, if necessary, reduces the input torque supplied into the continuously variable transmission, namely the engine output torque. Therefore, the high output of the engine can be obtained, securing the reliability of the belt of a continuously variable transmission.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a control device for a vehicle equipped with a continuously variable transmission.

(Prior Art) Continuously variable transmissions have been known as transmissions for vehicles, in which a belt is stretched between a primary pulley and a secondary pulley of a variable effective diameter type consisting of a fixed conical plate and a movable conical plate. (For example, see Japanese Patent Laid-Open No. 52-98861). In such a continuously variable transmission,
Normally, a hydraulic pressing means is provided on the movable conical plate side of the primary pulley and the secondary pulley, and the pressing means controls the gear ratio by adjusting the effective diameter of the primary pulley. The maximum transmitted torque is controlled by adjusting the pressing force.

The gear ratio control described above is achieved by controlling the intake and discharge of hydraulic oil into the oil chamber of the pressing means on the primary pulley side using the gear ratio control valve, and the maximum transmission torque is controlled by the line pressure control valve using the line pressure control valve. This is done by controlling the

Incidentally, in recent years, vehicles equipped with continuously variable transmissions have been made more compact in order to improve fuel efficiency and reduce costs, and the transmission of continuously variable transmissions has become more compact in order to cope with higher engine output. There is a demand for increased torque.

On the other hand, the belt that transmits torque between the primary pulley and the secondary pulley has a specified torque (allowable transmission torque) that can be transmitted depending on conditions such as its shape and dimensions. In order to increase the torque to accommodate higher engine output, it is necessary to increase the radial dimension or width dimension of the belt, for example. However, if you do this,
As a result, the overall structure of the continuously variable transmission including the pulley becomes larger (in particular, the axial dimension increases), which goes against the demand for compactness. In other words, if we place importance on making the continuously variable transmission more compact and do not take measures to increase the allowable transmission torque as described above, the input torque to the continuously variable transmission will increase as the engine output increases. The permissible transmission torque is frequently exceeded, and as a result, the reliability of the belt strength is impaired. As described above, ensuring reliability in terms of belt strength and responding to higher engine output are contradictory elements, and as a result, it has been difficult to achieve both the problem of rain noise.

(Object of the Invention) The present invention aims to solve the problems pointed out in the above section of the prior art, and is intended to improve the reliability of the belt in a vehicle equipped with a continuously variable transmission consisting of a pair of variable pulleys and a belt. This was done with the aim of making it possible to respond to higher engine output while ensuring the same.

(Means for Achieving the Object) As a means for achieving the above object, the present invention includes a primary pulley and a secondary pulley whose effective diameter relative to the belt is variable, and the effective diameter of the pulley can be adjusted. In a vehicle equipped with a continuously variable transmission capable of controlling a gear ratio between a primary shaft and a secondary shaft, an input torque detection means for detecting an input torque of the continuously variable transmission, and the input torque detection means a comparison means for comparing the human power torque detected by the belt with the permissible transmission torque of the belt; The present invention is characterized by comprising a transmission torque control means for reducing the transmission torque to a value below the permissible transmission torque of the belt.

(Function) According to the present invention, when the input torque from the engine to the continuously variable transmission exceeds the permissible transmission torque of the belt, the transmission torque control means reduces the input torque itself to the continuously variable transmission, for example. The transmission torque in the continuously variable transmission is reduced to the above-mentioned allowable transmission torque or less by a method such as increasing the transmission speed or lowering the gear ratio in the continuously variable transmission.

(Effects of the Invention) Therefore, according to the control device for a vehicle equipped with a continuously variable transmission of the present invention, the transmission torque of the continuously variable transmission does not exceed the allowable transmission torque of the belt. This has the effect of being able to respond to higher engine output while ensuring reliability, and by extension, the reliability of the continuously variable transmission itself.

(Embodiments) Hereinafter, some preferred embodiments of the present invention will be described with reference to FIGS. The control concept will be explained with reference to FIG.

This control device ensures the reliability of the strength of the belt and increases the transmitted torque by preventing the torque transmitted through the belt (transmission torque) from exceeding the permissible transmission torque of the belt. This is what we are trying to achieve. As a specific means for this purpose, the control unit 40 includes a human torque detection means 51 that detects the human torque to the continuously variable transmission, and compares the input torque with a predetermined allowable transmission torque of the belt. Comparison means 52 for detecting the magnitude relationship, and transmission torque control means 53 for suppressing the transmission torque via the belt to below the permissible transmission torque when the human torque exceeds the permissible transmission torque according to the comparison means. .

As a method for reducing the transmission torque by the transmission torque control means 53, there is a method of lowering the gear ratio of the continuously variable transmission (in the case of the first embodiment described later), and a method of lowering the transmission gear ratio of the continuously variable transmission (in the case of the first embodiment described later), and a method of lowering the transmission gear ratio of the continuously variable transmission. (in the case of the second embodiment and the third embodiment described later). Note that control signals are input to the control unit 40 from a shift position sensor 41, a throttle opening sensor 42, a primary pulley rotation speed sensor 43, a secondary pulley rotation speed sensor 44, and an engine rotation speed sensor 45, respectively. . Hereinafter, control of the transmitted torque will be explained for each of the first to third embodiments.

First Embodiment A control device for a vehicle equipped with a continuously variable transmission according to a first embodiment of the present invention will be explained with reference to FIGS. 2 to 8. First, based on FIG. The overall configuration of the gear transmission will be briefly described.

(1) Overall configuration of continuously variable transmission This continuously variable transmission is a continuously variable transmission for front-wheel drive vehicles, and includes a torque converter B connected to the output shaft 1 of an engine A, a forward/reverse switching mechanism C, Belt transmission mechanism and reduction mechanism E
and a differential mechanism F.

■ = Torque converter B The torque converter B includes a pump impeller 3 fixed to one side of a pump cover 7 coupled to the engine output shaft 1 and rotates integrally with the engine output shaft 1, and a pump impeller 3. A turbine runner 4 is rotatably provided in a converter chamber 7a formed inside the pump cover 7 so as to face each other, and the turbine runner 4 is interposed between the pump impeller 3 and the turbine runner 4 to increase torque. The stator 5 has a stator 5 that performs the following steps. Further, the turbine runner 4 is connected to a carrier 15, which is a human-powered member of the forward/reverse switching mechanism C, which will be described later, via the turbine shaft 2, and the stator 5 is connected to the mission case I9 via the one-way clutch 8 and the stator shaft 9. connected.

Furthermore, a lock-up piston 6 is arranged between the turbine runner 4 and the pump cover 7. This lock-up piston 6 is slidably attached to the turbine shaft 2, and when hydraulic pressure is introduced into or discharged from the lock-up chamber 10, the lock-up piston 6 comes into contact with the pump cover 7 and becomes integrated with it. , and a converter state in which the converter is separated from the pump cover 7 are selectively realized. In the lock-up state, the engine output shaft 1 and the turbine shaft 2 are directly connected without fluid, and in the converter state, the engine torque is transmitted from the engine output shaft 1 to the turbine shaft 2 through fluid.

■; Forward/reverse switching mechanism The forward/reverse switching mechanism C operates in a forward state in which the rotation of the turbine shaft 2 of the torque converter B is directly transmitted to a belt transmission mechanism (to be described later), and in a reverse state in which the rotation is transmitted in a reverse state to the belt transmission mechanism. In this embodiment, this forward/reverse switching mechanism C is constituted by a double pinion type brane gear unit.

That is, the carrier I5 spline-coupled to the turbine shaft 2 has a first pinion gear 13 that meshes with the sun gear 12 and a second pinion gear 14 that meshes with the ring gear 11.
is installed. Incidentally, the sun gear 12 is spline-coupled to a primary shaft 22 of a belt transmission mechanism, which will be described later.

Further, a clutch 16 is provided between the ring gear 11 and the carrier 15 to connect and disconnect them, and a clutch 16 is provided between the ring gear 11 and the transmission case 19 to selectively connect the ring gear 11 with respect to the mission case 19. A brake 17 for fixing is provided respectively.

Therefore, when the clutch 16 is engaged and the brake 17 is released, the ring gear 11 and the carrier 15 are integrated, and the ring gear 11 is connected to the transmission case! Since the rotation of the turbine shaft 2 is allowed to rotate relative to the sun gear 12, the rotation of the turbine shaft 2 is assumed to be rotation in the same direction.
is output to the primary shaft 22 side (forward state).

On the other hand, when the clutch 16 is released and the brake 17 is engaged, the ring gear 11 is fixed to the transmission case 19 side and the ring gear 11 and the carrier 15 can rotate relative to each other, so that the turbine shaft 2 The rotation of the first pinion gear 13 and the second pinion gear 1
4 and is outputted to the sun gear 12 in an inverted state (backwards!!J). That is, in this forward/reverse switching mechanism C, switching between forward and backward travel is performed by selectively operating the clutch 16 and brake 17.

■: Belt transmission configuration The belt transmission mechanism is spaced apart from a primary pulley 21, which will be described later, arranged in the same ring shape on the rear side of the forward/reverse switching mechanism C, and in a direction parallel to the primary pulley 21. A belt 20 is stretched between the secondary pulley 31 and a secondary pulley 31, which will be described later.

III-a nib primary pulley 21 The primary pulley 21 is arranged on a primary shaft 22 which is arranged coaxially with the turbine shaft 2 and whose one shaft end is spline-coupled to the sun gear +2 of the forward/reverse switching mechanism C. To,
A fixed conical plate 23 having a predetermined diameter is integrally connected to the primary shaft 22, and a movable conical plate 24 is integrally connected to the primary shaft 22.
They are respectively movable in the axial direction relative to each other. The conical friction surface of the fixed conical plate 23 and the conical friction surface of the movable conical plate 24 constitute a belt receiving groove 21a having a substantially V-shaped cross section.

Further, a cylindrical cylinder 25 is fixed to the outer surface 24a side of the movable conical plate 24. Furthermore, this cylinder 25
A piston 26 fixed to the primary shaft 22 side is fitted in an oil-tight manner on the inner circumferential surface of the cylinder 25, and the piston 26 and the cylinder 25 form a movable circle. A primary chamber 27 is formed by the king of the plates 24. Note that line pressure is introduced into this primary chamber 27 from a hydraulic circuit (not shown).

The primary pulley 21 is connected to the belt 30 by moving its movable conical plate 24 in the axial direction by the pressure of the hydraulic oil introduced into the primary chamber 27 to increase or decrease the distance between the movable conical plate 24 and the fixed conical plate 23. The effective diameter can be adjusted.

m-b: Secondary pulley 31 The secondary pulley 31 basically has the same configuration as the primary pulley 21, and has a secondary pulley arranged parallel to and spaced apart from the primary shaft 22. - A fixed conical plate 33 is provided on the shaft 32 integrally with the secondary shaft 32, and a movable conical plate 34 is provided movably on the secondary shaft 32.

The conical friction surface of the fixed conical plate 33 and the conical friction surface 44a of the movable conical plate 34, which face each other, constitute a belt receiver N31a having a substantially V-shaped cross section.

Further, a substantially stepped cylinder 35 is coaxially fixed to the outer surface 34b of the movable conical plate 34. Also,
A piston 36, whose portion near the axis of the cylinder 35 is fixed to the secondary shaft 32, is fitted into the inner peripheral surface of the cylinder 35 in an oil-tight manner.

This piston 36, the cylinder 35, and the movable conical plate 34
A secondary chamber 37 is formed by these three members, and this secondary chamber 37 includes the primary pulley 2.
Similarly to the first side, line pressure is introduced from the hydraulic circuit. Similarly to the primary pulley 21, this secondary pulley 31 also has a movable conical plate 34 connected to a fixed conical plate 33.
The effective diameter of the belt 20 can be adjusted by moving it toward and away from the belt.

At this time, the pressure receiving area of the movable conical plate 34 is set to be smaller than that of the movable conical plate 24 of the primary pulley 21.

Further, since the speed reduction mechanism E and the differential mechanism F are conventionally known, a description of their structures will be omitted.

■Two shifts Next, I will briefly explain the operation of this continuously variable transmission Z.
Torque transmitted from the engine A via the torque converter B is transmitted to the belt transmission mechanism in the forward/reverse switching mechanism C with its rotational direction set to the forward direction or the reverse direction.

In belt transmission mechanism, primary pulley 2
When the effective diameter is adjusted by introducing or discharging hydraulic oil into the primary chamber 27 of 1, the secondary pulley 31, which is interlocked and connected to the primary pulley 21 via the belt 20, follows suit. Its effective diameter is adjusted by . That is, this primary
The gear ratio is controlled by adjusting the effective diameter of the pulley 21.

The gear ratio is controlled by an electromagnetic electromagnetic device that is duty-controlled based on a duty ratio output from a control unit, which controls the operation of a control valve that controls the suction and discharge of hydraulic oil from the primary pulley 21 into the primary chamber 27. This is done by controlling a solenoid valve.

The rotation of the secondary shaft 32 is further decelerated by the deceleration mechanism E, and then transmitted to the differential mechanism F, and from the differential mechanism F to the front axle (not shown).

(2) Transmission torque control of continuously variable transmission As described above, the continuously variable transmission of the i-th embodiment controls the transmission torque of the belt 20 to be equal to or less than its allowable transmission torque by controlling the gear ratio of the continuously variable transmission. The reliability of the belt 20 is ensured by controlling the transmission torque so that the transmission torque is controlled, and the actual transmission torque control will be explained below based on the flowchart shown in FIG.

First, after the control starts, in step S, the current shift position, throttle opening, engine speed, and primary pulley speed (i.e.,
Turbine rotation speed of torque converter B) and secondary
Read the pulley rotation speed (i.e. vehicle speed).

Next, as shown in Fig. 7, from the set primary pulley rotation speed map that has been set in advance using the vehicle speed and throttle opening as parameters for each shift position, the set primary that corresponds to the current vehicle speed and throttle opening is selected. - Calculate the pulley rotation speed (step S,).

Next, as shown in FIG. 5, the engine torque corresponding to the current engine speed and throttle opening is calculated from a torque map set using the engine speed and throttle opening as parameters (step S3).

Furthermore, in step S4, the torque ratio of the torque converter is calculated. That is, from the map showing the correlation between the speed ratio and torque ratio between the turbine runner 4 and the pump impeller 3 as shown in FIG. 6, the current speed ratio (i.e., expressed by the rotation speed of the primary pulley) is determined. Pump impeller 3 expressed by turbine speed and engine speed
Calculate the torque ratio with respect to the rotation speed of

Next, the human power shaft torque To that is actually applied to the continuously variable transmission is calculated from the engine torque and the torque ratio of the torque converter (step S).

Once the input shaft torque to the continuously variable transmission is determined, the next step is to determine the maximum gear ratio (i.e.,
The maximum gear ratio that can reduce the input shaft torque to less than the allowable transmission torque is determined from the map shown in FIG. That is, when the input shaft torque ('r, ), the maximum gear ratio is (i
, ), and if the belt is used at a higher gear ratio side (i.e., the area to the right of the line), the belt will be subjected to a torque greater than its allowable transmission torque, and the strength of the belt will not be affected. .

Next, this maximum gear ratio and the secondary pulley rotation speed (
From the vehicle speed), the primary pulley rotation speed at the maximum gear ratio, that is, the maximum primary pulley rotation speed is calculated (step S?).

Here, the maximum primary pulley rotation speed determined from the belt strength aspect is compared with the set primary pulley rotation speed determined from the map (Fig. 7), and the smaller of the two is set as the target primary pulley rotation speed to be controlled. - The number of revolutions of the pulley is set (step Sa). That is, the target gear ratio will never exceed the maximum gear ratio. Therefore, the deviation between this target primary pulley rotation speed and the current primary pulley rotation speed (actual primary pulley rotation speed) is calculated (step S8), and the duty rate for speed ratio control is set to 8. Step S: Calculate from the map shown in the figure. ), when the gear ratio is duty-controlled based on this, the transmission torque loaded on the belt is always less than the allowable transmission torque, ensuring the reliability of the belt and making it possible to cope with higher engine output.

Here, as described above, the belt transmission torque is feedback-controlled with the primary pulley rotational speed as the target, but it is also possible to perform feedback control with the gear ratio as the target, for example.

Second Embodiment The second embodiment differs from the first embodiment in that the transmission torque of the belt is kept below its allowable transmission torque by controlling the gear ratio to ensure its reliability. In contrast, by controlling the engine's output torque, the belt's transmission torque is set below the allowable transmission torque, but this is achieved by retarding the engine's ignition timing. This is Shino Nishi.

This engine output control will be explained with reference to the flow chart shown in FIG.

First, in step Q1, each control factor is read, and then the current engine torque is mapped (see Figure 5).
Then, the torque ratio of the torque converter is calculated from the map (see FIG. 6) (steps Q, ,Q,).

Then, from this engine torque and the torque ratio of the torque converter, the human power shaft torque To that is actually input to the continuously variable transmission side is calculated (step Q).

Next, the target primary pulley rotation speed is calculated from the current vehicle speed and throttle opening using the speed change knob (see Figure 7), and the primary pulley rotation speed and vehicle speed (secondary pulley rotation speed) are calculated from the current vehicle speed and throttle opening. ) from which the target gear ratio (i) is calculated (step Q,).

Next, the input shaft torque corresponding to this gear ratio (i) (in this second embodiment, the input shaft torque corresponding to this gear ratio corresponds to the allowable transmission torque allowed in terms of belt strength) is calculated using the map shown in Fig. 4. (Step Q,). That is, for example, when the gear ratio is (il), the allowable transmission torque is (T, ).

Next, the above allowable transmission torque T, and the above input shaft torque (
(Step Q?). And To<
If it is TI, that is, the human shaft torque To is in the usable range below the line L indicating the belt's usage limit, so no control is performed in this case.

On the other hand, if T o > T I, it means that the human power shaft torque TO is in the unusable area above line L in Figure 4, and the reliability of the belt strength cannot be ensured if this continues. become. Therefore, in this case, the first O
Calculate the retard amount of the engine's ignition timing from the [torque deviation - retard amount] map shown in the figure (step Q,
). Then, the ignition timing is retarded by this retard amount (step Q,), thereby reducing the engine output and suppressing the human power shaft torque To from the engine side to the continuously variable transmission to below the above-mentioned allowable transmission torque T1, thereby reducing the belt This ensures reliability in terms of strength.

Third Embodiment The third embodiment differs from the second embodiment in that it retards the engine ignition timing when the input shaft torque to the continuously variable transmission exceeds the allowable transmission torque specified by the strength of the belt. In contrast, when the input shaft torque exceeds the allowable transmission torque, the fuel supply to the engine is immediately cut off, thereby reducing the engine output. This is what I did.

To explain this control with reference to FIG. 11, step R
The method of calculating the human shaft torque (To) and belt allowable transmission torque (T1) from Step 1 to Step R is the same as in the second embodiment.

Input shaft torque (To) and belt allowable transmission torque (T,
) is determined, the input shaft torque (
To) and the belt's allowable transmission torque (T) corresponding to the gear ratio.
, ), and if T o > T +, a fuel cut is performed and the output torque of the engine is reduced (step R,). This fuel cut is continued until To<T.

In addition to the method of retarding the ignition timing of the engine and the method of cutting fuel as described above, there are various methods for reducing the engine output.
For example, in a configuration in which the throttle valve and accelerator pedal are operated in conjunction with each other via an electrically controlled actuator, when the input shaft torque to the continuously variable transmission exceeds the allowable transmission torque of the belt, It is also possible to make the opening degree of the throttle valve relative to the amount of depression of the accelerator pedal smaller than usual.

[Brief explanation of the drawing]

Fig. 1 is a functional block diagram of the control device of the present invention, Fig. 2 is a system diagram of a continuously variable transmission provided in the control device according to the first embodiment of the present invention, and Fig. 3 is a system diagram of the control device according to the first embodiment of the present invention. Control flowchart diagram, Figure 4 is the "gear ratio - human shaft torque" map, Figure 5 is the "engine rotation speed - torque" map, and Figure 6 is the "speed ratio - human shaft torque" map.
The figure shows the "speed ratio-torque ratio" map of the torque converter.
FIG. 7 is a shift map, FIG. 8 is a duty rate map, FIG. 9 is a control flowchart of the control device according to the second embodiment of the present invention, FIG. 10 is a retard amount map, and FIG. 11 is a diagram of the present invention. It is a control flowchart figure of the control apparatus based on the 3rd Example of. 1... Engine output shaft 2... Turbine shaft 3... Pump impeller 4... Turbine runner 5... Stator 11... Ring gear! 2...Sun gear 13.14...Conflict pinion gear l5...l6...l7...20...2 l...22...22...3 I...32...32... A ・ ・ ・ ・ B ・ ・ ・ ・ Cφ ・ ・ ・ D ・ ・ ・ E ・ ・ ・ ・ F ・ ・ ・ ・ O ・Carrier clutch・Brake belt・Primary pulley・Primary shaft・Secondary pulley・Secondary shaft, engine, torque converter, forward/reverse switching mechanism, belt transmission mechanism, deceleration mechanism, differential mechanism Figure 5 Vehicle speed deviation +

Claims (1)

[Claims] 1. Equipped with a continuously variable transmission that is equipped with a primary pulley and a secondary pulley whose effective diameter relative to the belt is variable, and whose gear ratio between the primary shaft and the secondary shaft can be controlled by adjusting the effective diameter of the pulley. In the vehicle, an input torque detection means for detecting an input torque of a continuously variable transmission, a comparison means for comparing the input torque detected by the input torque detection means and an allowable transmission torque of the belt, and the comparison means and transmission torque control means for reducing the transmission torque of the continuously variable transmission to below the permissible transmission torque of the belt when it is detected that the input torque is greater than the permissible transmission torque. A control device for a vehicle equipped with a continuously variable transmission.