JP2001330113A - Variable speed controller for continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce energy consumed in an oil pump for a variable speed operation for a belt type continuously variable transmission to enhance power transmission efficiency. SOLUTION: A belt 17 is laid between a primary pulley 15 and a secondary pulley 16, a primary cylinder 22 having a primary oil chamber 23 is provided in the primary pulley 15, and a secondary cylinder 25 having a secondary oil chamber 26 is provided in the secondary pulley 16. A line pressure passage 28 for guiding a hydraulic fluid from the oil pump 27 is connected to the first port 31a of a reversible hydraulic motor 30, a primary pressure passage 35 connected to the primary oil chamber 23 is connected to the first port 34a of a reversible hydraulic pump 33, the reversible pump 30 is a variable displacement type, and a flow rate of the hydraulic fluid flowing in the motor 30 is regulated in the motor 30 by a control signal from a control unit 70 to perform speed variable control.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift control device for a belt-type continuously variable transmission suitable for use in shift control of a mobile machine such as an automobile.

[0002]

2. Description of the Related Art A belt-type continuously variable transmission (CV) for automobiles.
T), a metal pulley provided between the primary pulley having a variable pulley groove width provided on the primary shaft on the driving side and a secondary pulley having a variable pulley groove width provided on the secondary shaft on the driven side, that is, the driven side. In some belts, the pulley diameters of a primary pulley and a secondary pulley are changed by hydraulic pressure to change the rotational speed of a secondary shaft steplessly.

The shift control of the CVT is performed by controlling the hydraulic pressure supplied to a primary cylinder provided on a primary pulley and a secondary cylinder provided on a secondary pulley, and the hydraulic pressure supplied to each cylinder is controlled. Is generated by an oil pump driven by the engine. The line pressure supplied to the secondary cylinder, that is, the secondary pressure is regulated by a secondary pressure regulating valve, and the primary pressure supplied to the primary cylinder is regulated by the primary pressure regulating valve using the line pressure as an original pressure. By adjusting the primary pressure to a value corresponding to the target gear ratio and gear speed, the vehicle speed is controlled by changing the groove width of the primary pulley, and the line pressure is adjusted to a value commensurate with the transmission capacity required for the belt. You.

[0004] The primary pressure is regulated by reducing the line pressure and does not exceed the line pressure. Therefore, in order to adjust the pulley groove width so that the pulley ratio increases, the clamping force of the primary pulley must be larger than the clamping force of the secondary pulley. It is about twice as large as the cylinder.

[0005]

Accordingly, when the groove width of the primary pulley is adjusted by the primary pressure obtained by reducing the line pressure as the original pressure as in the prior art, the downshift is performed. When performing, the primary pressure hydraulic oil is leaked or discarded to reduce the primary pressure, and the discharge pressure from the oil pump flows into the secondary cylinder. At this time, the primary cylinder is obtained by the product of the primary pressure and the pulley stroke It does work, but all of this is consumed as passage resistance of the primary pressure regulating valve, which is a pressure reducing valve.

As described above, when the pulley ratio is controlled by the primary pressure regulating valve which is a hydraulic valve, the pulley ratio control can perform the shift control with a small force and a high response, but the hydraulic oil always leaks. In order to perform
A power transmission loss occurs, and about one-third to one-half of the power consumed by the oil pump, which is the energy supply source of hydraulic oil, is C.
This is a VT power transmission loss.

A technique in which the groove width of the primary pulley is adjusted by an electric motor via a screw mechanism has been proposed, for example, as disclosed in Japanese Patent Application Laid-Open No. 3-213762. In this case, the motor torque is converted into the axial movement of the movable pulley of the primary pulley to press the belt, but this technique is effective when a hydraulic cylinder is not used for pulley ratio control. If the clamping force of the secondary pulley is generated by the hydraulic cylinder in combination with the hydraulic control, the pump loss cannot be reduced at the time of downshift because the same cylinder operation flow rate as that of the above-described conventional technique is required. .

[0008] Further, as disclosed in this publication, the system in which the clamping force is not generated by hydraulic pressure can be used when the friction coefficient between the pulley and the belt is large and the belt clamping force is small, such as a rubber belt. However, the CVT using a metal belt has a small coefficient of friction and requires a large clamping force. Therefore, in such a method, the strength of the screw portion and the bearing is insufficient, so the device must be enlarged. In addition, the frictional resistance increases with an increase in size, which is disadvantageous as compared with a case where a clamping force is generated by hydraulic pressure.

It is an object of the present invention to reduce the energy consumed by an oil pump for the shifting operation of a belt-type continuously variable transmission and improve the power transmission efficiency.

[0010]

SUMMARY OF THE INVENTION According to the present invention, there is provided a transmission control apparatus for a continuously variable transmission, comprising: a primary pulley mounted on a primary shaft and having a variable pulley groove width; A variable speed control device of a continuously variable transmission having a pulley groove width variable secondary pulley over which a belt is wound, wherein the primary pulley is provided with a primary cylinder having a primary oil chamber, and the secondary pulley is provided with the secondary pulley. A second cylinder having a secondary oil chamber, a first port communicating with a line pressure path supplying hydraulic oil of a line pressure from a hydraulic pressure source to the secondary oil chamber, and an oil path connected to a hydraulic oil storage portion. A reversible hydraulic motor having a second port that communicates with a first port communicating with a primary pressure passage connected to the primary oil chamber. A reversible hydraulic pump connected to the reversible hydraulic motor and a reversible hydraulic pump connected to the reversible hydraulic motor, and a hydraulic oil flowing through the reversible hydraulic pump. It is characterized by having a variable displacement mechanism for changing the amount and a shift control means for controlling the operation of the variable displacement mechanism.

In the transmission control device for a continuously variable transmission according to the present invention, a belt is stretched between a primary pulley mounted on a primary shaft and having a variable pulley groove width and a secondary shaft mounted on the secondary shaft. A shift control device for a continuously variable transmission having a secondary pulley having a variable pulley groove width, comprising: a primary cylinder provided on the primary pulley and having a primary oil chamber; and a secondary cylinder provided on the secondary pulley and having a secondary oil chamber. A first port including a secondary cylinder, a first port communicating with a line pressure path that guides hydraulic oil of line pressure from a hydraulic pressure source, and a second port communicating with an oil path connected to the hydraulic oil storage unit. A reversible hydraulic motor, a first port communicating with a primary pressure passage connected to the primary oil chamber, and the hydraulic oil storage portion; A first reversible hydraulic pump connected to the first reversible hydraulic motor, a first port communicating with the line pressure path, and the hydraulic oil storage unit. A second reversible hydraulic motor having a second port communicating with an oil passage connected to the second oil chamber, and a first port communicating with a secondary pressure passage connected to the secondary oil chamber and the hydraulic oil storage portion. And a second port connected to the second reversible hydraulic motor, and a second reversible hydraulic pump connected to the second reversible hydraulic motor, and flowing through the first reversible hydraulic motor or the first reversible hydraulic pump. A first variable displacement mechanism that changes the amount of hydraulic oil; a second variable displacement mechanism that changes the amount of hydraulic oil flowing through the second reversible hydraulic motor or the second reversible hydraulic pump; Work of variable capacity mechanism And having a shift control means for controlling.

In the transmission control apparatus for a continuously variable transmission according to the present invention, a variable displacement mechanism may be incorporated in the reversible hydraulic motor or the reversible hydraulic pump to form a variable displacement reversible hydraulic motor or a variable displacement reversible hydraulic pump. The motor or the reversible hydraulic pump may have a fixed displacement, and a continuously variable transmission may be provided between them.

The oil pressure source may be constituted by an oil pump driven by an engine, or may be constituted by an oil pump driven by an electric motor and a pressure accumulator.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is a schematic diagram showing an example of a drive system of a belt-type continuously variable transmission, that is, a CVT. The rotation of a crankshaft 1 driven by an engine not shown is used as a starting device. Is transmitted to the continuously variable transmission mechanism 4 via the torque converter 2 and the forward / reverse switching mechanism 3.

The torque converter 2 has a lock-up clutch 5, which is connected to a turbine shaft 6. One side of the lock-up clutch 5 is an apply chamber 7a, and the other side is a release chamber 7b, and the hydraulic pressure supplied into the release chamber 7b is applied to the apply chamber 7a.
By circulating through the a, the torque converter 2 is in an operating state. On the other hand, by supplying hydraulic pressure to the apply chamber 7a and reducing hydraulic pressure in the release chamber 7b, the lock-up clutch 5 is engaged with the front cover 8 to be in a lock-up state. By adjusting the pressure in the release chamber 7b, slip pressure control is performed so that the lock-up clutch 5 is slid.

The forward / reverse switching mechanism 3 includes a forward clutch 11 for transmitting the rotation of the turbine shaft 6 as an output shaft of the torque converter 2 to the continuously variable transmission mechanism 4 in a forward direction, and a reversing clutch for transmitting the rotation in a reverse direction. And a brake 12 for supplying a hydraulic pressure to the clutch oil chamber 11a to
Is connected, the rotation of the turbine shaft 6 is transmitted to the continuously variable transmission mechanism 4 in the forward direction. When the reverse brake 12 is connected by supplying hydraulic pressure to the brake oil chamber 12a and transmitted in the reverse direction, the rotation is transmitted. Is done.

The continuously variable transmission mechanism 4 has an input shaft or primary shaft 13 connected to the forward / reverse switching mechanism 3, and an output shaft or secondary shaft 14 parallel to the input shaft.
A primary pulley 15 is provided on the primary shaft 13. The primary pulley 15 is slidable in the axial direction by a ball spline or the like on the primary shaft 13 opposed to the fixed pulley 15 a fixed to the primary shaft 13. The pulley has a movable pulley 15b, and the gap between the cone surfaces of the pulley, that is, the pulley groove width is variable. A secondary pulley 16 is provided on the secondary shaft 14, and the secondary pulley 16 slides in the axial direction on the secondary shaft 14 in opposition to the fixed pulley 16a fixed to the secondary shaft 14 like the movable pulley 15b. A movable pulley 16b that is freely mounted, and the groove width of the pulley is variable.

A belt 17 is stretched between the primary pulley 15 and the secondary pulley 16, and by changing the groove width of both pulleys 15, 16, the ratio of the winding diameter to the respective pulleys 15, 16 is changed. Is changed, the rotation of the primary shaft 13 is transmitted to the secondary shaft 14 at a continuously variable speed.

The rotation of the secondary shaft 14 is transmitted to wheels 19a and 19b via a gear train having a reduction gear and a differential device 18. In the case of a front-wheel drive vehicle, the wheels 19a and 19b are connected to the front wheels. Becomes
The basic structure of such a CVT drive system is disclosed in, for example, JP-A-10-325458.

In order to change the groove width of the primary pulley 15, a plunger 21 having a cylindrical portion and a disk portion is fixed to the primary shaft 13, and the plunger 21 is fixed to the primary shaft 13.
Primary cylinder 22 that slidably contacts the outer peripheral surface of the cylinder
Is fixed to the movable pulley 15b, and the plunger 21
A primary oil chamber 23 is formed between and the movable pulley 15b.

To change the groove width of the secondary pulley 16, a plunger 24 having a tapered cylindrical portion is fixed to the secondary shaft 14, and a secondary cylinder 25 slidably contacting the outer peripheral surface of the plunger 24. It is fixed to the movable pulley 16b, and a secondary oil chamber 26 is formed between the plunger 24 and the movable pulley 16b.

When hydraulic oil is supplied into the primary oil chamber 23 in the primary cylinder 22 to increase its volume,
The movable pulley 15b is fixed to the fixed pulley 1 together with the cylinder 22.
The width of the pulley groove is reduced by moving to the 5a side, and the pulley groove width is increased when the volume is reduced. Further, the movable pulley 16b supplies hydraulic oil into the secondary oil chamber 26 in the secondary cylinder 25 to increase the volume thereof.
At the same time, it moves to the fixed pulley 16a side to reduce the pulley groove width. If the volume is reduced, the pulley groove width increases.

FIG. 2 is a hydraulic circuit diagram for performing a shift operation by supplying hydraulic oil to the primary cylinder 22 and the secondary cylinder 25, and a discharge port of a main hydraulic pump, that is, an oil pump 27 driven by an engine has a line pressure. A line 28 is connected to a pressure adjusting port of a line pressure adjusting valve 29 via a passage 28, and the line pressure (secondary pressure) is adjusted by the line pressure adjusting valve 29. The line pressure passage 28 is connected to the secondary oil chamber 26 in the secondary cylinder 25.
And the line pressure generates a belt clamping force of the secondary pulley 16.

The line pressure path 28 is connected to the first port 31a of the variable displacement reversible hydraulic motor 30, and the line pressure can cause the hydraulic motor 30 to generate torque.
The hydraulic motor 30 is connected to a reversible hydraulic pump 33 by a connecting shaft 32.
The reversible hydraulic pump 33 can be driven by the torque generated by the hydraulic motor 30. The first port 34 a of the hydraulic pump 33 is connected to the primary oil chamber 23 in the primary cylinder 22 by a primary pressure path 35, and the primary pressure discharged from the hydraulic pump 33 can generate a clamping force of the primary pulley 15. it can.

The second port 31b of the hydraulic motor 30 and the second port 34b of the hydraulic pump 33 are connected to an inflow oil passage for supplying the hydraulic oil in the oil pan 36 to the inflow port of the oil pump 27 via the strainer 37. Guide oil passage 38
The connection end of the guide oil passage 38 is between the strainer 37 and the inflow port of the oil pump 27.

The hydraulic motor 30 and the hydraulic pump 33 are both reversible, and when hydraulic fluid is supplied into the primary oil chamber 23 when the groove width of the primary pulley 15 is reduced, the first port 31a is used. The hydraulic motor 30 is driven by the inflowing line pressure, and the hydraulic pump 33 is driven by the hydraulic motor 30 to pressurize the hydraulic oil in the oil pan 36 as a hydraulic oil accommodating portion to the primary pressure and into the primary oil chamber 23. Supplied.

On the other hand, when the hydraulic oil is discharged from the primary oil chamber 23 when the groove width of the primary pulley 15 is widened, the hydraulic pump 33 functions as a hydraulic motor and is operated by the hydraulic oil flowing from the first port 34a. The hydraulic pump 33 is driven, and the hydraulic motor 30 functioning as a hydraulic pump is driven by the hydraulic pump 33 to discharge hydraulic oil from the first port 31a to the line pressure path 28. The hydraulic oil flowing into the line pressure passage 28 is supplied into the secondary oil chamber 26 together with the hydraulic oil from the oil pump 27.

As described above, the hydraulic motor 30 and the hydraulic pump 33 are reversible hydraulic motor pumps having functions as a hydraulic motor and a hydraulic pump, respectively.

A lubricating pressure adjusting valve 39 is provided between the drain port of the line pressure adjusting valve 29 and the inflow port of the oil pump 27, and the lubricating pressure supplied to the lubricating pressure passage 41 is applied to the drain of the line pressure adjusting valve 29. The pressure is adjusted as the original pressure, and the lubricating hydraulic oil is supplied to the lubricating portion of the forward / reverse switching mechanism 3, the lubricating portion of the belt 17, and the like. Further, a clutch pressure adjusting valve 42 is connected to the line pressure path 28,
The clutch pressure is adjusted by the clutch pressure adjusting valve 42 using the line pressure as the original pressure. The hydraulic oil of this clutch pressure is supplied to the clutch oil chamber 11a of the forward clutch 11 of the forward / reverse switching mechanism 3, the brake oil chamber 12a of the reverse brake 12 and the apply chamber 7a of the lock-up clutch 5 via the clutch pressure path 42a. It is being supplied.

The hydraulic circuit for supplying the hydraulic oil of the clutch pressure and the lubricating pressure to the forward / reverse switching mechanism 3 and the like is the same as that disclosed in the aforementioned Japanese Patent Application Laid-Open No. 10-325458.

FIG. 3 shows a hydraulic motor 30 and a connecting shaft 32
FIG. 3 is a cross-sectional view showing a hydraulic pump 33 connected by
FIG. 4 shows the hydraulic motor 3 in a direction along the line IV-IV in FIG.
0 is a sectional view, and FIG. 5 is a sectional view of the hydraulic pump 33 along a line VV in FIG.

A hydraulic motor 30 is incorporated in a cover 44 fixed to one end of a casing 43 for rotatably housing the connecting shaft 32, and a cover 4 fixed to the other end.
5 has a hydraulic pump 33 incorporated therein. Connecting shaft 32
A rotor 46 of the hydraulic motor 30 attached to one end of the hydraulic motor 30 is rotatably accommodated in the casing 43, and a plurality of vanes 47 are mounted on the rotor 46 so as to be reciprocally movable in the radial direction. A cam ring 48 is arranged outside the rotor 46, and the vane 47 slides along the inner peripheral surface of the cam ring 48, and is formed between the outer peripheral surface of the rotor 46 and the inner peripheral surface of the cam ring 48. A first port 31a to which the line pressure passage 28 is connected and a guide oil passage 3
8 communicates with a second port 31b to which it is connected.

As a result, the fluid energy of the hydraulic oil flowing into the oil chamber from the line pressure passage 28 through the first port 31a is converted into the rotational kinetic energy of the rotor 46, and the rotational energy is changed in the direction indicated by the arrow in FIG. 46 is driven to rotate.

The cam ring 48 is rotatably mounted on the casing 43 by a pin 51. In order to press the respective vanes 47 against the inner peripheral surface of the cam ring 48, a step formed on both end surfaces of the rotor 46 is provided. Support ring 52
Is assembled. Therefore, when the cam ring 48 is rotated about the pin 51, the amount of eccentricity of the cam ring 48 with respect to the rotor 46 changes, so that the discharge capacity can be changed, and the hydraulic motor 30 is of a variable displacement type.

In order to change the amount of eccentricity, a male screw shaft 54 rotationally driven by an electric motor 53 for shifting is provided in the casing 43 in a direction perpendicular to the connecting shaft 32, and is screwed to the male screw shaft 54. The slider 55 that is moved in the axial direction is engaged with the cam ring 48. The slider 55 is formed with an engagement groove 57 into which a projection 56 provided on the cam ring 48 enters.
Is engaged with a groove formed in the projection 56.

As described above, the amount of eccentricity of the cam ring 48 with respect to the rotor 46 is adjusted by the tangential screw mechanism including the electric motor 53 for shifting, the male screw shaft 54, and the slider 55. The tangential screw mechanism in which the slider 55 is screw-coupled to the male screw shaft 54 transmits the rotation of the electric motor 53 to the slider 55, and is an irreversible mechanism in which the male screw shaft 54 does not rotate due to the axial load of the slider 55. ing.

A rotor 61 of the hydraulic pump 33 fixed to the other end of the connecting shaft 32 is rotatably accommodated in the casing 43, and a plurality of vanes 62 are mounted on the rotor 61 so as to be reciprocally movable in the radial direction. ing. A cam ring 63 is arranged outside the rotor 61, and the vane 62 is
The cam ring 63 is fixed to the casing 43 by a fixing pin 64 and its rotation is regulated. In order to press each of the vanes 62 against the inner peripheral surface of the cam ring 63, a support ring 65 is attached to a step formed on both end surfaces of the rotor 61. Thus, the hydraulic pump 33 is a fixed displacement vane pump.

An oil chamber formed between the outer peripheral surface of the rotor 61 and the inner peripheral surface of the cam ring 63 has a primary pressure passage 35
Is connected to a second port 34b to which the guide oil passage 38 is connected.

Accordingly, the rotor 46 is connected to the connecting shaft 32.
When is rotated in the direction indicated by the arrow in FIG. 4, the rotational kinetic energy is converted into fluid energy, and the primary pressure working fluid is discharged from the first port 34a to which the primary pressure passage 35 is connected.

On the other hand, the rotor 61 of the hydraulic pump 33 is driven by the primary pressure flowing from the first port 34a as shown in FIG.
When rotated in the direction opposite to the direction of the arrow in,
It functions as a hydraulic motor and drives the hydraulic motor 30 shown in FIG. 4 to rotate in the direction opposite to the arrow. At this time, hydraulic oil is discharged into the line pressure passage 28.

Therefore, according to the control signal from the control unit, a control signal is sent to the solenoid of the line pressure adjusting valve 29 to adjust the line pressure, and a control signal is sent to the electric motor 53 for shifting to adjust the primary pressure. Thus, it is possible to perform the shift control according to the driving situation.

Each of the support rings 52, 65 has a function of pressing the vanes 47, 62 against the inner peripheral surfaces of the cam rings 48, 63 against the discharge pressure to prevent leakage of hydraulic oil from the tip of the vane. However, depending on the application, the hydraulic oil becomes high oil pressure, and the contact between the vane and the cam ring cannot be maintained only by the elastic force of the support rings 52 and 65.
In such a case, by guiding the oil pressure to the inner diameter side of the vane, the oil pressure can push the vane in the outer diameter direction.

FIG. 6 shows the operation of the vane 4 by hydraulic pressure as described above.
Hydraulic motor 30 of the type for pushing out 7, 62
FIG. 9 is a sectional view showing a modified example of the hydraulic pump 33 and an oil passage 6 formed in a cover 44 for the hydraulic motor 30.
6, the line pressure is guided to the inner diameter side of the vane 47, and the hydraulic pump 33 is configured to guide the primary pressure to the inner diameter side of the vane 62 by an oil passage 67 formed in the cover 45.

FIG. 7 is a block diagram showing a control unit 70 for inputting an instruction value to the shift electric motor 53 to control the shift of the CVT, and includes an engine speed signal 71, a throttle opening signal 72, and a primary rotation. Number signal 73, secondary rotation speed signal 74, range switch signal 75, brake switch signal 76, oil temperature sensor signal 7
7. A control signal is sent to the electric motor 53 for shifting based on the line pressure sensor signal 78.

The input torque calculator 81 calculates the engine torque based on the engine speed signal 71, the throttle opening signal 72, and the primary speed signal 73. The input torque calculator 81 calculates the engine torque based on the ratio of the engine speed to the primary speed. The effect of the launching device is taken into account.

The target pulley ratio setting section 82 includes driver operation signals such as a throttle opening signal 72, a range switch signal 75, and a brake switch signal 76, a primary speed signal 73, a secondary speed signal 74, and an oil temperature sensor. A target pulley ratio is calculated from a state signal such as the signal 77 and output.

The actual pulley ratio calculator 83 calculates the actual pulley ratio based on the primary rotation speed signal 73 and the secondary rotation speed signal 74.

The target oil pressure ratio setting section 84 receives the input torque signal obtained by the input torque calculation section 81, the line pressure sensor signal 78, the target pulley ratio signal calculated by the target pulley ratio setting section 82, and the actual pulley ratio. Based on the actual pulley ratio signal obtained by the ratio calculator 83, a hydraulic ratio (a hydraulic ratio between the primary oil chamber 23 and the secondary oil chamber 26) for realizing the target pulley ratio is output.

The motor control unit 85 controls the electric motor 53 for shifting so as to realize the amount of eccentricity of the hydraulic motor 30 calculated from the target hydraulic pressure ratio, and calculates a PID based on the deviation between the actual pulley ratio and the target pulley ratio. The output from the section 86 corrects and controls the electric motor 53 for shifting to achieve the target pulley ratio.

Assuming that the line pressure acting on the variable displacement reversible hydraulic motor 30 is Ps and the discharge volume per rotation of the hydraulic motor 30 is Dm (variable), the generated torque Tg of the hydraulic motor 30 is expressed by the following equation (1). expressed.

Generated torque Tg = Ps × Dm / 2 / π (1) On the other hand, the torque Tn required for the reversible hydraulic pump 33 to generate the primary pressure Pp is determined by the discharge volume per rotation of the hydraulic pump 33. Dp is expressed by the following equation (2).

Required torque Tn = Pp × Dp / 2 / π (2) The variable displacement reversible hydraulic motor 30 and the reversible hydraulic pump 33
Are connected by the connection shaft 32, the following equation (3) is derived from the balance of the torque.

Ps × Dm = Pp × Dp (3) By transforming equation (3) and displaying the primary pressure Pp, (3)
a) Equation is obtained.

Pp = (Dm / Dp) × Ps (3a) By controlling Dm from the equation (3a), the primary pressure Pp
Can be variably controlled.

When the input torque fluctuates due to an external factor, the control circuit adjusts the line pressure Ps to maintain the belt clamping force optimally, and also changes the primary pressure Pp to the hydraulic pressure ratio Pp / to stabilize the gear ratio. It is necessary to follow up so that Ps becomes constant. However, as shown by the equation (3a), the capacity ratio of the hydraulic motor / hydraulic pump defines the hydraulic ratio, and even if the line pressure Ps fluctuates, automatic operation is performed. Since the primary pressure Pp follows, the stability of the speed ratio can be improved.

The tangential screw mechanism is an irreversible mechanism of the rotor, and the motor 5
Even if the torque is lost due to the disconnection of No. 3 or the like, the cam ring 48 maintains its position, so that abrupt shift does not occur and it is safe.

Next, the dynamic behavior of the shift process will be described.

The upshift is performed by increasing the primary pressure Pp, and can be achieved by displacing the cam ring 48 in the direction of arrow U in FIG. At this time, the hydraulic motor 3
0 drives the hydraulic pump 33 while consuming the line pressure,
The hydraulic pump 33 sends the primary pressure Pp into the primary cylinder 22 to displace the pulley groove width of the primary pulley 15. When the relationship between the primary pressure Pp and the line pressure Ps satisfies the expression (3a), the hydraulic motor 3
Operation of 0 stops and equilibrium is reached.

On the other hand, at the time of a downshift, when the cam ring 48 is displaced in the direction shown by the arrow D in FIG.
The torque of the hydraulic motor 30 decreases, and the torque balance is lost. That is, the hydraulic pump 3 is driven by the primary pressure Pp.
3, the reversible hydraulic pump 33 generates a reverse rotation torque by the primary pressure Pp, and the hydraulic motor 3
0 is driven in the reverse direction, and hydraulic oil is returned from the hydraulic motor 30 to the line pressure path 28. That is, at the time of downshift, the hydraulic pump 33 functions as a hydraulic motor, and the hydraulic motor 30 functions as a hydraulic pump.

Conventionally, a sudden downshift is required at the time of sudden braking or the like, so that the oil pump 27 needs to be set to a capacity that can correspond to the stroke speed of the secondary cylinder 25. However, according to the present invention, In the case of a downshift, the supply flow rate is assisted by the reverse rotation operation (operation as a pump) of the hydraulic motor 30, so that even if the capacity of the oil pump 27 is set small, the downshift speed does not become insufficient. Since the oil pump 27 is constantly driven, reducing the size of this pump
This has the effect of reducing the loss torque of the CVT and improving fuel economy.

Next, the assisting action of the working flow rate at the time of the downshift will be specifically described with reference to FIGS.

FIG. 8 shows the displacement of the pulley groove width of the primary pulley 15 and the secondary pulley 16 with respect to the pulley ratio of a certain belt type CVT, that is, the respective movable pulleys 15b,
16b shows the displacement amount. In FIG. 8, the position of the pulley at the time of overdrive OD is set to 0, and the primary stroke 1 which is the displacement of the primary pulley 15 is set.
5S and the change of the secondary stroke 16S, which is the displacement of the secondary pulley 16, from OD to LOW.
The primary stroke and the secondary stroke at the time of shifting to are different from each other, which indicates that the primary stroke and the secondary stroke have different properties from a simple opposed piston. For this reason, it is difficult to verify the flow rate of the hydraulic oil at the time of shifting by a mathematical expression, and a change in the flow rate of the hydraulic oil by numerical calculation assuming various specifications can be shown in FIG.

FIG. 9 is a characteristic diagram showing a simulation of the flow rate of hydraulic oil when downshifting at a constant deceleration. The dashed line i indicates the deceleration at which the engine speed is maintained at a minimum value. It shows the change in the pulley ratio i when downshifting, and the change i (t) in the pulley ratio i is as follows: the initial value of the secondary rotation speed is NS0, the deceleration is g, and the primary rotation speed is NP0 (constant value). Then, a hyperbola as expressed by the following equation (4) is obtained.

I (t) = NP0 / (NS0−g · t) (4) In order to change the pulley ratio i at such a deceleration, a thin line Qp from the primary oil chamber 23 in the primary cylinder 22 is used. It is necessary to discharge the hydraulic oil as shown, and it is necessary to supply the hydraulic oil to the secondary oil chamber 26 in the secondary cylinder 25 as shown by a broken line Qs.

In the prior art described above, the required oil supply amount indicated by the broken line Qs must be directly supplied from the oil pump 27 into the secondary cylinder 25,
Must have the required supply oil volume.

On the other hand, according to the present invention, when the downshift is performed, the hydraulic pump 33 is driven by the hydraulic pressure discharged from the primary cylinder 22 as a hydraulic motor, so that the hydraulic motor 3 functioning as a hydraulic pump is driven.
0 can be supplied to the secondary cylinder 25 from the hydraulic pressure returned to the line pressure passage 28, and the oil pump 27
Therefore, a sudden downshift can be achieved only by supplying a small pump capacity indicated by the thick line Qinv into the secondary cylinder 25.

At the time of this shifting operation, the shifting electric motor 53 does not directly generate hydraulic pressure, and has a booster effect by the tangential screw mechanism and irreversibility due to the screw connection of the male screw and the female screw, and the rotor 55 has a slider reaction force. And the effect of maintaining the posture by not changing the position is obtained, so that the shift operation can be performed by the small electric motor 53.

The supply oil amount Qinv of the present invention is obtained as follows. That is, the reverse rotation speed N (t) of the hydraulic pump 33 at the time of the downshift is expressed by the following expression (5), where the discharge flow rate Qp from the primary cylinder 22 is Qp (t).

N (t) = Qp (t) / Dp (5) The flow rate Q (t) to be supplied to the line pressure passage 28 when the hydraulic motor 30 is driven in reverse rotation is determined by the capacity of the variable displacement reversible hydraulic motor 30 as Dm. (t) is expressed by the following equation (6).

Q (t) = N (t) × Dm (t) = Qp (t) × Dm (t) / Dp (6) Here, the capacity Dm (t) of the variable displacement reversible hydraulic motor 30 is predetermined. The change in time is given so that the shift speed can be obtained.
The characteristic line Qinv of the present invention is represented by Q (t) -Q, where Qs (t) is the flow rate required for the secondary stroke indicated by the characteristic line Qs.
It is obtained by plotting s (t).

The hydraulic motor 30 and the hydraulic pump 33 described above are not limited to the types shown in the drawings. For example, the fixed capacity reversible hydraulic pump may be an internal or external gear type, an axial piston type in addition to a vane type. ,
A radial piston type or the like can be used. Also,
As the variable displacement reversible hydraulic motor, an axial piston type or a radial piston type can be used in addition to the vane type.

(Embodiment 2) FIG. 10 is a hydraulic circuit diagram of a shift control device according to another embodiment of the present invention. FIG. 10 shows a portion corresponding to FIG. 2 in Embodiment 1. I have.

In this case, the hydraulic motor 30 is a variable displacement reversible hydraulic motor in the first embodiment, but is a fixed displacement reversible hydraulic motor.
Is provided between a connection shaft 32a connected to the hydraulic motor 30 and a connection shaft 32b connected to the hydraulic motor 30. The continuously variable transmission 91 has a transmission ratio that is controlled by a signal from the control unit 70. Controlled.

FIG. 11 is a sectional view showing a continuously variable transmission 91. A connecting shaft 32b connected to the rotor of the hydraulic motor 30 is rotatably mounted on the casing 92.
A connection shaft 32a connected to the rotor of the hydraulic pump 33 is rotatably mounted. A cone 93 is fixed to one connection shaft 32b, and a cone 94 is fixed to the other connection shaft 32a.
Are slidably mounted in the axial direction. The generatrix formed by the outer peripheral surfaces of the respective cones 93 and 94 is parallel, and a spring force is applied to one of the cones 94 toward the tip of the connection shaft 32a by a compression coil spring 95, so that a preload is applied. Has been given.

A feed screw shaft 96 is arranged between the two cones 93 and 94 in parallel with a parallel line formed by the generatrix. The feed screw shaft 96 is rotatably mounted on the casing 92 and is rotated by an electric motor 97. It is designed to be driven. A sleeve 98 is screwed to the feed screw shaft 96, and the sleeve 98 is reciprocally movable in the axial direction by an electric motor 97. Ball 9 in sleeve 98
9a and 99b are rotatably supported, and the ball 99
a is in contact with the outer peripheral surface of the cone 94, and the ball 99 b is in contact with the outer peripheral surface of the cone 93.

Therefore, when the feed screw shaft 96 is driven to rotate by the electric motor 97, the sleeve 98 moves in the axial direction and the contact position between the balls 99a, 99b and the cones 93, 94 changes. Each contact portion is pressed by a spring 95 with a strength required for power transmission, and the gear ratio between both connecting shafts 32a and 32b can be changed according to a change in the contact position.

The rotation speed of the connecting shaft 32a is set to N1,
b is N2 and the speed ratio of the continuously variable transmission 91 is ia
If (= N2 / N1), the above equation (3) becomes the following equation (3b) due to the balance in the connecting shaft 32a.

Ps × Dm = Pp × Dp × ia (3b) By transforming this equation, the primary pressure is expressed by the following equation (7).

Pp = Ps × Dm / Dp / ia (7) As can be understood from the equation (7), by controlling the gear ratio ia, both the hydraulic motor 30 and the hydraulic pump 33 are of the fixed displacement type. The same effect as in the first embodiment can be obtained.

Generally, a fixed displacement hydraulic pump and a hydraulic motor are more efficient than a variable displacement type, so that the consumption flow rate can be reduced and the oil pump 27 can be made more compact. In addition, the continuously variable transmission 91 transmits the torque even when the shaft is not rotating while transmitting torque.
And has a feature that the speed can be changed by the relative rotation of the balls 99a and 99b provided in the hydraulic pump, and effectively functions for transmitting power between the hydraulic pump and the hydraulic motor. For example, when the gear ratio is constant, both connecting shafts 32a and 32b are stopped, and in a normal continuously variable transmission such as a belt type or a toroidal type, the shift becomes extremely slow. And the hydraulic response is impaired. On the other hand, by using the continuously variable transmission 91 shown in FIG. 11, a shift response independent of the rotation speed of the input / output shaft is obtained, so that the traveling performance is not impaired.

(Embodiment 3) FIG. 12 is a hydraulic circuit diagram of a transmission control device according to another embodiment of the present invention. In this case, an oil pump 2 as a main hydraulic pump is used.
Reference numeral 7a is driven by an electric motor 101, and is regulated to a constant pressure by a pressure regulating valve 29a to discharge a line pressure to a line pressure passage 28. Since the oil pump 27a is driven by the electric motor 101, the pressure fluctuation of the line pressure is smaller than in the case of driving the engine.
“a” regulates pressure by a built-in spring and does not perform proportional control as in the line pressure regulating valve 29 described above.

In the line pressure passage 28, the accumulator 1
02 is connected, and accumulates excess hydraulic oil and discharges the hydraulic oil to the line pressure passage 28 during high-speed operation. Therefore, the electric motor 101 for driving the oil pump 27a can be operated only when necessary. That is, the electric motor 101 operates when the detected value of the hydraulic pressure sensor 103 becomes equal to or less than the set value, and stops the rotation when the detected value is equal to or more than the set value.

The line pressure passage 28 is connected to the first reversible hydraulic motor 3
0b is connected to a first port 31a, and a second port 31b of the reversible hydraulic motor 30b is connected to a guide oil passage 38 connected to an oil pan 36 as a hydraulic oil storage. Therefore, the line pressure is set to the reversible hydraulic motor 30.
b can generate torque.

The reversible hydraulic motor 30b is connected to a variable displacement reversible hydraulic pump 33b by a connecting shaft 32c, and can drive the hydraulic pump 33b by the torque generated by the hydraulic motor 30b. A primary pressure passage 35 is connected to the first port 34a of the hydraulic pump 33b, and a guide oil passage 38 is connected to the second port 34b of the hydraulic pump 33b.
Is connected. Therefore, the primary pressure can be generated by driving the hydraulic pump 33b by the hydraulic motor 30b.

The line pressure passage 28 is connected to the second reversible hydraulic motor 3
0c is connected to a first port 31a, and a second port 31b of the reversible hydraulic motor 30c is connected to a guide oil passage 38. Therefore, the line pressure can generate torque in the reversible hydraulic motor 30c.

The reversible hydraulic motor 30c is connected to a variable displacement reversible hydraulic pump 33c by a connecting shaft 32d, and the hydraulic pump 33c can be driven by the torque generated by the hydraulic motor 30c. A secondary oil passage 28a communicating with the secondary oil chamber 26 is connected to a first port 34a of the hydraulic pump 33c, and a guide oil passage 38 is connected to a second port 34b of the hydraulic pump 33c.
Therefore, the secondary pressure can be generated by driving the hydraulic pump 33c by the hydraulic motor 30c.

In the transmission control device shown in FIG. 12, the respective variable displacement reversible hydraulic pumps 33b and 33c and the electric motor 1 are controlled by a signal from the control unit 70.
01 operation is controlled, and the detection signal of the oil pressure sensor 103 is sent to the control unit 70.

In the case shown in FIG. 12, a variable displacement mechanism is incorporated in the hydraulic pumps 33b and 33c, which is different from the above-described embodiments.
p and the secondary pressure Ps are represented by the following equations (8) and (9), where PL is the line pressure.

Pp = Dm1 / Dp1 × PL (8) Ps = Dm2 / Dp2 × PL (9) Here, assuming that the pump elements (Dp1, Dp2) are variable in capacity,
It can be seen that a high pressure can be obtained by reducing the capacity.
Therefore, even if the discharge pressure of the oil pump 27a, which is the main hydraulic pump, is low, a high pressure can be generated to operate the pulley.

In this case, if the discharge pressure of the oil pump 27a is set to be equal to the operating pressure of the clutch or the torque converter, the configuration of the hydraulic circuit for operating these can be simplified. That is, in the case shown in FIG.
The line pressure supplied to the secondary oil chamber 26 is regulated by the line pressure regulating valve 29, and the clutch pressure supplied to the clutch or the brake is regulated by the clutch pressure regulating valve 4.
It is necessary to reduce the line pressure by 2 to adjust the pressure,
In the case shown in FIG. 12, if the clutch pressure is generated by the oil pump 27a, the oil pump 27
a can be reduced.

Further, since the line pressure can be kept constant, the accumulator 102 can be installed in the line pressure passage 28. Since the hydraulic oil amount is determined by the product of the pressure receiving area and the operating stroke in the clutch cylinder, pulley driving cylinder, and the like, which are operating elements of the CVT, if the volume required for the accumulator 102 is accumulated, the oil pump 27a The oil amount required for the operation speed can be supplied without increasing the discharge amount.

The connecting shafts 32c and 32d shown in FIG.
0, the variable displacement reversible hydraulic pumps 33b, 33c may be fixed displacement reversible hydraulic pumps. The variable displacement reversible hydraulic pumps 33b, 33c may be fixed. The displacement type reversible hydraulic motors 30b and 30c may be variable displacement type reversible motors. Similarly, the variable displacement reversible hydraulic motor 30 shown in FIG. 2 may be a fixed displacement type, and the reversible hydraulic pump 33 may be a variable displacement type.

In any of the embodiments, the oil pumps 27 and 27a as the main hydraulic pumps may be driven by an engine or an electric motor.

The present invention is not limited to the above-described embodiment, and it goes without saying that various changes can be made without departing from the scope of the present invention. For example, the drive system of the belt-type continuously variable transmission is not limited to the case shown in FIG. 1, and the present invention can be applied to various types such as a type having no torque converter 2.

[0096]

According to the present invention, when shifting up by narrowing the groove width of the primary pulley, the reversible hydraulic motor is driven by the line pressure, and the reversible hydraulic pump is driven by the reversible motor, whereby the hydraulic oil is driven. Is supplied to the primary oil chamber. On the other hand, when shifting down by widening the groove width of the primary pulley, the reversible hydraulic motor is driven through a reversible hydraulic pump driven by the hydraulic oil discharged from the primary oil chamber, and the hydraulic oil discharged therefrom is Can be supplied to the secondary oil chamber. As a result, the power consumption efficiency can be improved by reducing the energy consumed by the oil pump, and the energy required for the shift control can be reduced.

According to the present invention, when hydraulic oil is supplied to the primary oil chamber for upshifting, the first reversible hydraulic pump is driven via the first reversible hydraulic motor driven by the line pressure. Hydraulic oil is supplied to the primary oil chamber, and the hydraulic oil discharged from the secondary oil chamber drives the second reversible hydraulic motor via the second reversible hydraulic pump. Return to pressure path. On the other hand, when downshifting, the first reversible hydraulic motor is driven via the first reversible hydraulic pump driven by the hydraulic oil discharged from the primary oil chamber, and the hydraulic oil discharged therefrom is supplied to the line. Discharge into the pressure path. The second reversible hydraulic pump is driven via the second reversible motor by the hydraulic oil discharged to the line pressure path, and the hydraulic oil is supplied to the secondary oil chamber. As a result, the power consumption efficiency can be improved by reducing the energy consumed by the oil pump, and the energy required for the shift control can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an example of a drive system of a belt-type continuously variable transmission.

FIG. 2 is a hydraulic circuit diagram of a shift control device for a continuously variable transmission according to an embodiment of the present invention.

FIG. 3 is a sectional view showing the reversible hydraulic motor and the reversible hydraulic pump shown in FIG. 2;

FIG. 4 is a sectional view showing the reversible hydraulic pump in a direction along a line IV-IV in FIG. 3;

FIG. 5 is a sectional view of the hydraulic motor taken along a line VV in FIG. 3;

FIG. 6 is a sectional view showing a modified example of the reversible hydraulic pump and the reversible hydraulic motor.

FIG. 7 is a block diagram showing a control unit for performing shift control.

FIG. 8 is a diagram showing a displacement amount of a pulley when a shift operation is performed.

FIG. 9 is a characteristic diagram showing a flow rate of hydraulic oil when the continuously variable transmission is downshifted.

FIG. 10 is a hydraulic circuit diagram of a shift control device according to another embodiment of the present invention.

FIG. 11 is a sectional view showing the continuously variable transmission shown in FIG.

FIG. 12 is a hydraulic circuit diagram of a shift control device according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 13 Primary shaft 14 Secondary shaft 15 Primary pulley 16 Secondary pulley 17 Belt 22 Primary cylinder 23 Primary oil chamber 24 Plunger 25 Secondary cylinder 26 Secondary oil chamber 27, 27a Oil pump 28 Line pressure path 29 Line pressure regulating valve 30 Variable capacity reversible hydraulic motor 31a first port 31b second port 32 connecting shaft 33 reversible hydraulic pump 34a first port 34b second port 35 primary pressure path 36 oil pan (hydraulic oil storage) 38 guide oil path 70 control unit (shift control) means)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F16H 59:40 F16H 59:40 59:42 59:42 59:70 59:70 59:72 59:72 63 : 06 63:06 F term (reference) 3J050 AA02 BA03 BB13 CE09 DA02 3J051 AA03 BA02 BB01 BD01 BE05 CA03 CB04 DA09 ED18 FA02 3J552 MA07 MA12 MA26 NA01 NB01 PA59 QA30B QA30C QA33C SA36 SA52 SB02 VA18Z VA32ZVA37ZVZZZ

Claims (6)

[Claims] 1. A pulley having a variable pulley groove width mounted on a primary shaft and a secondary pulley having a variable pulley groove width mounted on a secondary shaft and having a belt stretched between the primary pulley and the primary pulley. A shift control device for a stepped transmission, comprising: a primary cylinder provided on the primary pulley and having a primary oil chamber; a secondary cylinder provided on the secondary pulley and having a secondary oil chamber; A reversible hydraulic motor having a first port communicating with a line pressure path for supplying hydraulic oil of a line pressure from the first port and a second port communicating with an oil path connected to the hydraulic oil accommodating section; A first port communicating with the primary pressure passage connected to the hydraulic fluid storage portion and a first port communicating with the hydraulic pressure storage portion A reversible hydraulic pump having a second port connected to the reversible hydraulic motor, a variable displacement mechanism for changing an amount of hydraulic oil flowing through the reversible hydraulic motor or the reversible hydraulic pump, and operation of the variable displacement mechanism Transmission control means for controlling the speed change of the continuously variable transmission. 2. A pulley having a variable pulley groove width mounted on a primary shaft and a secondary pulley having a variable pulley groove width mounted on a secondary shaft and having a belt stretched between said primary pulleys. A shift control device for a step transmission, comprising: a primary cylinder provided on the primary pulley and having a primary oil chamber; a secondary cylinder provided on the secondary pulley and having a secondary oil chamber; and a line pressure from a hydraulic pressure source. A first reversible hydraulic motor having a first port communicating with a line pressure path for guiding hydraulic oil and a second port communicating with an oil path connected to the hydraulic oil storage unit; and connecting to the primary oil chamber. A first port communicating with the primary pressure passage and a second port communicating with an oil passage connected to the hydraulic oil storage portion. A first reversible hydraulic pump connected to the first reversible hydraulic motor, and a second port connected to a first port communicating with the line pressure passage and an oil passage connected to the hydraulic oil storage unit. A second reversible hydraulic motor having a first port, a first port communicating with a secondary pressure passage connected to the secondary oil chamber, and a second port communicating with an oil passage connected to the hydraulic oil storage unit. A second reversible hydraulic pump connected to the second reversible hydraulic motor, and a first variable for changing an amount of hydraulic oil flowing through the first reversible hydraulic motor or the first reversible hydraulic pump. A displacement mechanism, a second variable displacement mechanism that changes an amount of hydraulic oil flowing through the second reversible hydraulic motor or the second reversible hydraulic pump, and a shift control unit that controls operation of each of the variable displacement mechanisms. With The shift control device for a continuously variable transmission according to claim Rukoto. 3. The shift control device for a continuously variable transmission according to claim 1, wherein the reversible hydraulic motor or the reversible hydraulic pump is a variable displacement reversible hydraulic motor or a variable displacement reversible hydraulic pump incorporating a variable displacement mechanism. A shift control device for a continuously variable transmission, characterized in that: 4. The shift control device for a continuously variable transmission according to claim 1, wherein the reversible hydraulic motor and the reversible hydraulic pump are a fixed displacement hydraulic motor and a hydraulic pump, respectively. A shift control device for a continuously variable transmission, wherein a pump is connected via a continuously variable transmission, and the continuously variable transmission is the variable displacement mechanism. 5. The continuously variable transmission according to claim 1, wherein the hydraulic source is an oil pump driven by an engine. 5. The continuously variable transmission according to claim 1, wherein the hydraulic pressure source is an oil pump driven by an engine. Transmission control device. 6. The shift control device for a continuously variable transmission according to claim 1, wherein the hydraulic source is an oil pump driven by an electric motor and a pressure accumulator that stores hydraulic oil. A shift control device for a continuously variable transmission, comprising: