JPH0262464A - Line pressure control device for belt type continuously variable transmission - Google Patents

Abstract

PURPOSE:To set line pressure without any excess or shortage by detecting turbine torque in a torque converter and a gear ratio in a belt type continuously variable transmission for controlling the line pressure. CONSTITUTION:A control unit 78 outpus a duty ratio to the first solenoid 51 for achieving line pressure P determined as the function of a value obtainable from the input torque (turbine torque TT) of a torque converter multiplied by a gear ratio HM. In this case, the gear ratio HM is defined as a ratio of a primary shaft speed NP to a secondary shaft speed NS in a continuously variable transmission. The turbine torque TT is obtainable from engine output torque TE from an engine multiplied by a torque ratio HT. The engine torque TE is a value defined from a relationship between an engine speed NE and a throttle opening TVO. According to the aforesaid construction, it is possible to set up line pressure in good response to belt transmission torque and free from excess or shortage.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a line pressure control device for a belt type continuously variable transmission in which engine output is transmitted via a torque converter.

[Prior Art] Conventionally, line pressure control devices for belt-type continuously variable transmissions configured to transmit engine output obtained through a fluid coupling to wheels at a predetermined gear ratio have been used, for example. A line pressure control method for a belt-type continuously variable transmission is known, which is disclosed in Japanese Patent Application Laid-Open No. 58-88252.

In addition, in this conventional technology, the engine torque is calculated from the engine operating conditions based on the engine output torque characteristics stored in the microcomputer, and the line pressure is set according to that value and the reduction ratio. The purpose is to improve power transmission efficiency.

[Problems to be Solved by the Invention] However, when applying this conventional technology to a line pressure control device for a belt-type continuously variable transmission in which engine output is transmitted via a torque converter, the following problems occur. This will cause problems as explained below.

In other words, when the torque output from the engine is transmitted to the belt type continuously variable transmission via the torque converter,
This torque converter changes the torque ratio transmitted to the continuously variable transmission according to the speed ratio. Specifically, at a predetermined speed ratio, a region in which the torque is increased is defined. As a result, when the line pressure for controlling the hydraulic pressure supplied to the secondary pulley chamber is defined based only on the engine torque and gear ratio, as described above, it is actually transmitted to the continuously variable transmission. The torque will differ from the torque output from the engine in the region increased by the torque converter.

Therefore, the line pressure that controls the hydraulic pressure supplied to the secondary booby chamber is not properly regulated according to the belt's transmission torque, and there is a risk of slippage occurring between the secondary booby and the belt. This causes problems in terms of pump loss, belt durability, etc.

In addition, in order to solve this problem, if the line pressure is controlled according to the transmitted torque when the torque converter's torque ratio takes the maximum value, line pressure is unnecessary in the region where the torque increasing effect of the torque converter is small. This causes problems in terms of pump loss and drive loss due to excessive frictional force with the boulide belt.

This invention was made in view of the above-mentioned problems, and an object of the invention is to provide a belt-type continuously variable transmission that can accurately respond to belt transmission torque and set line pressure without excess or deficiency. An object of the present invention is to provide a line pressure control device.

[Means for Solving the Problems] In order to solve the above-mentioned problems and achieve the purpose, the line pressure control device for a belt type continuously variable transmission according to the present invention has the following features:
A line pressure control device for a belt-type continuously variable transmission in which engine output is transmitted via a torque converter, comprising: a first detection means for detecting turbine torque in the torque converter; and a speed change in the belt-type continuously variable transmission. It is characterized by comprising a second detection means for detecting the ratio, and a control means for controlling the line pressure based on the detection results of the first and second detection means.

[Function] In the line pressure control device for the belt type continuously variable transmission configured as described above, the line pressure is set based on the turbine torque in the torque converter and the gear ratio in the belt type continuously variable transmission. is being done. As a result, the line pressure that controls the hydraulic pressure supplied to the secondary booby chamber is properly regulated according to the transmission torque of the belt, preventing slippage between the secondary booby and the belt, reducing pump loss, This will improve the durability of the belt.

[Embodiment] Hereinafter, an embodiment of a line pressure control device for a belt type continuously variable transmission according to the present invention will be described in detail with reference to the accompanying drawings.

First, FIG. 1 shows a skeleton diagram showing the overall configuration of the continuously variable transmission Z, and FIG. 2 shows the hydraulic circuit Q of the continuously variable transmission 2 shown in FIG. There is. For convenience of explanation, the overall configuration of the continuously variable transmission 2 will first be briefly described with reference to FIG. 1, and then with reference to FIG.
The configuration of a hydraulic circuit Q equipped with a line pressure control device, which is the gist of the present invention, will be explained.

This continuously variable transmission Z is a continuously variable transmission for a front wheel drive vehicle, and includes a torque converter B connected to the output shaft 1 of an engine A, a forward/reverse switching mechanism C, and a belt transmission. It basically includes a mechanism, a reduction mechanism E, and a differential mechanism F.

[Torque converter B] The torque converter B includes a pump impeller 3 that is 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 this pump impeller 3. Pump cover 7 so that it faces
A turbine runner 4 is rotatably provided in a converter chamber 7a formed inside the pump impeller 3, and a stator 5 is interposed between the pump impeller 3 and the turbine runner 4 to increase torque. There is. Further, the turbine runner 4 is connected to a carrier 15, which is an input member of a forward/reverse switching mechanism C, which will be described later, via the turbine shaft 2, and a stator 5.
are connected to a transmission case 19 via a one-way clutch 8 and a stator shaft 9, respectively.

Furthermore, between the turbine runner 4 and the pump cover 7,
A lock-up piston 6 is arranged. 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 the pump cover 7, which is in a lock-up state. This pump cover 7
The converter state is selectively realized away from the converter state. 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 side through the fluid. transmitted to.

[Forward/forward switching mechanism C] The forward/reverse switching mechanism C has 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 a reverse state in which the rotation is transmitted in a reverse state to the belt transmission mechanism. In this embodiment, the forward/reverse switching mechanism C is constructed of a double-binion planetary gear unit. That is, the carrier 15 spline-coupled to the turbine shaft 2 includes a first pinion gear 13 that meshes with the sun gear 12;
A second pinion gear 14 that meshes with the ring gear 11 is attached. 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 fix the ring gear 11 to the transmission case 19. A brake 17 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 allowed to rotate relative to the transmission case 19, so that the turbine shaft 2 The rotation is directly output from the sun gear 12 to the primary shaft 22 side as a rotation in the same direction (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 output from the sun gear 12 to the primary shaft 22 side (reverse traveling state).

That is, in this forward/reverse switching mechanism C, the clutch 16
By selectively operating the brake 17 and the brake 17, switching between forward and backward travel is executed.

[Belt transmission mechanism D] The belt transmission mechanism includes a primary pulley 21 (described later) coaxially arranged on the rear side of the forward/reverse switching mechanism C described above.
A belt 20 is stretched between the primary pulley 21 and a secondary pulley 31, which will be described later, and which is spaced apart from the primary pulley 21 in a direction parallel to the primary pulley 21.

(Primary pulley 21) This primary pulley 21 is arranged coaxially with the above-mentioned turbine shaft 2, and one shaft end thereof is mounted on a primary shaft 22 spline-coupled to the sun gear 12 of the forward/reverse switching mechanism C. A fixed conical plate 23 having a predetermined diameter is provided integrally with the primary shaft 22, and a movable conical plate 24 is provided so as to be movable in the axial direction of the primary shaft 22. 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.

Furthermore, a cylindrical cylinder 25 is fixed to the outer surface 24a side of the movable conical plate 24. Furthermore, this cylinder 2
A piston 26 fixed to the primary shaft 22 side is fitted in an oil-tight manner on the inner peripheral surface side of the piston 2.
6, the cylinder 25 mentioned above, and the movable conical plate 24 constitute the primary chamber 27. Note that line pressure is introduced into this primary chamber 27 from a hydraulic circuit Q, which will be described later.

This primary pulley 21 is connected to the primary chamber 2
The effective diameter of the belt 20 is adjusted by moving the movable conical plate 24 in the axial direction by hydraulic pressure introduced into the movable conical plate 7 and increasing or decreasing the distance between the movable conical plate 24 and the fixed conical plate 23.

(Secondary pulley 31) This secondary pulley 31 basically has the same configuration as the primary pulley 21 described above,
A fixed conical plate 33 is mounted integrally with the secondary shaft 32 on a secondary shaft 32 arranged parallel to and apart from the primary shaft 22, and a movable conical plate 34 is movable on the secondary shaft 32. They are configured by providing them respectively.

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, define a belt receiving groove 31a having a substantially V-shaped cross section.

Furthermore, a substantially cut cylindrical cylinder 35 is coaxially fixed to the outer surface 34b of the movable conical plate 34. Further, a piston 36 fixed to the secondary shaft 32 is fitted into the inner circumferential surface of the cylinder 35 in an oil-tight manner at a portion closer to the axis thereof. This piston 36 and cylinder 35
A secondary chamber 37 is constituted by the movable conical plate 34. Line pressure is introduced into this secondary chamber 37 from the hydraulic circuit Q, similarly to the primary pulley 21 side.

Similarly to the primary pulley 21, the effective diameter of the secondary pulley 31 with respect to the belt 20 is adjusted by moving its movable conical plate 34 toward and away from the fixed conical plate 33.

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.

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

[Operation] The operation of this continuously variable transmission 2 will be briefly explained below.

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 rotation direction set to the forward direction or the reverse direction.

In a belt transmission mechanism, when the effective diameter of the primary pulley 21 is adjusted by introducing or discharging hydraulic oil into the primary chamber 27, this primary pulley 2
1, the effective diameter of the secondary pulley 31, which is interlocked and connected via the belt 20, is adjusted in accordance with the secondary pulley 31. The ratio between the effective diameter of the primary pulley 21 and the effective diameter of the secondary pulley 31 determines the gear ratio between the primary shaft 22 and the secondary shaft 32.

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).

Hydraulic circuit Q shown in FIG. 2 includes the lock-up piston 6 of the torque converter B in the above-mentioned continuously variable transmission Z,
It is provided to control the operation of the clutch 16 and brake 17 of the forward/reverse switching mechanism C, and the primary pulley 21 and secondary pulley 31 of the belt transmission mechanism, and includes an oil pump 40 driven by the engine A. . Here, the oil pump 40 is defined as a pressure source that provides a common (same) control source pressure supplied to the primary chamber 27, secondary chamber 37, etc. as control elements.

The hydraulic oil discharged from this oil pump 4o is first
After the pressure is adjusted to a predetermined level in the line pressure regulating valve 41, it is transferred to the secondary chamber 37 of the secondary pulley 31 via a line 101, and to the primary chamber 37 of the primary pulley 21 via a line 102 branched from this line 101. are supplied to the chambers 27, respectively.

Line pressure control in the line pressure regulating valve 41 is performed by controlling the pilot pressure introduced into the pilot chamber 41a. That is, the line pressure regulating valve 41 includes a spool 41b and a spring 41c that biases the spool 41b.
It also includes a pressure regulating boat 41d to which oil discharged from the oil pump 40 is guided, and a train boat 41e communicating with the suction side of the oil pump 40.

Further, hydraulic oil, which is branched from the line 102 and reduced to a predetermined pressure by the reducing valve 42, is introduced into the pilot chamber 41a via the line 103 as pilot pressure. Therefore, this line pressure regulating valve 41 is
The spool 41b is connected to the hydraulic pressure in the line 101 applied to one end thereof and the spring 41 applied to the other end.
Depending on the balance between the biasing force of c and the resultant force of the pilot pressure introduced into the pilot chamber 41a, the drain boat 41e is connected to or disconnected from the pressure regulating boat 41d by sliding, depending on the pilot pressure. It generates line pressure.

Further, the pilot pressure for controlling this line pressure is adjusted by electrically controlling the duty ratio of the first solenoid valve 51 provided in the line 103. The control details of the first electromagnetic solenoid valve 51 will be described later.

Further, the line 102 is provided with a gear ratio control valve 43 that operates in response to pilot pressure.

Control of the gear ratio of the continuously variable transmission Z is performed by controlling the supply and discharge of hydraulic oil to the primary chamber 27 of the primary pulley 21 using the gear ratio control valve 43.

That is, the gear ratio control valve 43 includes a spool 43a that is always pressed toward the blade side by a spring 43b, and a line pressure boat 43c that communicates with the line 102.
A drain boat 43d, a pilot boat 43e that opens into a pilot chamber 43f formed on the opposite end side of the spring 43b, and a reverse boat that opens on the spring 43b side and into which line pressure is introduced via a shift valve 45, which will be described later. The boat has a weight of 43g.

When moving forward (when the shift valve 45 is in either the D or 2.1 shift position), the reverse boat 43g is drained via the shift valve 45, and the spool 43a is connected to the pilot chamber 43f. It becomes possible to slide in the axial direction in response to pilot pressure introduced into the shaft. The line pressure boat 43c and the drain boat 43d are selectively communicated with the primary chamber 27 by the spool 43a, thereby controlling the supply and discharge of hydraulic oil to the primary chamber 27, that is, controlling the gear ratio. become.

On the other hand, when moving backward, line pressure is introduced from the reverse boat 43g, and the spool 43a receives this line pressure and is fixed in a state where it is fully pressed to the right in the figure.

Therefore, regardless of the pilot pressure, the line pressure boat 43c and the drain boat 43d are always in communication with each other, and the gear ratio is kept fixed at the maximum gear ratio.

In this embodiment, two pilot pressure supply systems to the speed ratio control valve 43 are provided, and these systems are set to be selectively used by a switching valve 44, which will be described later. That is, the switching valve 44 includes a spool 44a and a spring 44b that biases the spool 44a toward one side. In addition, this switching valve 44 connects a pilot boat 44C, which is opened at the end on the side opposite to the spring 44b, to a line 105 branched from the line 103, and connects a pilot boat 44C, which is depressurized by the reducing valve 42, to one end of the spool 44a. I'm trying to put pressure on it.

Further, in the middle part of the switching valve 44, a first pilot pressure introduction boat 44d communicating with the line 105, a second pilot pressure introduction boat 44e communicating with a pitot pressure generating means (not shown), and a gear ratio control A pilot pressure supply boat 44f communicating with the pilot boat 43e of the valve 43 via a line 104 is adjacent to the pilot boat 43e.

A second electromagnetic solenoid valve 52 is provided in the line 105 communicating with the first pilot pressure introduction boat 44d,
Depending on the operating state of the second electromagnetic solenoid valve 52, the oil pressure regulated by the second electromagnetic solenoid valve 52 and the pitot pressure generated in accordance with the rotational speed of the engine are selectively controlled by the gear ratio control valve 43. The pressure is supplied to the pilot chamber 43f as a pilot pressure to perform predetermined gear ratio control.

The details of the speed ratio control using the second electromagnetic solenoid valve 52 and the switching valve 44 will be described later.

On the other hand, the hydraulic oil whose pressure is regulated by the line pressure regulating valve 41 is
It is introduced into the boat 44a of the switching valve 44 via the line 106. The hydraulic oil supplied to the boat 44a is supplied to the brake chamber 62 of the brake 17 via line 107 when the reverse gear is set, and to the clutch 16 via the line 108 when the forward gear is set. They are supplied to the clutch chamber 61, respectively, to put the forward/reverse switching mechanism C into the reverse or forward operating state.

In this embodiment, line 107 and line 1
One accumulator 18 is provided between the clutch 16 and the brake 17, and the engagement shock of both the clutch 16 and the brake 17 is effectively alleviated by this one accumulator 18.

Further, the pressure of the hydraulic oil regulated by the line pressure regulating valve 41 is regulated to a predetermined clutch pressure by the clutch pressure regulating valve 46, and then
Lockup control valve 47 via line 109
will be introduced in The hydraulic oil introduced into the lock-up control valve 47 is controlled on the lock-up engagement side (LOC) by controlling the pilot pressure of the lock-up control valve 47 with the third electromagnetic solenoid valve 53.
K) or is selectively supplied to the lockup release side (UNLOCK).

Further, in FIG. 2, reference numeral 48 indicates a relief valve.

In the hydraulic circuit Q configured as described above, the following is performed.
A method of controlling the gear ratio control valve 43 will be described in detail.

First, the control range of the second electromagnetic solenoid valve 52 and the switching valve 4
4, this second electromagnetic solenoid valve 52 has a duty ratio that changes from 0 to 100%, as shown in FIG. ) can be changed within the range of 0-PI.

On the other hand, in the switching valve 44, the spool 44a moves in the axial direction in accordance with the hydraulic pressure applied to the pilot boat 44c, thereby selectively switching between the first pilot pressure introduction boat 44d and the second pilot pressure introduction boat 44e. It is configured to communicate with the pilot pressure supply boat 44f. In this embodiment, in particular, the relative positions of the first and second pilot pressure introduction boats 44d and 44e and the pilot pressure supply boat 44f are determined based on the magnitude of the pilot pressure, that is, the duty of the second electromagnetic solenoid valve 52. The following settings are made according to the ratio.

That is, the duty ratio of the second electromagnetic solenoid valve 52 increases,
-D,%, i.e. when the pilot pressure is P0
~P2, the spool 44a is in the second
It is located between the positions shown in the upper and lower parts of the figure, and the first pilot pressure introduction boat 44d communicates with the pilot pressure supply boat 44f, while the second pilot pressure introduction boat 44e is in a closed state. .

Further, the duty ratio of the second electromagnetic solenoid valve 52 is O-
When the pilot pressure is within the range of D and %, that is, when the pilot pressure is within the range of P0 to P1, the spool 44a moves fully to the right as shown in the upper part of FIG. 2, and the first pilot pressure introduction boat 44d is closed, while the second pilot pressure introduction boat 44e is closed to the pilot pressure supply boat 44.
The positions of the first and second pilot pressure introduction boats 44d, 44e and the pilot pressure supply boat 44f are adjusted so that they communicate with the pilot pressure supply boat 44f, and the duty ratio of the second electromagnetic solenoid valve 52,
That is, it is set relatively according to the oil pressure in the line 105.

Incidentally, the speed change control by this second electromagnetic solenoid valve 52 is as follows:
As shown in FIG. 4, the vehicle speed (i.e., the rotational speed of the secondary pulley 31 and the throttle opening) are set in advance for each shift position in accordance with the current driving state determined from the target primary boost rotation speed map. The target gear ratio is calculated from the deviation between the corresponding target primary pulley rotation speed and the actual primary pulley rotation speed, and in order to achieve this, the pilot of the gear ratio control valve 43 is controlled by the second electromagnetic solenoid valve 52. Adjust the pressure and open the primary chamber 27
This is done by controlling the supply and discharge of hydraulic oil to and from the

With this configuration, even when the electric circuit of the second electromagnetic solenoid valve 52 is disconnected, the gear ratio can be controlled, and the temperature of the hydraulic oil is low, so that the duty control of the second electromagnetic solenoid valve 52 can be performed. Even when there is a risk that the gear ratio may become unstable, stable gear ratio control can be performed.

Used in the hydraulic circuit Q configured as described above,
The control operation of the first electromagnetic solenoid valve 51, which is a feature of the present invention, will be described in detail below. The configurations of the second and third electromagnetic solenoid valves 52 and 53 are the same as the configuration of the first electromagnetic solenoid valve 51 described below.

The first electromagnetic solenoid valve 51 includes a valve housing 70, as shown in FIG. A flow path 71 is formed in this valve housing 70, and this flow path 71
One end is connected to the terminal end of a branch line 72 branched from the line 105, and the other end is connected to the starting end of a return line 74 leading to the reservoir tank 73.

Inside the valve housing 70, there is a
A plunger 75 serving as a valve body is disposed so as to be able to reciprocate between a closed position where it is closed and an open position where it is pulled in from the flow path 71 and opened. The plunger 75 is always subjected to an elastic biasing force biased toward the closed position by the coil spring 76. On the other hand, an electromagnetic coil 77 surrounds the middle part of the plunger 75.
surrounded by. The electromagnetic coil 77 applies an electromagnetic urging force to the plunger 75 when energized. In the electromagnetic solenoid valve 51 configured as described above, the duty ratio is the time required for one cycle. (T
It is defined from the ratio (TON/T CYCLK) of the energization time (TON) per cycle (CYCLE).

As shown in FIG. 6, a control unit 78 is connected to each electromagnetic solenoid valve 51, 52.53, and each electromagnetic solenoid valve 51, 52.53 is controlled by a control element. The drive is controlled to control the

Next, referring to FIG. 6, the electric control circuit R of the hydraulic circuit Q
I will explain about it.

That is, this electric control circuit R has a control unit 78 that performs duty control on the first to third electromagnetic solenoid valves 51, 52, and 53, respectively. This control unit 78 has shift positions (D, 1, 2, R,
When the shift position signal a from the shift position sensor 82 that detects the rotation speed N, P) and the primary pulley rotation speed signal from the primary rotation speed sensor 83 that detects the rotation speed Np of the primary shaft 22, the rotation speed of the secondary shaft 32 is determined. NS (
Secondary rotation speed sensor 84 that detects vehicle speed)
, a throttle opening signal d from a throttle opening sensor 85 that detects the throttle opening TVO of engine A, and a rotational speed sensor 86 that detects the engine rotation speed N8 of engine a. and the rotational speed signal e of the turbine shaft 2 in the torque converter B.
A turbine rotation speed signal f from a turbine rotation speed sensor 87 that detects the rotation speed NT of the engine is input.

Based on these input signals a, b, c, d, e, and f, the control unit 78 is configured to calculate the duty ratios of the first to third electromagnetic solenoids 51, 52, and 53.

That is, with respect to the first electromagnetic solenoid valve 51, this control unit 78 controls the input torque from the torque converter B (in other words, the turbine torque TT
) is set to output to the first electromagnetic solenoid 51 a duty ratio that achieves a defined line pressure P as a function of the value multiplied by the gear ratio H1.

P=f (Tcho XHH) Here, the gear ratio H1 is defined as the ratio of the rotation speed Np of the primary shaft 22 to the rotation speed Ns of the secondary shaft 32 in the continuously variable transmission Z (Ho '' Ns / Np). The turbine torque 91 is obtained by multiplying the engine output torque Tt from the engine A by the torque ratio HT.

Further, the engine torque TK is a value defined from the relationship between the engine speed NE and the throttle opening degree TV○.

Therefore, the line pressure is finally defined as P=f (TE XHT XHH).

Next, the control procedure for the first electromagnetic solenoid valve 51 in the control unit 78 will be specifically explained with reference to the flowchart shown in FIG.

First, in step SIO, the shift position sensor 82
The shift position is read based on the detection signal a from .

Then, in step S12, the shift position read in step S10 is determined, and the parking position (P) is determined.
Alternatively, if it is determined that the vehicle is in the neutral position (N), which is a non-travel position, the input torque TT to the continuously variable transmission 2 is set to zero in step S14.

On the other hand, if it is determined in step SL2 that the shift position is the reverse drive position (R) or the forward drive position (D, 1.2), the process advances to step S16, where the rotation speed sensor 86 The engine rotation speed N is read from the rotation speed signal e from the engine, and the throttle opening TVO is read from the throttle opening signal d from the throttle opening sensor 85. Then, in the subsequent step S18, based on the correlation shown in FIG. 8 from the engine speed NE and throttle opening TVO read in step S16,
Calculate the output torque T from engine A.

Further, in the subsequent step S20, the turbine shaft 2 of the torque converter B is detected from the turbine rotation speed sensor 87.
Based on the detection signal f, read the turbine rotation speed NT,
Defined as the output rotation speed of torque converter B. Then, in step S22, the speed ratio Hs in torque converter B is determined from the ratio between the turbine rotation speed NT read in step S20 and the engine rotation speed NK (that is, the human rotation speed for torque converter B) read in step S16. (=NT/NE) is calculated.

Then, in step S24, the torque ratio Hr is calculated from the speed ratio H3 read in step S22 based on the correlation shown in FIG.

As is clear from FIG. 9, the torque ratio H reaches its maximum value when the speed ratio Hs is zero, that is, when the vehicle is stopped.
2", and as the speed ratio Hs gradually increases from zero, it is gradually decreased from "2". Then, when the speed ratio Hs reaches approximately 0.8, the torque ratio HT is saturated to "1" and is set to be maintained at "1" thereafter.

In this way, the torque ratio H5 calculated in step S24
From this, the input torque T7 to the continuously variable transmission 2 is calculated in step S26. That is, this input torque TT is
It is calculated by multiplying the engine output torque T6 calculated in step S18 by the torque ratio Ha mentioned above. Note that, as described above in step S14, this input torque T7 is set to zero in the non-running state.

After that, in step S28, the primary rotation speed signal B from the primary rotation speed sensor 83 determines the rotation speed Np of the primary shaft 22 and the secondary rotation speed sensor 8.
The rotation speed N of the secondary shaft 32 is determined by the secondary rotation speed signal C from 4.

are loaded respectively. Then, in step S30, the primary axis 2 read in step S28 is
2 and the rotation speed Ng of the secondary shaft 32, the gear ratio H, (=N, /NP) is calculated.

On the other hand, after calculating the human torque TT and the gear ratio Ho in this way, in step S32, these input torques T
A target secondary pressure acting on the secondary chamber 37 is calculated from T and the gear ratio H8 based on the correlation shown in FIG. Then, in step S34, line pressure P for achieving this target secondary pressure is calculated, in step S36, a duty ratio that defines this line pressure P is calculated, and in step S38, control with this duty non-information is performed. The signal is output to the first electromagnetic solenoid valve 51, and the series of control operations is completed.

As described in detail above, in this embodiment, the input torque TT input to the continuously variable transmission Z is defined in consideration of the torque ratio HT in the torque converter B. As a result, the input torque TT, which is the basis for regulating the line pressure P, has a value that is more in line with the torque actually input to the continuously variable transmission 2. Therefore, according to this embodiment, the line pressure P that controls the hydraulic pressure supplied to the secondary pulley chamber 37 has a value that is properly defined according to the transmission torque of the belt 20, and This ensures that slippage is prevented between the
This will improve pump loss, belt durability, etc.

It goes without saying that this invention is not limited to the configuration of the one embodiment described above, and can be modified in various ways without departing from the gist of the invention.

[Effects of the Invention] As detailed above, the line pressure control device for a belt type continuously variable transmission according to the present invention controls the line pressure of a belt type continuously variable transmission to which engine output is transmitted via a torque converter. In the control device, a first detection means for detecting turbine torque in the torque converter, a second detection means for detecting a gear ratio in the belt type continuously variable transmission, and detection of the first and second detection means. Based on the results,
It is characterized by comprising a control means for controlling line pressure.

Therefore, according to the present invention, there is provided a line pressure control device for a belt-type continuously variable transmission that can accurately correspond to the belt transmission torque and set the line pressure without excess or deficiency.

[Brief explanation of the drawing]

Fig. 1 is a skeleton diagram schematically showing the configuration of a continuously variable transmission to which an embodiment of the line pressure control device for a belt type continuously variable transmission according to the present invention is applied; Fig. 2 is shown in Fig. 1. A circuit diagram showing the configuration of a hydraulic circuit connected to the continuously variable transmission: Fig. 3 is a diagram showing the correlation between the duty ratio and pilot pressure in the electromagnetic solenoid valve provided in the hydraulic circuit shown in Fig. 2; Figure 4 is a diagram showing the speed change characteristics of a continuously variable transmission; Figure 5 is a sectional view showing the configuration of the electromagnetic solenoid valve; Figure 6 is a wiring diagram showing the configuration of the electric control circuit of the hydraulic circuit; Figure 7 is a flow chart showing the control procedure in the control unit; Figure 8 is a line diagram showing the relationship between the output torque defined by engine speed and throttle opening; Figure 9 is a line diagram showing the relationship between speed ratio and torque ratio. FIG. 10 is a diagram showing the relationship between the target secondary pressure defined from the speed ratio and the human torque. In the diagram, A...engine, B...torque converter,
C... Forward/forward switching mechanism, D... Belt transmission mechanism, E
...Reduction mechanism, F...Differential mechanism, HH...Transmission ratio, H3...Speed ratio, H-Torque ratio, Nt...
Engine speed, NP...Primary shaft speed, Ns
...Secondary shaft rotation speed, Nr...Turbine rotation speed, P...Line pressure, Q...Hydraulic circuit, R...Electric control circuit, TE...Output torque, T7...Turbine Torque (input torque), z...Continuously variable transmission, 1...
Output shaft, 2... Turbine shaft, 3... Pump impeller, 4... Turbine runner, 5... Stator, 6...
・Lock-up piston, 7...Pump cover 7a
...Converter chamber, 8...One-way clutch, 9
... Stator shaft, 10... Lock-up chamber, 11.
...Ring gear, 12...Sun gear, 13...1st
Pinion gear, 14...Second pinion gear, 15...
・Carrier, 16...Clutch, 17...Brake, 18...Accumulator, 19...Mission case, 20...Belt, 21...Primary pulley, 21a...Belt receiving groove, 22 ...Primary axis,
23... Fixed conical plate, 24... Movable conical plate, 24a
...Outer surface, 25...Cylinder, 26...Piston, 27...Primary chamber, 31...Secondary pulley, 31a...Belt receiving groove, 32...Secondary shaft, 33...・Fixed conical plate, 34...Movable conical plate, 3
4a... Conical friction surface, 34b... Outer surface, 35.
...Cylinder, 36...Piston, 37...Secondary chamber, 40...Oil pump, 41...Line pressure regulating valve, 41a...Pilot chamber, 41b...Spool, 41c... Spring, 41d... Pressure regulating boat, 41e... Drain boat, 42... Reducing valve, 43... Gear ratio control valve, 43a... Spool, 43b... Spring, 43c... Line Pressure boat, 43d...Drain boat, 43e...Pilot boat, 43f...Pilot room, 43g.
...Reverse boat, 44...Switching valve, 44a...
Spool, 44b...Spring, 44c...Pilot boat, 44d...First pilot pressure introduction boat, 44e...Second pilot pressure introduction boat, 44f
...Pilot pressure supply boat, 45...Shift valve,
46...Clutch pressure adjustment valve, 47...Lock-up control valve, 48...Relief valve, 51...First electromagnetic solenoid valve, 52...Second electromagnetic solenoid valve, 53...Second electromagnetic solenoid valve 3 electromagnetic solenoid valve, 61...brake chamber, 62...brake chamber, 70...valve housing chamber, 71...flow path 5.72...branch line, 73...
...Reservoir tank, 74...Return line, 75...
・Plunger, 76...Coil spring, 77...
- Electromagnetic coil, 78... Control unit, 82... Shift position sensor, 83... Primary rotation speed sensor,
84... Secondary rotation speed sensor, 85... Throttle opening sensor, 86... Rotation speed sensor, 87...
Turbine speed sensor, 101.102.103104
．． 105, 106, 107, 108° 109... lines.

Claims (1)

[Scope of Claims] A line pressure control device for a belt-type continuously variable transmission in which engine output is transmitted via a torque converter, comprising: a first detection means for detecting turbine torque in the torque converter; and the belt-type continuously variable transmission. A second device that detects the gear ratio in a continuously variable transmission.
A line pressure control device for a belt-type continuously variable transmission, comprising: a detection means; and a control means for controlling line pressure based on the detection results of the first and second detection means.