JPH07122464B2 - Shift control device for continuously variable transmission - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gear shift control device for a belt type continuously variable transmission, and more particularly to a gear shift control device for arbitrarily holding a minimum gear ratio.

[0002]

2. Description of the Related Art A conventional shift control device for a continuously variable transmission of this type is disclosed in, for example, Japanese Patent Laid-Open No. 55-65755. In this prior art, the line pressure is supplied to and drained from the main pulley side by the relationship between the spring force according to the throttle opening and the pitot pressure according to the engine speed in the shift control valve, and the shift control is continuously performed. It is shown.

Therefore, for example, the shift characteristics when a centrifugal clutch and a continuously variable transmission are combined are shown by the solid line in FIG. That is, the clutch is engaged and the vehicle starts to run at rotational speeds N1 and N2 higher than the idle speed Ni of the engine. At this time, since the throttle opening is large, the shift control valve drains the main pulley, so that the vehicle travels at the maximum gear ratio L1. After that, when the engine speed and the pitot pressure increase due to the increase in the vehicle speed, the gear shift is started, and the gear shift is upshifted from P2 to P3 to reach the minimum gear ratio L2.

When the vehicle is decelerated with the throttle fully closed, the Pitot pressure is somewhat high under the condition of a high vehicle speed, so the vehicle is decelerated as P3 → P4 while maintaining the minimum gear ratio L2.
Then, the downshift starts at a time point P4 when the engine speed drops to such a level that the minimum spring force of the shift control valve and the pitot pressure are balanced, and thereafter, as the vehicle speed decreases, the downshift starts.
As in 4 → P5, the engine is downshifted so as to keep the engine speed constant, and the maximum gear ratio L1 is restored.

[0005]

Meanwhile [0007], in the the well of the prior art, the down shift start point P4 is the minimum spring force of the shift control valve, is uniquely set by the Pitot pressure characteristics, this downshift The vehicle speed V2, which is relatively high at the starting point P4, is downshifted, the engine braking is applied, and the deceleration is applied. For this reason, the engine braking may be unnecessarily strongly applied, or the long deceleration may be unfavorable to the driver's experience.

In view of such a problem of the shift control characteristics, the present invention provides a shift control device for a continuously variable transmission, which can arbitrarily maintain a minimum gear ratio to reduce the effect of engine braking. The purpose is to do.

[0007]

SUMMARY OF THE INVENTION To achieve the above object the present invention, in a sub-shaft on the wheel side, which is arranged parallel to the main axis of the engine side of the main shaft Toko, main pulley their respective-pulleys pitch adjusting And a sub-pulley and a drive belt wound between both pulleys
And the effective diameter of the pulley is changed by the hydraulic pressure supplied to each servo device of the main and sub pulleys,
In a continuously variable transmission that continuously controls gear shifting ,
Hydraulic control circuit communicating with each servo device of main and sub pulley
In addition, the spool is controlled by the relationship between the pressure adjustment valve that controls the line pressure supplied to the sub-pulley servo device according to the gear ratio, and the spring force according to the throttle opening and the pitot pressure according to the engine speed. Is at the lubrication or drain position
Provided with a line pressure by operating the main pulley servo device to supply and discharge oil to the gear ratio change control valve which Ru is changed and inspection of the throttle detecting means for detecting a throttle fully closed
Detects that the output signal and vehicle speed are within the specified range on the low speed side
Based on the detection signal of the vehicle speed detection means
When the vehicle speed is within the above specified range when the vehicle is closed,
Characterized in that a minimum speed ratio holding means for holding the spool valve in the oil supply position.

[0008]

[Action] In the present invention having the above structure, the continuously variable transmission is basically the line pressure of the secondary pulley is controlled in accordance with the gear ratio by the pressure regulating valve, the hydraulic pressure supply and discharge to the main pulley at the shift control valve oil
Then, the shift control is performed. And, for example, the throttle is fully closed
When decelerating when the vehicle speed is within the specified range on the low speed side,
The minimum gear ratio holding means forcibly holds the spool of the speed change control valve at the oiling position by the detection signals of the tumble detection means and the vehicle speed detection means, so that the servo device of the main pulley operates. is held in the minimum speed ratio becomes refueling state.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to the drawings. First, referring to FIG. 1, a continuously variable transmission with an electromagnetic powder clutch will be described as an example of the continuously variable transmission to which the present invention is applied. Reference numeral 1 is an electromagnetic powder type clutch, 2
Is a continuously variable transmission. The continuously variable transmission 2 roughly includes a forward / reverse switching unit 3, a pulley ratio conversion unit 4, a final reduction unit 5, and a hydraulic control unit 6.

In the electromagnetic powder clutch 1, a drive member 9 containing a coil 8 is integrally connected to a crankshaft 7 from the engine, while a driven member 11 is integrally splined in a rotational direction to a transmission input shaft 10. These drive and driven members 9 and 11 are coupled to each other to form the gap 12
Electromagnetic powder is accumulated in the gap 12 from the powder chamber 13 by loosely fitting. A slip ring 15 is installed on the drive member 9 via a holder 14, and a brush 16 for supplying a clutch current to the slip ring 15 is slidably contacted with the slip ring 15.

Therefore, for example, when a clutch current is supplied to the coil 8 by operating the lever of the switching unit 3 or by stepping on the accelerator, the magnetic powder generated between the drive and the driven members 9 and 11 causes chain-like electromagnetic powder in the gap 12 between them. Is integrated with the drive member 9 by the coupling force in this case.
On the other hand, the driven member 11 slides and is integrally connected,
Automatically connect the clutch. On the other hand, when the clutch current is cut depending on the running state during deceleration, the coupling force due to the electromagnetic powder disappears, and the clutch is automatically disengaged to prevent engine stall.

Next, in the continuously variable transmission 2, the switching portion 3 is provided between the input shaft 10 from the clutch 1 and the main shaft 17 of the pulley ratio converting portion 4 arranged coaxially with the input shaft 10. . Therefore, a reverse drive gear 18 integrally connected to the input shaft 10 and a reverse driven gear 19 rotatably fitted to the main shaft 17 are meshed with each other via a counter gear 20 and an idler gear 21. A switching clutch 22 is provided between the gear 18 and the gears 18, 19. When the switching clutch 22 is engaged with the gear 18 side from the neutral position of the P or N range, the main shaft 17 is directly connected to the input shaft 10 to move to the forward position of the D or L range, and the switching clutch 22 is engaged with the gear 19 side. When they are matched, the power of the input shaft 10 is reversed by the gears 18 to 21 to the reverse position of the R range.

In the pulley ratio conversion unit 4, a sub shaft 23 is arranged in parallel with the main shaft 17, and a main pulley 24 and a sub pulley 25 are provided on both the shafts 17 and 23, respectively. An endless drive belt 26 is stretched over the. Both of the pulleys 24 and 25 are fixed pulley half bodies 24b and 25b and movable pulley half bodies 24a and 25a.
The movable pulley halves 24a and 25a are provided with hydraulic servo devices 27 and 28, respectively, so that the pulley intervals are variable. Then, the pulleys 24 and 25 are hydraulically operated so that one of the pulleys 24 and 25 has a small gap and the other has a large gap, and the ratio of the winding diameter of the drive belt 26 with respect to the pulleys 24 and 25 is changed to continuously change the speed. It is configured to output the generated power to the counter shaft 23.

The final reduction gear unit 5 includes an intermediate reduction gear 2 on the counter shaft 23.
The output shaft 30 is connected via 9 and the large-diameter final gear 32 meshes with the output gear 31 of the output shaft 30. Then, from the differential mechanism 33 of the final gear 32, the axles 34, 35
It is configured to be transmitted to the left and right driving wheels via.

Further, the hydraulic control section 6 is provided with a hydraulic pump 37 adjacent to the main pulley 24. A pump drive shaft 36 directly connected to the engine crankshaft 7 penetrates the inside of the main shaft 17 and the input shaft 10 and is connected to a hydraulic pump 37,
It is configured to constantly generate hydraulic pressure while the engine is operating. On the other hand, it has a hydraulic control circuit 38 to which the pump hydraulic pressure of the hydraulic pump 37 is supplied, and the hydraulic control circuit 38 and both hydraulic servo devices 27 and 28 are connected by oil passages 39 and 40, respectively.

The hydraulic control circuit 38 will be described with reference to FIG. In the hydraulic servo device 27, the movable half 24a is fitted into the cylinder 27a also as the piston, and the movable half 2a
A servo chamber 27b is provided behind 4a. Also in the hydraulic servo device 28, the movable half 25a is the cylinder 28.
the servo chamber 28b behind the movable half 25a.
Is provided. Here, the pressure receiving area of the movable half of the main pulley 24a is set to be larger than that of the movable half of the auxiliary pulley 25a, so that the hydraulic pressure of the main pulley 24 enables arbitrary shift control.

The suction side of the hydraulic pump 37 has a filter 41.
Through the oil reservoir 42, the discharge side line pressure oil passage 39 of the hydraulic pump 37 communicates with the pressure adjusting valve 43, and the oil passage 40 branched from this oil passage 39 is connected to the sub-pulley servo chamber 28b.
Communicate with. The oil passage 39 further has a shift control valve 44 and communicates with the main pulley servo chamber 27b. Also, the main pulley 2
4 is provided with a rotation sensor 49, which generates pitot pressure according to the main pulley rotation speed when the clutch is disengaged, and generates pitot pressure according to the engine rotation speed when the clutch is connected.

In the shift control valve 44, a spool 46 is movably inserted into a valve body 45, and a throttle cam 51 that lifts in accordance with the throttle opening is provided on one side of the spool 46.
They are connected via an actuating member 48 and a spring 47 that move according to the lift. The Pitot pressure is introduced by the oil passage 50 and acts on the port 45a of the spool 46 on the side opposite to the spring 47. Port 45b of valve body 45
Is selectively communicated with one of the line pressure supply port 45c and the drain port 45d by the lands 46a and 46b of the spool 46, and the port 45b is connected to the oil passage 3
9, the oil passage 39a communicates with the servo chamber 27b, the port 45c communicates with the pressure adjusting valve 43 through the oil passage 39b, and the drain port 45d communicates with the oil sump 42 through the oil passage 52.

In this way, the shift control valve 44 includes the spool 46.
In addition, the Pitot pressure corresponding to the engine speed and the spring force corresponding to the throttle opening act in opposition to each other so that the two always operate in balance. That is, when the spring force is larger, the main pulley servo chamber 27b is drained by the communication between the ports 45b and 45d to reduce the main pulley servo hydraulic pressure, and when the Pitot pressure overcomes the spring force, the port 45b
And 45c communicate with each other to supply the main pulley servo chamber 27b with the line pressure to increase the main pulley servo hydraulic pressure. Then, the shift control is performed so as to upshift or downshift depending on the change in the main pulley servo hydraulic pressure.

Next, the spool 54 of the pressure regulating valve 43 is movably inserted into the valve body 53. A feedback link 56 is attached to the movable half 24a of the main pulley.
It is mounted so as to detect the actual gear ratio according to the movement of a. A feedback link 56 is connected to one side of the spool 54 through a bush 57 and a spring 55, and a pitot pressure is introduced into the port 53a of the spool 54 on the side opposite to the spring 55 by the oil passage 50 to act. A line pressure is introduced to act on the oil passage 39c. The spool 54 communicates with the port 53c and the oil discharge side oil passage 52 by the notch of the land 54a to regulate the pressure.

In this way, the line pressure and the Pitot pressure act on the spool 54 of the pressure regulating valve 43 in the direction of increasing the amount of oil discharged and decreasing the line pressure by the communication of the ports 53c and 53d, and the spring force corresponding to the gear ratio. Acts to increase the line pressure by reducing the amount of oil discharged. As a result, in the case of the maximum gear ratio, the line pressure is controlled to the maximum because the spring force is the largest, and the line pressure is smoothly reduced as the spring force is gradually reduced by shifting from this state to the high speed stage. To control the line pressure. On the other hand, when the pump discharge pressure also increases due to the increase in the engine speed, the drain amount is increased by the Pitot pressure and correction is performed so as to maintain the line pressure control state according to the above gear ratio. Belt slip is prevented by the line pressure, and the pulley pressing force according to the transmitted torque is always applied.

In such a structure, in the present invention, the oil passage 39a, which communicates the shift control valve 44 and the main pulley servo chamber 27b, is divided into oil passages 39a 'and 39a "as the minimum gear ratio maintaining means. A passage switching valve 60 is provided in the bypass oil passage 65 that branches from the oil passages 39a 'and 39a "and the oil passage 39b as the line pressure oil passage.

In the flow path switching valve 60, a spool 62 is inserted into a valve body 61, a return spring 63 is urged to one side of the spool 62, and a solenoid 64 is provided to the other side of the spool 62. The port 61a communicates with the oil passage 39a 'on the main pulley side, the port 61c communicates with the oil passage 39a "on the shift control valve side, the port 61b communicates with the oil passage 65. Depending on whether the solenoid 64 is energized or not, It is configured to switch the port 61a to the port 61b or the port 61c.

Here, the throttle switch has an accelerator switch 66 which is turned on when the throttle is fully closed. Further, as a vehicle speed detecting means, there is provided a vehicle speed switch 67 which is turned on when the vehicle speed is a vehicle speed V2 (for example, V2 = 15 km / h) corresponding to the point P4, and is turned off at a predetermined vehicle speed V1 lower than the vehicle speed V2. 66 and 67 detect the running state after the start of the downshift at the time of deceleration with the throttle fully closed. Both switches 66 and 67 are connected to the solenoid 64 via an AND gate 68.

Next, the operation of this embodiment will be described. First, the vehicle speed switch 67 is turned off when the vehicle is stopped, and the accelerator switch 66 is turned off when the accelerator pedal is running. For this reason, in the flow path switching valve 60, when the solenoid 64 is de-energized, the spool 63 is moved to the right by the spring 63 to connect the ports 61a and 61c. Therefore, the oil passage 65 for bypass is shut off, and the shift control valve 44
Is connected to the main pulley servo chamber 27 by the oil passages 39a 'and 39a ".
It is possible to control the shift by communicating with b and supplying and discharging oil to the main pulley servo chamber 27b by the line pressure by the shift control valve 44.

Therefore, at the start of traveling, the line pressure regulated by the pressure regulating valve 43 is already introduced into the sub-pulley servo chamber 28b and acts. On the other hand, in the shift control valve 44, the force of the spring 47 according to the throttle opening is larger than the pitot pressure according to the engine speed, so that the spool 46 is moved to the right and the port 45b becomes the drain port 4.
The main pulley servo chamber 27b is drained by communicating with 5d. Therefore, the movable half 24a of the main pulley 24 is retracted and the drive belt 26 is wound deeply, and the low speed stage having the maximum gear ratio is achieved.

After the vehicle starts to run at this maximum gear ratio, the pitot pressure increases with the engine speed as the vehicle speed increases, so the spool 46 of the gear shift control valve 44 moves to the left and the port 45b changes to the port 45c. The main pulley servo chamber 27b is communicated with each other by line pressure.
Since the pressure receiving area of the main pulley 24 is larger than that on the sub pulley side, the drive belt 26 is pressed by the hydraulic pressure of the main pulley servo chamber 27b and moves to the main pulley side.
In this way, the winding diameter of the drive belt 26 around the main pulley 24 is gradually increased, and the gear is upshifted to the high speed stage as indicated by P2 → P3 in FIG.

At this time, in the pressure regulating valve 43, the spring 5 is moved by the feedback link 56 in accordance with the upshift.
The force of No. 5 is gradually reduced and changed, and the line pressure is controlled so as to decrease from the state where the maximum gear ratio is the highest.

On the other hand, at the time of deceleration with the throttle fully closed, the spring force in the shift control valve 44 becomes the minimum, but when the vehicle speed is high, the pitot pressure is also somewhat high, so the port 45
The main pulley servo chamber 27b is filled with oil by the communication between b and the port 45c. Therefore, the minimum gear ratio L2 in FIG. 4 is maintained.

When the vehicle speed decreases to the vehicle speed V2 at the downshift starting point P4, the pitot pressure in the shift control valve 44 becomes smaller than the minimum spring force. Therefore, the ports 45b and 45d communicate with each other to operate to drain the main pulley servo chamber 27b.

At this time, in addition to the accelerator switch 66 already being turned on, the vehicle speed switch 67 is also turned on, and the solenoid 64 of the passage switching valve 60 is energized by the output signal from the AND gate 68. Therefore, in the flow path switching valve 60, the ports 61a and 61b are switched so as to communicate with each other, and the oil passage 6
The line pressure of 5 bypasses the speed change control valve 44 and is supplied to the main pulley servo chamber 27b to be maintained in a refueling state. Therefore, regardless of the operation of the shift control valve 44, the minimum speed ratio L2 is maintained as shown by the broken line in FIG. 4, and the vehicle speed is further reduced in the state where the engine braking is ineffective.

When a predetermined vehicle speed V1 is reached, the vehicle speed switch 67 is also turned off, the flow path switching valve 60 returns to its original state, the oil passages 39a 'and 39a "communicate with each other, and the main pulley servo chamber 27b shifts. Oil is drained by the control valve.Therefore, as shown in Fig. 4, a downshift starts at a point P4 'of the vehicle speed V1, and after that, the engine speed is reduced by the downshift and the vehicle speed further decreases to return to the low speed stage. In the above embodiment, the oil passage 65 may of course communicate with any place as long as it is in the oil passage 39b.

Another embodiment of the present invention will be described with reference to FIG. In this embodiment, as the minimum gear ratio maintaining means, the solenoid 64 is provided on the spool 46 of the transmission control valve 44 on the side opposite to the spring 47 , that is, on the oil supply side of the pitot pressure.
Are lined up. The solenoid 64 frees the spool 46 when an electric signal is not input, and enables speed change control according to a running state. Lock it. Further , an accelerator switch 66 as a throttle detecting means and a vehicle speed switch 6 as a vehicle speed detecting means.
7 and 7, when the throttle is fully closed and the vehicle speed is in the range of V2 and V1, the AND gate 68 is connected to output an electric signal to the solenoid 64.

Therefore, in this embodiment, when the vehicle speed is in the range of V2 and V1 during deceleration with the throttle fully closed, the spool 46 of the shift control valve 44 is locked by the solenoid 64 at the refueling position. Therefore, the line pressure of the oil passage 39b is maintained in a state in which the oil is fed to the main pulley servo chamber 27b by the oil passage 39a, and thus is maintained at the minimum speed ratio L2 as shown by the broken line in FIG. 4 regardless of the traveling state.

The region where the minimum gear ratio L2 is held is
Increase the vehicle speed to V1 or less, and engine speed Ni and N1
You can also set up between. Further, it goes without saying that the present invention can be applied to clutches other than the electromagnetic powder type clutch.

[0036]

As described above, according to the present invention, the screen
The deceleration running when the rottle is fully closed and the vehicle speed is within the specified range on the low speed side.
When traveling, check the throttle detection means and vehicle speed detection means.
The minimum speed ratio holding means controls the spool of the speed change control valve by the output signal.
Of the continuously variable transmission by forcibly holding the
Since the minimum gear ratio is maintained , engine braking can be reduced, and discomfort and shock due to great deceleration are eliminated. When the vehicle is stopped, the original maximum speed ratio is restored, so there is no hindrance to running performance, and engine stall during a sudden stop can be prevented.

The minimum speed ratio holding means, using the function of the shift control valve is held in forced lubrication positions its spool
To keep the continuously variable transmission at the minimum speed ratio
, The dedicated valve is unnecessary and the circuit is simplified. Further, after the minimum gear ratio is maintained, it is possible to smoothly shift to normal gear shift control.

[Brief description of drawings]

FIG. 1 is a skeleton diagram showing an example of a continuously variable transmission to which the present invention is applied.

FIG. 2 is a configuration diagram showing an embodiment of an apparatus according to the present invention.

FIG. 3 is a configuration diagram of a main part showing another embodiment.

FIG. 4 is a diagram of shift characteristics.

[Explanation of symbols]

 2 continuously variable transmission 17 main shaft 23 sub shaft 24 main pulley 25 sub pulley 26 drive belt 27 main pulley servo device 28 sub pulley servo device 43 pressure adjusting valve 44 speed change control valve 46 spool 64 solenoid 66 accelerator switch 67 vehicle speed switch

Claims (1)

[Claims] To the auxiliary shaft according to claim 1] wheel side which is arranged parallel to the engine side of the main shaft Toko of the spindle, respectively a main pulley and secondary pulley-pulleys interval variable Re, driving wound around between both pulleys A belt, and the effective diameter of the pulley is changed by the hydraulic pressure supplied to each servo device of the main and sub pulleys, and the pulley between the main and sub shafts is changed.
In a continuously variable transmission that continuously controls the gear ratio , the hydraulic control that communicates from the hydraulic source to each servo device of the main and sub pulleys.
The control circuit controls the line pressure supplied to the sub-pulley servo device according to the gear ratio, the spring force according to the throttle opening, and the pitot pressure according to the engine speed. Depending on the spool position or oil drain
Provided with a main pulley servo device to supply and discharge oil to shift control valve Ru changing the speed ratio line pressure by operating the position detection signal of the throttle detecting means for detecting a throttle fully closed
Detects that the vehicle number and vehicle speed are within the specified range on the low speed side
The throttle is fully closed based on the detection signal from the vehicle speed detection means.
When decelerating when the vehicle speed is within the specified range on the low speed side,
The shift control device for a continuously variable transmission, characterized in that a minimum speed ratio holding means for holding a spool of the control valve to the oil supply position.