JPS6338749A - Speed change controller for continuously variable transmission - Google Patents

Abstract

PURPOSE:To prevent the hunting of a spool by installing a check valve for permitting only the inflow of the Pitot pressurized oil in a Pitot pressure chamber and an orifice formed in parallel to the valve into the Pitot pressurized oil passage of a speed change control valve. CONSTITUTION:An oil passage 75 having a check valve 71 and an orifice 72 formed in parallel to the valve 71 is formed into a Pitot pressurized oil passage 50 communicating to the Pitot pressure chamber 45e of a speed change control valve 44. The check valve 71 permits only the inflow of the pressurized oil into the Pitot pressure chamber 45e. The orifice 72 directly connects the Pitot pressure chamber 45e and the oil passage 50 so as to bypass the check valve 7. When the number of engine revolution reduces, and the Pitot pressure lowers, a spool 46 is shifted by a spring 47, discharging the line pressure on a primary pulley 24 side. Since, in said shift, the pressurized oil in the Pitot pressure chamber 45e is gradually discharged through the orifice 72, the hunting accompanied with the excessive return of the spool 46 is prevented.

Description

[Detailed description of the invention]

rlA Field of Industrial Application The present invention is directed to a speed change control device for a continuously variable transmission mainly used for vehicles.

[Conventional technology]

Regarding the speed change of the continuously variable transmission as mentioned above,
Japanese Patent Application Laid-open No. 60-159' related to the applicant's previous i-regular business
There is a prior art described in the I55 "5 publication. This is
This system is intended for belt-type continuously variable transmissions that use hydraulic pressure to change the boolean ratio steplessly, and is equipped with a variable speed control valve that switches between supplying and discharging hydraulic oil in the hydraulic system. The above-mentioned speed change control valve is formed with a pressure chamber for receiving Vito pressure oil as the transmission 8, and the transmission control valve receives Bi[-pressure oil according to the rotational speed on the transmission side of the transmission. By moving the spool against the spring force as the fluid flows in, the gear ratio is gradually decreased.

[Problems to be Solved by the Invention] However, in this prior art, since the Vito pressure oil directly flows into and out of the Vito pressure chamber of the speed change control valve,
The spring-loaded spool was prone to hang due to minute fluctuations in Vito pressure. Particularly in the high speed region indicated by the symbol @A in the graph of Fig. 3, the Vito pressure itself is relatively low, and the amount of change in Vito pressure with respect to the change in the rotational speed of the primary pulley is also small. The trend was great. As a result, hysteresis occurs in the gear change control, causing the gear ratio to change periodically, causing unpleasant longitudinal vibrations in the vehicle body. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to control the gear ratio in a stable state, thereby preventing unpleasant longitudinal vibrations occurring in the vehicle body and abnormal fluctuations in oil pressure. [Means for Solving the Problems] For this purpose, the present invention includes a Vito pressure chamber in the hydraulic system of a continuously variable transmission that receives Vito pressure oil according to the rotational speed of the input shaft of the transmission as a control signal. Find out the speed change control valve that has
In a speed change control device for a continuously variable transmission that changes the speed of the continuously variable transmission according to the spool operation of the speed change control valve, Vito pressure oil in the Vito pressure chamber flows into the Vito pressure oil path of the speed change control valve. The gist is that a check valve and an orifice installed in parallel with the check valve are installed.

[For production]

With this means, the Vito pressure oil immediately flows into the Vito pressure chamber of the speed change control valve through the check valve, but flows out from there slowly by passing through the orifice. Therefore, a damping effect is applied to the operation of the spool, and hunting of the spool is prevented, thereby eliminating the -steresis phenomenon in speed ratio control and controlling the speed ratio in a stable state.

[Example] Hereinafter, an example of the present invention will be specifically described with reference to the drawings. FIG. 2 shows a transmission system of a vehicle incorporating a continuously variable transmission to which the present invention is applied, in which reference numeral 1 indicates a lightning powder type ludge and 2 indicates a continuously variable transmission. This continuously variable transmission 2 has a forward/reverse switching section 3. Pulley ratio converter 4. Final reduction section 51'
3 and a hydraulic control section 6. In the electromagnetic powder clutch 1, a drive member 9 having a built-in coil 6 is integrally connected to a crankshaft 7 from the engine, and a driven member 11 is integrally connected in the rotation direction by a spline to a transmission input shaft 1o. These drives and driven members 9゜11 are loosely connected through a gap 12, into which electromagnetic material is supplied from the powder chamber 13).
We are starting to accumulate more and more. In addition, drive member 9
A slip ring 15 is installed through the boulder 14, and a brush 16 for power supply is in sliding contact with the slip ring 15 to cause a clutch current to flow through the coil 8. In this way, when a clutch current is applied to the coil 8, electromagnetic particles are bonded and accumulated in the gap 12 between the drive and driven members 9 and 11 due to the lines of magnetic force generated between the drive and driven members 9 and 11, and the resulting bonding force causes the electromagnetic particles to be attracted to the drive member 9. On the other hand, the driven member 11 slides and becomes integrally connected. On the other hand, when the clutch current is cut, the drive due to the electromagnetic powder and the coupling force between the driven members 9 and 11 disappear, resulting in a clutch disengaged state. In this case, the clutch current is supplied and cut by the I/J of the continuously variable transmission 2.
If the switching part 3 is operated in conjunction with the shift lever etc., it can be changed to P (parking) or neutral to N.
Clutch 1 is automatically engaged when switching from range to D (drive), L (low) or R (reverse) range, eliminating the need for clutch pedal operation. Next, in the continuously variable transmission 2, the forward/reverse switching section 3 is provided between the input shaft 10 from the clutch 1 and the main shaft 17 of the continuously variable transmission R2 disposed coaxially therewith.
A reverse drive member 18 that is integrally connected to the input shaft 10 and a reverse driven drive member 18 that is rotatably fitted to the main shaft 11.
9 are meshed with each other through a counter gear 20J3 and an idler gear 21, and furthermore, these main shaft 17 and gear S? 1
A switching clutch 22 is provided between 8.19 and 19. Then, when the switching clutch 22 is engaged from the neutral position of the P or N range to the gear 18 side, the main shaft 17 is directly connected to the input shaft 10, and the switching clutch 22 is in the forward state of the D or L range.
2 is engaged with the gear 19 side, the power of the input shaft 10 is decelerated and reversed by the gears 18 to 21, and is transmitted to the main shaft 17, resulting in a reverse drive state in the R range. In the boolean ratio conversion unit 4, a subshaft 23 is arranged parallel to the main shaft 17, and primary pulleys 24. A secondary pulley 25 is provided, and an endless drive belt 2 is provided between both pulleys 24.25.
G is sea lion passing. Each of the pulleys 24 and 25 is divided into two parts, with a movable side boot 1 and a half-rest 24a,
Hydraulic servo devices 27 and 213 are attached to 25a to make the boob interval variable. In this case, the primary pulley 24 moves the movable pulley half 24a closer to the fixed bobbin half 24b, and the pulley interval is gradually narrowed;
5b, the movable half-boot half 25a is moved away from the pulley half 25a, and the pulley interval is gradually widened.
．． The winding at 25 changes the ratio of diameters so that continuously variable speed power is extracted to the subshaft 23. In the final reduction section 5, a large-diameter final gear 32 meshes with an output gear 31 of an output shaft 30 connected to the subshaft 23 via an intermediate reduction gear A'I 29, and a differential mechanism 33 is connected to the final gear 32 from the final gear 32. Through the left and right drive wheel axles 34°35
Transmission is configured. Further, the hydraulic control unit 6 includes a hydraulic pump 37 on the primary pulley 24 side so as to constantly generate hydraulic pressure during engine operation through a pump drive shaft 36 that passes through the main shaft 17 and the input shaft 10 and is directly connected to the engine crankshaft 7. is provided. The pump oil pressure of the () lever is controlled by the speed change control device 38 according to the throttle opening degree and engine rotation speed according to the depression of the actuator 2, and is transmitted to the briny brake and each hydraulic pressure on the secondary pulley side via the oil passage 39,40. It is supplied to the servo devices 27 and 211 and is configured to perform continuously variable transmission of the boolean ratio converter 4. To explain the shift control device 38 in FIG. 1,
In the hydraulic servo device 27 on the primary pulley 24 side, the movable pulley half-rest 24a is fitted into the cylinder 27a, which also serves as a screw, and is operated by the line pressure of the servo chamber 27b, and the hydraulic servo device on the secondary pulley 25 side Equipment
Also at f12B, the movable bobber half 25a is fitted into the cylinder 28a and is operated by the line pressure of the servo chamber 28b, and in this case, the pulley half 24a has a lower line pressure than the pulley half 25a. The pressure receiving area is large.The oil passage 40 from the servo chamber 28b of the secondary pulley 25 communicates with the oil reservoir 42 via the hydraulic pump 37 and filter 41, and the oil passage 40 is connected to the hydraulic pump discharge side. Branching from the servo chamber 27b of the primary pulley 24
I: A pressure regulating valve 43 and a speed change control valve 44 are provided in the communicating oil passage 39. The speed change control lO valve 44 has a valve body 45. It consists of a spool 4G, a spring 47 biased to one side of the spool 46, and an actuating member 48 that changes the spring force. Vito pressure corresponding to the engine speed from a rotation sensor 49 provided is guided through an oil passage 50, and a throttle cam 51 that rotates in accordance with the throttle opening is in contact with the operating member 48. Further, the boat 45b of the valve body 45 is configured to selectively communicate with either the line pressure supply boat 450 or the drain boat 45d depending on the positions of the lands 46a and 46b of the spool 46, and the boat 45b is connected to the oil passage 39. communicates with the servo chamber 27b through an oil passage 39a,
The boat 45c communicates with the pressure regulating valve 43 side through the oil passage 39b, and the drain boat 45d communicates with the oil sump 42 side through the drain oil passage 52. As a result, in the spool 46 of the speed change control valve 44, the Vito pressure in the Vito pressure chamber 450 is adjusted according to the engine speed, and the spring 47 is applied in accordance with the throttle opening degree caused by the rotation of the throttle cam 51. The forces act in opposition to each other, and the operation is based on the relationship between these two forces. That is, when the Vito pressure increases as the engine speed increases, the spool 4
6 moves to the left in the drawing, the boats 451) and 45c communicate with each other, supplying line pressure to the servo chamber 27b of the primary pulley 24, and starting a shift to the high speed side where the gear ratio becomes smaller. At this time, the spring 4 corresponding to the throttle opening
The larger the force 7 is, the more the shift start point shifts to the higher engine speed. Next, the pressure regulating valve 43 is connected to the valve body 53. Spool 54
, a spring 55 biased on one side of the spool 54, and boats 53a and 53b on the opposite side of the spool 54 from the spring 55 are each supplied with the Vito pressure of the oil passage 50. The line pressure of the oil passage 39c is guided. Also spring 55
, there is a movable bobbin half 24a of the primary pulley 24.
The feedback sensor 5G that engages with the spring force and detects the actual spring ratio increases the springing force by 11 as the spring ratio increases.
9 are connected to each other. Further, the pump side oil passage 39c is in communication with the oil passage 39b of the speed change control valve 44 regardless of the position of the spool 54. The spool 54 is balanced by the Vito pressure applied to the boat 53a and the force of the spring 55, and communication between the line pressure boat 53C and the boat 53d on the drain oil path 52 side is controlled by movement of the land 548 of the spool 54. This allows exhaust pressure to be controlled. Note that a lubricating oil path 61 branches from the upstream side of the ball check valve 60 of the drain oil path 52, and this rn oil path 61 has a
Aperture 62. Pressure SI! via the exhaust pressure duty solenoid valve 63! A boat 64 on the line pressure decreasing side of the J regulating valve 43 is in communication. And the solenoid valve 63 is
By controlling the exhaust pressure to a small extent when the throttle opening is small by means not shown, a larger lubricating oil pressure acts on the boat 64 as the engine torque becomes smaller. According to the present invention, an oil passage 15 having a check valve 71 and an orifice 72 arranged in parallel with the check valve 71 is stepped in the Vito pressure oil passage 50 communicating with the Vito pressure chamber 45e of the speed change control valve 44. This check valve 71 is made up of a ball valve 74 and a spring 73 built into the boat 45a of the valve body 45 that communicates with the pressure chamber 45e.
Only the inflow of pressure oil into the Vito pressure chamber 45e is allowed, and the outflow is prevented. And this check valve 7
An oil passage 75 with an orifice 72 that directly communicates the Vito pressure chamber 45e and the oil passage 50 is formed in the valve body 45 so as to bypass the oil passage 1. Next, the operation of the shift control device for a continuously variable transmission having such a configuration will be explained. Now, when the forward/reverse switching section 3 of the continuously variable transmission 2 is in the parking range or the neutral range, the engine rotation is not transmitted to the primary pulley 24, so no Vito pressure is generated. Therefore, the speed change control valve 44 operates so that the spool 46 receives only the spring force of the spring 47 so that the boat 4
5b and the boat 45d, and drain the servo chamber 27b of the primary pulley 24. At this time, since the hydraulic pump 37 is operating in two directions as the engine rotates, line pressure is supplied to the servo chamber 28b of the secondary pulley 25, and the boost ratio converter 4
The belt winding has the maximum radius, t, that is, the low gear ratio has the maximum gear ratio. Next, when the forward/reverse switching unit 3 is operated as a drive range and the accelerator is operated, Vito pressure is generated in accordance with the rotation of the primary pulley 24, and this pressure oil passes through the oil passage 50° check valve 71 and the transmission control valve 44. It flows into the Vito pressure chamber 45c. Therefore, when the Vito pressure increases with the upper limit of the engine speed, the spool 46 starts to move against the spring pressure of the spring 47, and eventually the boat 45b and the boat 4
5c to communicate with the servo chamber 27 of the primary pulley 24.
Line pressure is supplied to b. This line pressure is pressure regulated!
! ! ! The spring 55 at 1 ft-43 is subjected to the action of applying spring force by the feedback hinger 56, and the spool 54 is held at a high pressure because υ[pressure is not applied. Then, such line pressure is supplied to the servos 'ff27b and 28b of the primary pulley 24 and the secondary pulley 25, respectively.
Therefore, each pulley half-rest 24a, 25a moves according to the difference in pressure receiving area, and the drive belt 26 is wound [).
By gradually changing the radius, continuously variable shifting to a high speed gear is started. The starting point of the continuously variable transmission is when the accelerator operation is gentle and the throttle opening is small, whereas in the case of sudden acceleration with a large throttle opening, the throttle cam 51 applies spring force to the spring 47 of the speed change control valve 44. This will result in a corresponding delay. For example, in the case of gentle acceleration, the shift start point is around 1600 rpm, whereas in the case of rapid acceleration, the shift start point is around 4000 rl) Il
The shift start point is near l. Therefore, with gentle acceleration, the continuously variable speed starts relatively quickly after starting, and the engine speed is kept approximately constant during that time, whereas with sudden acceleration, the engine speed is approximately 4000 rpm.
Until pm, the low speed gear with a large gear ratio is low 18.
(See Figure 3). When the accelerator pedal is released, the engine speed decreases and the Vito pressure decreases, so in the speed change control valve 44, the spool 46 is moved by the spring pressure of the spring 47 to drain the line pressure on the primary pulley 24 side. do. This movement of the spool 46 is performed stably with sufficient damping effect as the pressure oil in the Vito pressure V 450 gradually flows out through the orifice 72, and hunting caused by the spool 46 returning too much is prevented. . This anti-hunting effect is particularly noticeable in the large gear ratio region on the low gear side where the Vito pressure itself is relatively low. By moving the spool without hunting in this way, the gear ratio can be controlled stably and smoothly. Effects of the Invention As explained above, according to the present invention, hunting of the spool of the speed change control valve is prevented and the speed ratio of the continuously variable transmission is controlled in a stable state, thereby reducing the speed change ratio as in the conventional case. This prevents unpleasant front and rear shots of the vehicle body due to periodic fluctuations in
Further, abnormal fluctuations in the oil pressure of the hydraulic system are also prevented.

[Brief explanation of drawings]

FIG. 1 is a hydraulic circuit diagram showing a shift control I device for a continuously variable transmission according to an embodiment of the present invention, and FIG. 2 is a skeleton diagram of a vehicle transmission system incorporating a continuously variable transmission to which the present invention is applied. , FIG. 3 is a shift characteristic diagram of the continuously variable transmission. 1... Electromagnetic powder clutch, 2... p ((speed change configuration,
3... Forward/forward switching section, 4... Pulley ratio conversion section, 5.
... Final reduction section, 6... Hydraulic control section, 24... Primary pulley, 25... Secondary pulley, 27.28
...hydraulic servo device, 38...speed change control device, 39
．． 40...Line pressure oil path, 43...Pressure regulating valve, 4
4... Speed change control valve, 45... Valve body, 45e...
Vito pressure chamber, 4G...spool, 50...pi [-
Pressure oil passage, 71... Check valve, 72... Orifice, 73... Biasing spring, 74... Ball valve.

Claims (1)

[Claims] The hydraulic system of the continuously variable transmission is equipped with a speed change control valve having a Vito pressure chamber that receives Vito pressure oil according to the rotational speed of the input shaft of the transmission as a control signal. In a speed change control device for a continuously variable transmission that operates a step change transmission, the speed change control valve has a check valve in the Vito pressure oil path that allows only the inflow of Vito pressure oil in the Vito pressure chamber, and an orifice installed in parallel with the check valve. A speed change control device for a continuously variable transmission, characterized in that it is provided with: