KR20040082736A - Pressure control valve for the non-step transmission of pressure control type - Google Patents

Abstract

PURPOSE: A pressure control valve of a pressure control-type continuously variable transmission is provided to prevent belt slip even under a quick shift condition and to linearly control the internal pressure of a driving pulley. CONSTITUTION: In a pressure control valve of a pressure control-type continuously variable transmission, pilot pressure controlled by a solenoid valve acts on one pressure chamber of a three-direction spool valve, driving pulley action pressure supplied to a driving pulley cylinder is fed back in the other pressure chamber, and the axial force of a driving pulley is controlled. The pressure control valve of the pressure control-type continuously variable transmission comprises a solenoid(21); a pilot valve(22) controlling the pilot pressure by a poppet(26) working in proportion to the current by a solenoid plunger(29); and a main valve(23) working by a spool(25) and having a pilot chamber and a feedback chamber, to control the internal pressure of the driving pulley in proportion to the current applied to the solenoid. Oil supplied by a pump(15) flows into the pilot chamber through a supply orifice(24). A flux flows into the feedback chamber through a feedback orifice(31) if the internal pressure of the driving pulley rises by disturbance.

Description

PRESSURE CONTROL VALVE FOR THE NON-STEP TRANSMISSION OF PRESSURE CONTROL TYPE}

The present invention relates to a pressure control valve of a continuously controlled variable pressure control system, and more particularly, to a pressure control valve which is easier to control than a flow control method and can prevent a belt slip even under a sudden shift condition.

The hydraulic control system of the continuously variable transmission has a unique form for each type of transmission according to the configuration of the hydraulic circuit and the type of valve to be applied. In the hydraulic control system, the speed ratio control system is largely divided into two types, a flow control method and a pressure control method, and can be classified in detail according to the type of solenoid valve used and the type of the speed ratio valve.

1 illustrates a flow control method employed in a conventional continuously variable transmission.

As shown, in the flow rate control method, the desired speed ratio is obtained by changing the flow rate toward the drive pulley by the opening degree change control of the speed ratio control valve. The reason why the conventional continuously variable transmission adopts the flow control method is that in the case of the mechanical hydraulic continuously variable transmission, the position control of the spool is relatively easy by the mechanical feedback using the linkage, and it is driven even when the transmission ratio is controlled by the electronic control. It is because the flow rate control method is simple to perform only the speed ratio control without the axial force control on the pulley side.

However, when it is necessary to maintain a constant speed ratio in the continuously variable transmission, the flow rate control method is not easy to control. The reason is that the flow rate control method is difficult to prevent the belt slip even in a sudden shift condition because the axial force on the drive pulley side can not be controlled by controlling the flow rate by controlling the position of the transmission valve spool by external control.

Accordingly, an object of the present invention is to solve such a conventional disadvantage, and an object of the present invention is to provide a continuously variable transmission of a pressure control method capable of preventing belt slip even under a sudden shift condition.

In addition, the present invention is capable of linearly controlling the internal pressure of the drive pulley, good response by mechanical feedback by the feedback orifice, and abnormal sound due to spool vibration at the time of discharge of pressure in the drive pulley due to the opening degree switching and disturbance. It is another object to provide a pressure control valve that can suppress the occurrence.

The present invention is to achieve the above object, in the pressure-controlled continuously variable transmission, a three-way spool valve having three ports, the pilot pressure controlled by the solenoid valve is applied to one pressure chamber of the valve and the other One pressure chamber is provided with a pressure control valve of a pressure-controlled continuously variable transmission characterized in that the driving pulley working pressure supplied to the driving pulley cylinder is fed back to control the axial force of the driving pulley.

According to a preferred embodiment of the invention, the solenoid; A pilot valve controlling the pilot pressure by a poppet operated in proportion to the amount of current by the plunger of the solenoid; The pilot chamber (Vp) operated by the spool, and the oil supplied by the pump flows through the supply orifice, and the feedback chamber (Vf) where the flow rate flows through the feedback orifice when the pressure inside the driving pulley increases due to the disturbance. And a main valve controlling a pressure in the driving pulley in proportion to the current applied to the solenoid.

1 is a principle diagram showing a flow control method adopted in a conventional continuously variable transmission,

2 is a hydraulic circuit diagram of a continuously variable transmission of the pressure control method according to the present invention;

3 is a conceptual diagram for explaining the principle of the pressure control valve according to the present invention;

4 is a cross-sectional view showing an example of a pressure control valve according to the present invention;

5 is a cross-sectional view showing a spool sleeve according to the present invention;

6 is a cross-sectional view showing a spool according to the present invention;

7 is an enlarged cross-sectional view showing part A of FIG. 6 according to the present invention;

8 is an enlarged cross-sectional view showing part B of FIG. 6 according to the present invention;

9 is a graph of the static characteristics test results of the pressure control valve according to the present invention;

10 is a graph of a test result of measuring a control pressure change according to a control flow rate change;

11 is a result graph for the step response characteristic for the pressure control valve.

<Description of the symbols for the main parts of the drawings>

21; Solenoid 22; Pilot valve

23; Main valve 24; Supply orifice

25; Spool 26; Poppet

27; Poppet port 28; Return orifice

29; Plunger 30; Supply port

31; Feedback orifice 32; Return port

40; Housing 41; First recess

42; Second recess 44; Control port

46; Pilot passage 47; Spool sleeve

48; Orifice 49; cap

50; Spring 51; Poppet feet

52; Poppet sleeve 53; Euro

54; First inner diameter extension 55; 2nd inner diameter extension

56; Middle part 57; Through hole

58; Outer diameter narrow 59; Circular groove

60; Feedback orifice 61; incline

62; Oil groove

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

2 is a hydraulic circuit diagram of a continuously variable transmission of a pressure control method according to the present invention, by feeding back the hydraulic pressure on the driving pulley 11 to the pressure control valve 12 to control the pressure acting on the driving pulley 11. Causes a change. To this end, a pressure control valve 12 for controlling the speed ratio of the drive pulley 11, a driven pulley 13, and a pressure reducing valve 14 for controlling the system pressure are provided. The pressure control valve 12 for controlling the speed ratio of the driving pulley 11 is a three-way spool valve having three ports. The pilot pressure controlled by the solenoid valve is applied to one pressure chamber of the valve and the pressure chamber of the other. Has a structure in which the driving pulley working pressure supplied to the driving pulley cylinder is fed back. Reference numeral 15 denotes a pump which is a hydraulic source, and 16 denotes an oil tank for storing oil.

On the other hand, the pressure control method requires a pressure control valve for controlling the axial force of the drive pulley.

3 is a conceptual diagram for explaining the principle of the pressure control valve according to the present invention.

As shown, the pressure control valve controls the hydraulic pressure proportional to the amount of current applied to the solenoid to generate the hydraulic force in accordance with the pressure change in the hydraulic actuator (not shown) which is the final driving pulley. The pressure control valve 12 is largely comprised of a solenoid 21, a pilot valve 22, and a main valve 23.

The operating principle is that the oil supplied by the pump 15, which is the hydraulic source in the steady state, flows into the pilot chamber Vp through the supply orifice 24 and is also formed by the poppet 26; And return to oil tank 16 via return orifice 28. At this time, when the pressures of both chambers of the spool 25 are equal, the spool 25 maintains a neutral position. If the current is increased in the solenoid 21, the plunger 29 generates a force proportional to the amount of current, and the poppet 26 is pushed downward to increase the pressure of the pilot seal Vp, and the poppet 29 is the solenoid 21. And the force acting on the pilot seal (Vp) stops at the equilibrium. Therefore, the pressure of the pilot chamber Vp changes in proportion to the amount of current, and when this pressure rises, the spool 25 moves to the left, and the flow rate flows into the driving pulley through the supply port 30, and thus the pressure (control pressure; Pc). ) Will rise. On the other hand, when the pressure inside the driving pulley increases due to disturbance, the flow rate flows into the feedback chamber Vf through the feedback orifice 31 to increase the pressure in the room, and this pressure is higher than the pressure of the pilot chamber Vp. When the spool 25 is pushed to the right, the flow rate is discharged to the tank 16 through the return port 32 to reduce the pressure inside the driving pulley. This process adjusts the pressure in the drive pulley equal to the pilot seal (Vp) pressure. Therefore, the pressure in the driving pulley, that is, the control pressure Pc is controlled in proportion to the current applied to the solenoid 21.

The feedback function of the pressure control valve 12 which senses the pressure in the driving pulley and keeps it constant works even when the current applied to the solenoid 21 is fixed to a certain value.

4 is a cross-sectional view showing an example of a pressure control valve according to the present invention.

As shown, the pressure control valve according to an embodiment of the present invention has a first recessed portion 41 and a second recessed portion 42 which are machined inside the housing 40, the supply port 30 And control port 44 and return port 32 are formed. The supply port 30 branches inside the housing and communicates with the first recess 41 and the second recess 42, respectively, and the control port 44 is connected to the first recess 41 with the return port 32. Communicates with the second recess 42. On the other hand, the first concave portion 41 and the second concave portion 42 are communicated by the pilot passage 46.

The spool sleeve 47 is inserted into the first recess 41, and the spool 25 is slidably coupled in the longitudinal direction inside the spool sleeve 47, and the first recess 41 is formed by the cap 49. ) Is sealed. The right side of the spool 25 forms a pilot seal Vp and the left side forms a feedback seal Vf. The spring 50 is installed in the feedback chamber Vf to press the spool 25 to the pilot chamber Vp side.

The poppet fit 51, the poppet sleeve 52, and the poppet 26 are inserted into the second recess 42, and the solenoid 21 is coupled to the upper portion thereof. The plunger 29 of the solenoid 21 controls the opening and closing of the flow path 53 formed in the poppet pit 51 by moving the poppet 26 in the vertical direction.

The orifice 48 is detachably installed in the control port 44 and the return port 32 so that replacement is easy if necessary.

5 is a cross-sectional view showing a spool sleeve according to the present invention, Figure 6 is a cross-sectional view showing a spool according to the present invention.

As shown, the spool sleeve 47 has a first inner diameter expansion portion 54 and the second inner diameter expansion portion 55, the inner diameter of which extends in the circumferential direction along the inner circumferential surface are formed at regular intervals, the first and second inner diameters A plurality of through-holes 57 are formed along the circumferential surface of the extensions 54, 55 and the intermediate portion 56 thereof. On the other hand, the spool 26 has a small outer diameter narrow portion 58 is formed in the middle of the cylindrical shape, the circular groove 59 is formed in the longitudinal direction from both ends. Each of the circular grooves 59 forms a pilot seal Vp and a feedback seal Vf together with the spool sleeve 47. In particular, a narrow passage is formed at the center of the feedback seal Vf side circular groove 59 to the outer diameter narrow portion 58 so as to communicate with the outer peripheral surface of the outer diameter narrow portion 58. This narrow passageway forms a feedback orifice 60.

According to the present invention, it is preferable that the first and second inner diameter extensions 54 and 55 of the spool sleeve 47 are not rounded or chamfered at the stepped portion during machining. On the other hand, the outer diameter narrow portion 58 of the spool 25 is preferably rounded and chamfered in the stepped portion, as shown in FIG. 7, but in particular of the inclined surface 61 in contact with the inner circumferential surface of the spool sleeve 47. The outer edge is preferably such that it is not rounded or chamfered. In addition, it is preferable to form an oil groove 62 along the circumferential surface at one end of the outer circumference of the spool 25 (see FIG. 8).

The pressure control valve according to the present invention configured as described above is the most important component in the continuously variable transmission system, and it is possible to linearly control the internal pressure of the driving pulley and be responsive by mechanical feedback by the return orifice. In addition, the following test results showed that the occurrence of abnormal sound due to spool vibration at the time of discharge of pressure in the driving pulley due to the opening degree switching and the disturbance appeared less.

9 is a static characteristic test result of the pressure control valve according to the present invention. As a result of the test, the dead band is less than 0.05 A, which is due to the frictional force and solenoid characteristics generated between the inner spring and each component. When the current is applied from 0 to 1.0 A, the pressure control range is almost linear to 5 to 100 Bar, which not only satisfies the basic performance required in the continuously variable transmission system, but also has excellent linearity with a maximum hysteresis of 4.0% or less.

10 is a test result of measuring the control pressure change according to the control flow rate change. When the amount of current applied to the solenoid was controlled to 100% and 50%, the controlled pressure was 9.6 MPa and 4.8 MPa, and the pressure change controlled when the flow rate in the control pipe was changed was measured. Experimental results show that the higher the pressure, the greater the pressure drop. It is possible to check the degree of compensation of the spool by the feedback spring and feedback orifice inside the pressure control valve.When the input signal is applied to the solenoid at 100%, the pressure drop occurs at 1.6 MPa or less at a flow rate of 10 L / min. When applied at 50%, excellent performance was obtained which is almost proportional to the input signal at 0.8 MPa or less.

FIG. 11 shows that the response time of the valve is 325 msec as the result of the step response characteristic of the pressure control valve based on 2% of the valve settling time.

As described above, according to the present invention, in the case where it is necessary to maintain a constant speed ratio in the continuously variable transmission, the pressure control method has an advantage of easier control than the flow rate control method.

In addition, since the pressure control method according to the present invention can control the axial force on the driving pulley side, it is easy to prevent the belt slip even in a sudden shift condition.

In particular, the pressure control valve according to the present invention can linearly control the internal pressure of the drive pulley, has good response by mechanical feedback by the return orifice, and the spool when the pressure is released in the drive pulley due to the opening degree switching and disturbance. The occurrence of abnormal sounds due to vibration can be suppressed.

What has been described above is only an embodiment of the pressure control valve of the continuously variable transmission according to the present invention, and the present invention is not limited to the above-described embodiment, and is not limited to the scope of the present invention as claimed in the following claims. Without departing from the scope of the present invention, those skilled in the art will have the technical spirit of the present invention to the extent that various modifications can be made.

Claims (7)

In the continuously variable transmission of the pressure control system, It is a three-way spool valve with three ports. The pilot pressure controlled by the solenoid valve is applied to one pressure chamber of the valve and the driving pulley working pressure supplied to the driving pulley cylinder is fed back to the other pressure chamber. Pressure control valve of a pressure control type continuously variable transmission, characterized in that for controlling the axial force. Solenoids; A pilot valve controlling the pilot pressure by a poppet operated in proportion to the amount of current by the plunger of the solenoid; Operated by the spool, the pilot seal (Vp) through which the oil supplied by the pump (15) flows through the supply orifice (24), and when the pressure inside the drive pulley increases due to disturbance, the feedback orifice (31) is opened. A main valve having a feedback chamber Vf through which a flow rate flows and controlling a pressure in the driving pulley in proportion to a current applied to the solenoid 21; Pressure control valve of a pressure control type continuously variable transmission comprising a. The pressure control valve includes a housing having a first recessed portion and a second recessed portion therein, the supply port, the control port and the return port formed therein; The first inner diameter expansion portion and the second inner diameter expansion portion which are inserted into the first concave portion and whose inner diameter extends in the circumferential direction along the inner circumference are formed at regular intervals, and along the circumferential surfaces of the first and second expansion portions and the intermediate portion thereof. A spool sleeve in which a plurality of through holes are formed; It is coupled slidably in the longitudinal direction inside the spool sleeve, the outer diameter of the small diameter is formed in the middle of the cylindrical shape, a circular groove is formed in the longitudinal direction from both ends to be combined with the spool sleeve to form a pilot seal and a feedback seal A spool having a narrow passage formed at a center of the feedback measuring circular groove to an outer diameter narrow portion so as to communicate with an outer circumferential surface of the outer diameter narrow portion to form a feedback orifice; A poppet fit, poppet sleeve and poppet inserted into the second recess; A solenoid installed on the poppet; Pressure control valve of a pressure control system continuously variable transmission comprising a. 4. The pressure control valve of claim 3, wherein the first and second inner diameter expansion portions of the spool sleeve are not rounded or chamfered at the stepped portion during machining. The pressure-controlled continuously variable transmission of claim 3, wherein the outer diameter narrow portion of the spool is rounded and chamfered in the stepped portion, and the outer edge of the inclined surface contacting the inner circumferential surface of the spool sleeve is not rounded or chamfered. Pressure control valve. 4. The pressure control valve of claim 3, wherein an oil groove is formed at one end of the outer circumference of the spool along a circumferential surface thereof. 4. The pressure control valve of claim 3, wherein an orifice is detachably installed in the control port and the return port.