JP2004301010A - Oil flow control valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oil flow control valve which is capable of preventing oil leakage due to a clearance between a sleeve and a spool over a wide range from low temperature to high temperature, and which has excellent spool response over the wide range from low temperature to high temperature. <P>SOLUTION: In this oil flow control valve, the coefficient of thermal expansion of the sleeve 11 is set so as to be smaller than that of the spool 12. The clearance is decreased by the coefficient of thermal expansion at a high temperature, therefore the amount of oil leakage in the clearance can be reduced. Even if the clearance is reduced, the response of the spool 12 is not degraded because the viscosity of oil is small. On the other hand, at a low temperature, the clearance is increased by a difference in thermal expansion, therefore the response of the spool 12 can be improved even if the viscosity of oil is high. The clearance is increased, but oil leakage in the clearance can be restrained because oil viscosity is high. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an oil flow control valve for switching a flow direction of oil, and is suitable for use in a hydraulic circuit for a vehicle (for example, a variable valve timing device that varies the advance angle of a camshaft by hydraulic pressure). Technology.
[0002]
[Prior art]
A conventional oil flow control valve will be described with reference to FIG. The oil flow control valve shown in FIG. 5 is used for a variable valve timing device.
The oil flow control valve J1 includes a sleeve J6 formed with input / output ports (in this figure, a hydraulic pressure supply port J2, an advance chamber communication port J3, a retard chamber communication port J4, and a drain port J5), and a sleeve J6. The spool J7 is configured to switch between the input / output ports J2 to J5 by being displaced in the axial direction inside the spool, and an electromagnetic actuator J8 for driving the spool J7 in the axial direction.
[0003]
The spool J7 and the moving core J11 are connected, and by adjusting the amount of current (conduction ratio) applied to the coil J12, the amount of displacement of the spool J7 together with the moving core J11 in the axial direction is adjusted. With this operation, the ratio of the hydraulic pressure applied to the advance chamber and the retard chamber is linearly varied, and the advance amount of the camshaft is linearly varied (for example, see Patent Document 1).
[0004]
[Patent Document 1]
JP-A-10-280919
[Problems to be solved by the invention]
Although not disclosed in Patent Document 1, the sleeve J6 is usually made of aluminum die-cast in consideration of ease of manufacture. The spool J7 is made of iron in consideration of abrasion resistance and foreign matter biting ability. That is, the sleeve material constituting the sleeve J6 was aluminum (including an aluminum alloy), and the spool material constituting the spool J7 was iron.
[0006]
Here, comparing the thermal expansion coefficients of aluminum and iron, aluminum has a higher thermal expansion coefficient than iron. For this reason, as shown in FIG. 6A, the clearance between the sleeve J6 and the spool J7 decreases at low temperatures, and increases as the temperature increases. On the other hand, as shown in FIG. 6 (b), the viscosity of the oil is large at a low temperature, and is smaller at a higher temperature.
[0007]
For this reason, at high temperatures, the clearance between the sleeve J6 and the spool J7 is large and the viscosity of the oil is small, so that the amount of oil leaking through the clearance increases as shown by the arrow A 'in FIG. There's a problem.
Conversely, at low temperatures, the clearance between the sleeve J6 and the spool J7 is small and the viscosity of the oil is large, so that the axial movement resistance of the spool J7 is large. There is a problem that the responsiveness of J7 deteriorates.
[0008]
[Object of the invention]
The present invention has been made in view of the above circumstances, and has as its object to prevent oil leakage due to the clearance between the sleeve and the spool over a wide range from a low temperature to a high temperature, and to achieve a wide range from a low temperature to a high temperature. An object of the present invention is to provide an oil flow control valve having excellent spool responsiveness over a range.
[0009]
[Means for Solving the Problems]
[Means of claim 1]
In the oil flow control valve according to the first aspect, the coefficient of thermal expansion of the sleeve material forming the sleeve is provided to be smaller than the coefficient of thermal expansion of the spool material forming the spool.
With this arrangement, the oil viscosity is low at high temperatures and oil is likely to leak from the clearance.However, at high temperatures, the clearance decreases due to the difference in thermal expansion between the sleeve and the spool. Can be reduced. At high temperatures, the clearance is small, but the viscosity of the oil is small, so that the axial movement resistance of the spool is small, and deterioration of the response of the spool at high temperatures is suppressed.
[0010]
Conversely, when the temperature is low, the viscosity of the oil is large, and the spool is difficult to move in the axial direction due to the oil's viscous resistance.However, at low temperatures, the clearance increases due to the difference in thermal expansion between the sleeve and the spool. Is improved. At low temperatures, the clearance increases, but since the viscosity of the oil is large, oil leakage due to the clearance can be suppressed.
As described above, the oil flow control valve according to the first aspect can prevent oil leakage due to the clearance between the sleeve and the spool over a wide range from a low temperature to a high temperature, and can also prevent oil leakage from a low temperature to a high temperature. The response of the spool can be increased over the range.
[0011]
[Means of Claim 2]
The oil flow control valve adopting the means of claim 2 uses an electromagnetic actuator as a drive means of the spool.
[0012]
[Means of Claim 3]
An oil flow control valve adopting the means of claim 3 is combined with a hydraulic actuator of a variable valve timing mechanism, and transmits a hydraulic pressure generated by a hydraulic pressure source during operation of an internal combustion engine to an advance chamber and a retard chamber. Are relatively supplied and discharged.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described using examples and modifications.
〔Example〕
An embodiment will be described with reference to FIGS.
First, the variable valve timing device will be described with reference to FIG.
[0014]
The variable valve timing device shown in this embodiment is attached to a camshaft (any one of an intake valve, an exhaust valve, and an intake / exhaust camshaft) of an internal combustion engine (hereinafter referred to as an engine). Can be continuously varied.
The variable valve timing device (VVT) includes a variable valve timing mechanism 1 (VCT), a hydraulic circuit 3 having an oil flow control valve 2, and an ECU 4 (abbreviation of engine control unit) for controlling the oil flow control valve 2. It is composed of
[0015]
(Explanation of the variable valve timing mechanism 1)
The variable valve timing mechanism 1 is provided so as to be rotatable relative to the shoe housing 5 (corresponding to a rotary driver) that is driven to rotate in synchronization with the crankshaft of the engine, and is integrated with the camshaft. A vane rotor 6 (corresponding to a rotation follower) that rotates relative to the shoe housing 5 by a hydraulic actuator configured in the shoe housing 5 to rotate the vane rotor 6 relative to the shoe housing 5. Is changed to the advance side or the retard side.
[0016]
The shoe housing 5 is coupled to a sprocket that is driven to rotate by a crankshaft of the engine via a timing belt, a timing chain, or the like, by a bolt or the like, and rotates integrally with the sprocket. As shown in FIG. 4, a plurality of (three in this embodiment) substantially fan-shaped recesses 7 are formed inside the shoe housing 5. Note that the shoe housing 5 rotates clockwise in FIG. 4, and this rotation direction is the advance direction.
On the other hand, the vane rotor 6 is positioned at the end of the camshaft by a positioning pin or the like, and is fixed to the end of the camshaft by a bolt or the like, and rotates integrally with the camshaft.
[0017]
The vane rotor 6 includes a vane 6a that partitions the inside of the recess 7 of the shoe housing 5 into an advance chamber 7a and a retard chamber 7b. The vane rotor 6 is provided rotatably within a predetermined angle with respect to the shoe housing 5. Have been.
The advancing chamber 7a is a hydraulic chamber for driving the vane 6a to the advancing side by hydraulic pressure, and is formed in the concave portion 7 on the anti-rotation direction side of the vane 6a. Is a hydraulic chamber for driving the vane 6a to the retard side by hydraulic pressure. The liquid tightness in each of the chambers 7a and 7b is maintained by the seal member 8 and the like.
[0018]
(Description of hydraulic circuit 3)
The hydraulic circuit 3 supplies and discharges oil to the advance chamber 7a and the retard chamber 7b, and generates a hydraulic pressure difference between the advance chamber 7a and the retard chamber 7b to rotate the vane rotor 6 relative to the shoe housing 5. An oil pump 9 driven by a crankshaft or the like, and an oil flow control valve 2 for switchingly supplying oil pumped by the oil pump 9 to the advance chamber 7a or the retard chamber 7b. .
[0019]
The oil flow control valve 2 will be described with reference to FIG.
The oil flow control valve 2 includes a spool valve 10 including a sleeve 11 and a spool 12, and an electromagnetic actuator 13 that drives the spool 12 in the axial direction.
The sleeve 11 has a substantially cylindrical shape, and has a plurality of input / output ports. Specifically, the sleeve 11 of the present embodiment communicates with the insertion hole 11a that supports the spool 12 slidably in the axial direction, the hydraulic supply port 11b that communicates with the oil discharge port of the oil pump 9, and the advance chamber 7a. An advance chamber communication port 11c, a retard chamber communication port 11d communicating with the retard chamber 7b, and a drain port 11e for returning oil into the oil pan 9a are formed.
[0020]
The hydraulic pressure supply port 11b, the advance chamber communication port 11c, and the retard chamber communication port 11d are holes formed on the side surface of the sleeve 11, and extend from the left side (opposite the coil side) to the right side (coil side) in FIG. , A drain port 11e, an advance chamber communication port 11c, a hydraulic pressure supply port 11b, a retard chamber communication port 11d, and a drain port 11e.
[0021]
The spool 12 includes four large-diameter portions 12a (lands) for blocking ports having outer diameters substantially matching the inner diameter of the sleeve 11 (diameter of the insertion hole 11a). The clearance between the sleeve 11 and the spool 12 (hereinafter, the clearance indicates a radial gap between the sleeve 11 and the large-diameter portion 12a of the spool 12) is a state in which the clearance is minimized due to thermal expansion. , A slidable clearance is set between the sleeve 11 and the spool 12. The relationship between the expansion rate and the clearance will be described later.
[0022]
Between the large-diameter portions 12a, a small-diameter portion 12b for advancing chamber drain and a small-diameter portion 12c for hydraulic pressure supply, which change the communication state of a plurality of input / output ports (11b to 11e) according to the axial position of the spool 12. , A small diameter portion 12d for the retard chamber drain is formed.
The advance chamber drain small diameter portion 12b is for draining the hydraulic pressure of the advance chamber 7a when the hydraulic pressure is supplied to the retard chamber 7b, and the hydraulic supply small diameter portion 12c is provided for the advance chamber 7a or the retard chamber. The hydraulic pressure is supplied to one of the angular chambers 7b, and the small diameter portion 12d for draining the retard chamber is for draining the hydraulic pressure of the retard chamber 7b when the hydraulic pressure is supplied to the advance chamber 7a. is there.
[0023]
The spool 12 is integrally provided with a small-diameter shaft 12e that extends inside a coil 17 described below and that is coupled to a moving core 15 described below by press fitting or the like.
On the other hand, a spring 14 (biasing means) for biasing the spool 12 toward the coil (right side in FIG. 1) is disposed on the opposite side of the spool 12 from the coil (left side in FIG. 1).
[0024]
The electromagnetic actuator 13 includes a moving core 15, a stator 16, a coil 17, a yoke 18, and a connector 19.
The moving core 15 is formed of a magnetic metal (for example, iron) that is magnetically attracted to the stator 16 and is press-fitted and fixed to an end of the shaft 12e. Therefore, the moving core 15 moves in the axial direction integrally with the spool 12.
[0025]
The stator 16 is a magnetic metal (for example, a disc-shaped portion 16a sandwiched between the sleeve 11 and the coil 17) and a cylindrical portion 16b that guides the magnetic flux of the disc 16a to the vicinity of the moving core 15. , Iron), and a main gap MG (magnetic attraction gap) is formed between the moving core 15 and the cylindrical portion 16b.
At the end of the cylindrical portion 16b, a concave portion 16c is formed, into which the end of the moving core 15 is inserted without contact, and when the moving core 15 enters into the concave portion 16c, the moving core 15 is fixed to the stator 16b. The moving core 15 and a part of the stator 16 are provided so as to intersect in the axial direction when sucked into the end of the moving core 15. The end of the cylindrical portion 16b is formed with a taper 16d so that the magnetic attraction does not change with respect to the stroke of the moving core 15.
[0026]
The coil 17 is a magnetic force generating means for generating a magnetic force when energized and causing the moving core 15 to be magnetically attracted to the stator 16, and is formed by winding a number of enamel wires around a resin bobbin 17 a.
The yoke 18 is a magnetic metal (for example, iron) having an inner cylindrical portion 18a covering the periphery of the moving core 15 and an outer cylindrical portion 18b covering the periphery of the coil 17, and includes a claw portion 18c formed on the left side of FIG. It is connected to the sleeve 11 by caulking. The inner cylinder portion 18a transfers the magnetic flux to and from the moving core 15, and a side gap SG (magnetic flux transfer gap) is formed between the moving core 15 and the inner cylinder portion 18a.
The connector 19 is a connection means for making an electrical connection to the ECU 4 via a connection line, and has terminals 19 a connected to both ends of the coil 17 therein.
[0027]
When the coil 17 is turned off, the spool 12 and the moving core 15 are displaced toward the coil (the right side in FIG. 1) by the biasing force of the spring 14 and stop when the coil 17 is turned off.
In this stopped state, the maximum gap of the main gap MG is determined, and the positioning of the spool 12 with respect to the sleeve 11 is performed. In the oil flow control valve 2 of the present embodiment, the spool 12 and the moving core 15 are displaced toward the coil side by the contact between the ring-shaped collar 20 mounted inside the stator 16 and the step 12f formed on the spool 12. A stopper is formed when the operation is performed (when the coil 17 is turned off).
Reference numeral 21 shown in FIG. 1 is an O-ring for sealing, and reference numeral 22 is a cup for preventing oil leakage.
[0028]
(Description of ECU 4)
The ECU 4 controls the amount of current (the energization ratio) supplied to the coil 17 of the electromagnetic actuator 13 in accordance with the operating state of the engine such as the crank angle, the engine rotation speed, and the accelerator opening detected by various sensors. The ECU 4 controls the axial position of the spool 12 to generate operating oil pressure in the advance chamber 7a and the retard chamber 7b according to the operating state of the engine. The ECU 4 supplies the hydraulic pressure to the coil 17 by PWM control or the like. The amount of current is controlled continuously.
[0029]
(Explanation of the operation of the variable valve timing device)
When the ECU 4 advances the camshaft according to the driving state of the vehicle, the ECU 4 increases the amount of current supplied to the coil 17. Then, the magnetic force generated by the coil 17 increases, and the moving core 15 and the spool 12 move to the opposite side of the coil (the left side in FIG. 1: the advance side). Then, the communication ratio between the hydraulic pressure supply port 11b and the advance chamber communication port 11c increases, and the communication ratio between the retard chamber communication port 11d and the drain port 11e increases. As a result, the oil pressure in the advance chamber 7a increases, and conversely, the oil pressure in the retard chamber 7b decreases, and the vane rotor 6 is displaced relatively to the shoe housing 5 to advance the camshaft. I do.
[0030]
Conversely, when the ECU 4 retards the camshaft in accordance with the driving state of the vehicle, the ECU 4 reduces the amount of current supplied to the coil 17. Then, the magnetic force generated by the coil 17 decreases, and the moving core 15 and the spool 12 move to the coil side (the right side in FIG. 1: the retard side). Then, the communication ratio between the hydraulic pressure supply port 11b and the retard chamber communication port 11d increases, and the communication ratio between the advance chamber communication port 11c and the drain port 11e increases. As a result, the oil pressure in the retard chamber 7b increases, and conversely, the oil pressure in the advance chamber 7a decreases, the vane rotor 6 is displaced toward the retard side relative to the shoe housing 5, and the camshaft is retarded. I do.
[0031]
[Features of the embodiment according to the present invention]
In the oil flow control valve 2 of the present embodiment, the coefficient of thermal expansion of the sleeve material of the sleeve 11 is smaller than the coefficient of thermal expansion of the spool material of the spool 12. Specifically, the sleeve 11 is made of iron, and the spool 12 is made of stainless steel, aluminum (including an alloy), resin (PPS, PA, etc.) having a higher coefficient of thermal expansion than iron.
[0032]
With this arrangement, as shown in FIG. 2A, the clearance between the sleeve 11 and the spool 12 increases at low temperatures, and decreases as the temperature increases. On the other hand, as shown in FIG. 2 (b), the viscosity of the oil is large at a low temperature, and becomes smaller at a higher temperature.
[0033]
By providing as described above, at high temperature, the viscosity of the oil is small, and the oil is likely to leak from the clearance. However, at high temperature, the clearance becomes small due to the difference in thermal expansion between the sleeve 11 and the spool 12, and FIG. As shown by arrow A in a), the amount of oil leakage due to the clearance can be reduced. At high temperatures, the clearance is small, but since the viscosity of the oil is small, the axial movement resistance of the spool 12 is small, and the response at high temperatures does not deteriorate.
[0034]
Conversely, when the temperature is low, the viscosity of the oil is large, and the spool 12 is difficult to move in the axial direction due to the viscous resistance of the oil. However, when the temperature is low, the clearance becomes large due to the difference in thermal expansion between the sleeve 11 and the spool 12. 3B, the movement of the spool 12 is facilitated, and the responsiveness of the spool 12 is improved as shown by the arrow B in FIG. At low temperatures, the clearance increases, but since the viscosity of the oil is large, oil leakage due to the clearance can be suppressed.
[0035]
As described above, the oil flow control valve 2 to which the present invention is applied can prevent oil leakage due to clearance over a wide range from a low temperature to a high temperature and can also prevent oil from leaking over a wide range from a low temperature to a high temperature. The response of the spool 12 can be increased.
[0036]
When the oil flow control valve 2 to which the present invention is applied is used for the variable valve timing device, the following effects are obtained.
(1) Since oil leakage from the oil flow control valve 2 is suppressed at a high temperature, the oil discharged from the oil pump 9 can be sent to the hydraulic actuator of the variable valve timing mechanism 1 (VCT) with high efficiency. The operating torque can be increased. Therefore, the variable valve timing mechanism 1 can be downsized and the responsiveness of the variable valve timing mechanism 1 can be improved.
[0037]
(2) Since the response of the spool 12 is improved at low temperatures, the variable control of the valve timing at low temperatures can be performed with high accuracy.
(3) By improving the response of the spool 12 at low temperatures, the output of the electromagnetic actuator (the driving force of the spool 12) can be reduced, and the size of the electromagnetic actuator 13 can be reduced.
[0038]
(Modification)
The variable valve timing mechanism 1 shown in the above embodiment is an example for explaining the embodiment, and any other structure may be used as long as the advance angle can be adjusted by a hydraulic actuator inside the variable valve timing mechanism 1. good.
For example, in the above-described embodiment, an example in which three concave portions 7 are formed in the shoe housing 5 and three vanes 6a are provided on the outer peripheral portion of the vane rotor 6 has been described, but the number of concave portions 7 and the number of vanes 6a are The number of the concave portions 7 and the number of the vanes 6a may be other numbers as long as the number is one or more in terms of the configuration.
Also, an example has been shown in which the shoe housing 5 rotates synchronously with the crankshaft and the vane rotor 6 rotates integrally with the camshaft, but the vane rotor 6 is rotated synchronously with the crankshaft so that the shoe housing 5 rotates integrally with the camshaft. You may comprise.
[0039]
In the above-described embodiment, an example in which the spool 12 having the large-diameter portion 12a and the small-diameter portions 12b to 12d is used has been described. However, the structure of the spool 12 is not limited. May be.
In the above embodiment, an example is shown in which a hole is formed in the side surface of the sleeve 11 to provide input / output ports (in the embodiment, a hydraulic supply port 11b, an advance chamber communication port 11c, a retard chamber communication port 11d, and the like). However, the structure of the sleeve 11 is not limited. For example, a plurality of input / output ports may be formed by forming a through hole in the diameter direction of the sleeve 11.
[0040]
The structure of the electromagnetic actuator 13 shown in the above embodiment is an example for describing the embodiment, and another structure may be used. For example, the moving core 15 may be arranged outside the coil 17 in the axial direction.
In the above-described embodiment, the example in which the spool 12 is displaced to the opposite side of the coil when the coil 17 is turned on is described. However, the spool 12 may be displaced to the side of the coil when the coil 17 is turned on.
[0041]
In the above-described embodiment, an example in which the oil flow control valve 2 to which the present invention is applied is combined with the variable valve timing mechanism 1 is shown. The present invention is applicable.
Further, in the above-described embodiment, the electromagnetic actuator 13 using the magnetomotive force of the coil 17 has been described as an example of the driving means of the spool 12, but the spool 12 may be driven in the axial direction by another driving source.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view along an axial direction of an oil flow control valve (embodiment).
FIG. 2 is a graph showing the relationship between temperature and clearance, and the relationship between temperature and oil viscosity (Example).
FIG. 3 is a graph showing the relationship between the clearance at high temperatures and the amount of oil leakage, and the relationship between the clearance at low temperatures and the spool response time.
FIG. 4 is a schematic view of a variable valve timing device (Example).
FIG. 5 is a cross-sectional view along the axial direction of an oil flow control valve (conventional example).
FIG. 6 is a graph showing the relationship between temperature and clearance, and the relationship between temperature and oil viscosity (conventional example).
[Explanation of symbols]
1 variable valve timing mechanism 2 oil flow control valve 5 shoe housing (rotary drive)
6 Vane rotor (rotary follower)
7a advance chamber 7b retard chamber 10 spool valve 11 sleeve 11b hydraulic supply port (input / output port)
11c Leading chamber communication port (input / output port)
11d Delay chamber communication port (input / output port)
11e drain port (input / output port)
12 Spool 13 Electromagnetic actuator (drive means)
14 Spring 15 Moving core 16 Stator 17 Coil 18 Yoke

Claims (3)

A sleeve formed with an oil input / output port,
A spool that switches the input / output port by being displaced in the axial direction inside the sleeve,
Driving means for driving the spool in the sleeve in the axial direction;
An oil flow control valve comprising
An oil flow control valve, wherein a coefficient of thermal expansion of a sleeve material forming the sleeve is set to be smaller than a coefficient of thermal expansion of a spool material forming the spool. The oil flow control valve according to claim 1,
A moving core coupled to the spool and moving in the axial direction together with the spool;
A coil that generates a magnetomotive force when energized;
An oil flow control valve, comprising: a stator for attracting the moving core by a magnetic force generated by the coil. The oil flow control valve according to claim 1 or 2,
This oil flow control valve is
A rotary drive body that is driven to rotate in synchronization with the crankshaft of the internal combustion engine,
A rotation follower that is provided so as to be relatively rotatable with respect to the rotary driving body and rotates integrally with a camshaft of the internal combustion engine;
By supplying hydraulic pressure to an advance chamber formed between the rotary driving body and the rotation driven body, the camshaft is displaced to the advance side together with the rotation driven body with respect to the rotation driving body, Valve timing for displacing the camshaft to the retard side with the rotary driven body with respect to the rotary drive by supplying hydraulic pressure to a retard chamber formed between the rotary driven body and the rotary driven body. It is combined with a variable mechanism hydraulic actuator,
An oil flow control valve, wherein a hydraulic pressure generated by a hydraulic pressure source is supplied to and discharged from the advance chamber and the retard chamber during operation of the internal combustion engine.

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