JPH03134209A - Variable cam position adjustment device - Google Patents

Abstract

PURPOSE: To make a variable cam phase adjustor axially compact by seating a plurality of return coil springs in the dent of the an inner piston through an outer piston, the coil springs pushing a piston assembly. CONSTITUTION: In a cam phase adjustor 15, a piston assembly 45 comprises an outer piston 43 and an inner piston 44 which are engaged with the respective splines 27, 40 of a spline shaft 26 and a sleeve 39. The pistons 43, 44 are pushed by a corrugated spring washer 48 in a mutually approaching direction to eliminate a backlash. A plurality of return coil springs 64 pushing the piston assembly 45 in the direction for compressing a chamber 52 are seated in the dent 64 of the inner piston 44 through the outer piston 43. Therefore, the cam phase adjustor 15 becomes compact axially.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a phasing drive system, and more particularly to a camshaft phasing system for changing the timing of valve actuation by an engine drive camshaft.

BACKGROUND OF THE INVENTION It is known in the engine valve gearing art to provide various means for varying the valve timing necessary to control engine operation and efficiency. These various variable valve timing devices that have been used in camshaft phasing devices include a variable valve timing device for changing the phase between a rotary input drive member such as a gear, pulley, or sprocket and a rotary driven output member such as a camshaft. There are drive pulleys that incorporate phase changing means. Related prior art includes mechanisms having splined pistons that are hydraulically actuated against springs to change the phase of externally and internally engaging drive and driven members.

Such a mechanism is described, for example, in U.S. Pat. No. 4,231.3.
No. 30 and No. 4,811,698.

OBJECTS OF THE INVENTION The present invention further develops the concepts of the prior art and aims at providing a particularly compact and effective phasing (hereinafter also referred to as phasing) drive.

[Structure and Effects of the Invention] The phase adjuster according to the present invention comprises coaxial driving and driven members interconnected by an annular piston means having inner and outer splines with varying leads; A variable cam phase adjuster, wherein the piston means is axially movable in one direction by a force means to change the phase relationship between the drive member and the driven member, the force means The invention is essentially characterized by a plurality of springs seated within recesses of the annular piston means for biasing the annular piston means in a direction of return opposite to the direction of actuation by the means.

Specifically, a number of return springs engage one of a pair of axially spaced, toward each other biased annular drive pistons to minimize anti-backlash friction during the return movement of the pistons. do.

More specifically, a spring extends from the front cover through one of the pistons to engage the more distant piston (the other piston). This results in a very compact assembly.

Another feature of the invention is the use of a wave spring spring together with a headed pin to bias annular drive pistons with helical splines toward each other, allowing for limited length assembly. It is to absorb the heat in the body.

A further feature of the invention is that a thin sheet oil seal having teeth shaped to closely fit a corresponding hub and shaft is disposed adjacent the inner piston;
The aim is to minimize leakage of pressure oil through the drive piston. The oil seal may be glued to the pressure side of the inner drive piston.

Additionally or alternatively, the sealing effectiveness may be increased by filling the valleys of the (engaged) splines with a deformable material such as wax, epoxy resin, metallic material, plastic material, etc. Both sealing means are intended to minimize the length of the phasing means in order to provide a compact variable cam phaser.

[Example 1] Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS. Fig. 1 shows an engine of the type having a camshaft 11 driven by a motor. The camshaft carries a plurality of cams or lobes (not shown) and controls the engine's cylinder intake and/or exhaust valves (not shown) in a known manner.
Activate. The camshaft is partially supported by an enlarged forward bearing journal 13 carried in a suitable bearing in the front wall 14 of the engine's cylinder head or camshaft carrier.

At the front end, that is, the driven end of the camshaft, there is a sprocket 1.
A phase adjuster 15 having 6 is provided. This sprocket constitutes a driving member, and has an axis 1 coaxial with the camshaft 11.
It has a peripheral drive part or wheel 18 with teeth that engages the chain 12 so as to be rotationally driven on the chain 9 . Inside the wheel 18 is a large front hub 20 extending forward;
A small rear hub 22 extending rearwardly is located. The rear hub 22 abuts the front end of the front journal 13 of the camshaft, and the variable cam phase adjuster is surrounded by a housing 23 and cover 24 mounted on the front wall 14 of the engine.

The variable cam phaser 15 further includes a stub shaft in the form of a spline shaft 26 having an external helical spline 27 at one end and a journal 28 at the other end.

The end of the journal extends through the central opening 29 and is threaded through the screw 3.
0 is fixed to the front end of the camshaft, and the dowel pin 3
1 is housed within the splined shaft 26 and the opening 32.34 of the camshaft 11 to maintain a fixed (constant) driving relationship between the two shafts.

A curved retaining ring 35 engaged in a groove 36 between the journal end of the spline shaft 26 and the spline abuts the sprocket wall adjacent the small rear hub 22 and holds the sprocket hub in place against the camshaft. hold. The axial spring force applied by the curved retaining ring 35 prevents displacement of the sprocket as occurs when torque reversals on the camshaft are transmitted through the helical splines.

The journal end of the hub 22 is movable when the journal 2
It is carried by 8. The splined end of the splined shaft 26 extends forwardly within the forward hub 20 concentrically with the inner diameter 38 of the hub.

Sleeve 39 with internal helical splines 40 is attached to hub 2
0 and maintained in a fixed driving relationship by drive pins 42 or other suitable means such as a shrink fit, adhesive, or the like. The use of a splined sleeve 39 simplifies manufacturing and reduces the axial length by eliminating the need to form undercuts at the inner ends of the inner splines. Opposing splines 27.40 have opposite orientations and (preferably) the same lead (i.e. helical angle).
The phase matching function described below can be performed.

two axially spaced drive pistons between and engaged with both splines 27,40;
That is, an outer piston 43 and an inner piston 44 are provided, the inner piston 44 being located closer (than the outer piston) to the inner wall of the sprocket. Both pistons have inner and outer helical splines that engage respective splines 27.40 of the splined shaft 26 and sleeve 39.

The splines are misaligned so that when the pistons are pushed inward toward each other,
Spline 27.40 to which the piston spline corresponds
This eliminates collisions (which tend to occur when transmitting driving torque between the sprocket 16 and the spline shaft 26). Piston 43.44
are pressed or biased toward each other and are driven by circumferentially spaced pins 46 having heads 47 that are pressed into inner piston 44 and compress wave spring washers 48 on the side remote from outer piston 43. Assembly 45
will be maintained as Since the spring washer has a short axial length, the variable cam phase adjuster 15 becomes compact.

An oil seal 51 made of a thin sheet of deformable material such as an elastomer or oil-resistant plastic is mounted against the inner surface of the inner piston 44 of the assembly 45 and is preferably glued or otherwise secured to the inner surface. Ru.

Seal 51 may be formed with teeth that initially engage spline 27.40 with a tight or slight interference fit. These teeth wear or deform during installation into a tight fitting relationship with the corresponding spline. A very effective seal is therefore obtained, preventing oil loss through the splines.

As an additional seal, the outer and inner splines 27. engage the spline troughs of the inner piston 44.
40 may be filled with a deformable or shearable material such as wax, plastic, or soft metal to minimize oil leakage through these engagements. Alternatively, instead of thin seal 51, a deformable material may be provided on the spline. Whichever method is used, it is possible to prevent an increase in the axial dimension of the device for providing the oil seal.

Seal 51 cooperates with spline 27.40 and the adjacent sprocket wall to define an annular chamber 52. Engine oil pressure is supplied to and discharged from the chamber 52 via a connecting oil passage 54 of the splined shaft 26 and a connecting oil passage 55 provided in the journal 13 of the camshaft and communicating with an annular groove 56 . This annular groove is connected to a solenoid valve 59 via a schematically illustrated passage means 58.
is connected to a three-way valve of suitable form, such as a three-way valve, which operates to supply pressure oil from oil conduit 60 or to discharge oil to a discharge line with flow cut off from conduit 60.

Piston assembly 45 is urged in a direction to compress chamber 52 by eight (or any suitable number) return coil springs 63 . The coil spring 63 passes from the end of the recess 64 of the inner piston 44 through the opening of the outer piston 43,
It extends to the inner surface of a cover 66 that is threaded onto or otherwise held in place on the forward hub 20. Such a configuration allows the variable cam phase adjuster to be made more compact in the axial direction.

Next, the operation will be explained.

In operation of the variable cam phasing regulator 15 according to the embodiment described above, when the solenoid or control valve 59 is not energized, it closes the oil conduit 60 and the annular chamber 5
2 to the drain line 62. Thus, spring 63 can maintain drive piston assembly 45 in the innermost position near the sprocket wall, thereby causing annular chamber 5
The volume of 2 is kept at a minimum. In this position, the camshaft is maintained in a retracted phase relationship with the sprocket by the piston assembly 45, operating the engine valves at the desired retracted (reduced) timing condition.

When engine operating conditions call for advanced (increased) valve timing, the solenoid valve is energized to close drain line 62, open oil conduit 60, and variable cam phasing the pressurized twin oil. into the annular chamber 52 of the vessel 15. Oil pressure causes piston assembly 45 to move to an outermost position adjacent cover 66 against the biasing force of spring 63. Since the inner and outer helical splines 27.40 have opposite leads, outward movement of the piston assembly 45 advances (increases) the timing or phase angle of the camshaft with respect to the sprocket, thereby causing the relative The timing of the engine valves that operate the engine are similarly advanced (earlier).

If the timing is desired to be reduced (slowed down) on demand, the solenoid valve 59 is energized to cut off the flow of oil from the oil conduit 60 and connect the annular chamber 52 of the variable cam phase adjuster to the drain line 62. . As a result, spring 63 returns piston assembly 45 to its initial innermost position adjacent the inner wall of the sprocket.

3-way solenoid valve 59 to control oil flow
This has the advantage of using oil flow only to advance camshaft timing, and blocking oil flow otherwise. Therefore, the capacity and power requirements of the engine oil pump can be reduced. However, other suitable types of valves and oil supply structures may be used to control oil flow into and out of the annular chamber 52. Additionally, the valves and oil passages may be arranged in any desired manner and at any suitable location to accomplish the objectives without departing from the spirit of the invention.

In addition to the phasing function, the pistons 43,44 of the piston assembly 45 move from the sprocket 16 to the camshaft 11.
and also form a means for transmitting all torque from the camshaft to the sprocket via the helical spline and corresponding spline. The misalignment of the piston splines and the bias of these splines towards each other due to the pins 46 and wave washers 48 causes the splines 27 to engage the pistons 43, 44 as previously described.
．． By pressing both sides of 40 into engagement, backlash, which is a gap, is absorbed.

For this mode of operation, the return spring 63 extending through an opening (not referenced) in the outer piston 43 between the recess 64 of the inner piston and the inner surface of the cover 66 provides a double advantage. That is, the overall length of the variable cam phaser can be short, while the length of the return spring can be relatively long to provide sufficient axial movement of the piston assembly 45. Furthermore, during the return stroke, the outer piston 43 is pulled behind the inner piston 44 as the inner piston is moved inward by the return spring, thereby slightly increasing the separation of the pistons from each other, thereby reducing the backlash absorption force. This reduces the friction that resists the return movement of the piston assembly. Therefore, the required force of the return spring can be reduced.

Various alternative embodiments are possible without departing from the spirit of the invention. Several other embodiments of the present invention will be described below, but it goes without saying that the present invention is not limited to these embodiments.

FIG. 4 shows another embodiment of the invention for use with a rubber reinforced timing belt driver. Such drive belts are currently in use and require a relatively oil-free environment. Accordingly, the engine 67 of FIG. 4 carries a camshaft 68 with a forward bearing journal 70 and a sealing flange 71 adjacent the outside thereof. Seal 7
2 engages the outer surface of the flange to prevent oil leakage into the adjacent camshaft drive housing 74.

The variable cam phase adjuster 75 is located at the front end of the camshaft 68.
It will be installed. The variable cam phaser includes a pulley 76 having an outer toothed wheel 78 driven by a timing belt 79 and connected to an inner hub 80. The hub is connected to the journal end 8 of the splined shaft 86.
end wall 82 having a seal-bearing central aperture 83 pivotally supporting 4;
Equipped with. Screws 87 secure spline shaft 86 to camshaft 68 in the same manner as shown in FIG.

Also, in the manner of FIG. 1, the hub 80 receives a sleeve 88 having a helical internal spline 90.

These splines concentrically oppose helical outer splines 91 with opposite leads on the protruding outer end of spline shaft 86. These splines are the first
Backlash-free piston assembly 4 with oil seal 51 biased inwardly by return spring 63 as shown.
5.

The return spring 63 is seated within an annular cover 92 that is sealingly secured to the hub 8o and sealingly engages a sealing surface 94 near the end of the splined shaft 86.

Variable cam phaser 75 defines an annular chamber 52 which is connected to a source of pressurized oil via spline shaft 86 and passages 54,55 in camshaft 68 in the same manner as shown in FIG. It communicates with or drains. The operation of these portions of variable cam phaser 75 is the same as previously described for the embodiment shown in FIGS. 1-3.

In FIG. 4, end wall 82 and cover 92 are in sealing contact with splined shaft 86 to prevent oil leakage to the timing belt. Oil leaking through the piston assembly 45 is drained to the space 95 outside the camshaft sealing flange 71 by means of drain passages 96,98 provided in the spline shaft 86 and the camshaft sealing flange 71.

FIG. 5 shows another embodiment of a variable cam phase adjuster 100, which includes a sprocket 101, a spline shaft 102, a retaining ring 104, and a sleeve 10.
5, a drive piston assembly 106, a return spring 108, and a cover 109, which elements have a slightly different shape than the corresponding elements of the embodiment of FIG. 1, but perform the same function. . The one in FIG. 5 is a spline shaft 102.
The screw 110 that fixes the camshaft (not shown) is also 3
It differs from the one shown in FIG. 1 in that it is equipped with a directional oil control valve.

The threaded shank portion of the screw has an axial feed passage 111 for receiving pressurized oil from a central conduit (not shown) of the camshaft. At the base of the head, passage 11
1 is connected to a valve chamber 112 having opposing first and second valve seats 114,115. A cross passage 116 extends transversely from the valve chamber 112 to an annular space 118 which is connected via a duct 119 to an annular chamber 120 of the piston assembly 106 . A pintle 121 positioned within the valve chamber has a head seatable in the valve seat 114, 115 and a stem 122 extending axially into a socket 123 for driving the screw 110. Stem 122 and valve seat 1
The drain groove 124 between the member for 15 and the valve chamber 112
Connect to the drain.

A solenoid actuator (not shown) or other suitable actuation means may be mounted in place on the associated engine to engage the stem 122 of the valve pintle 121 when required. A sealing ring 125 around the head of the screw 110 blocks the leakage path of pressurized oil from the annular space 118.

In operation, the pintle 121 is seated on the first valve seat 114 to block the flow of pressure oil and drain groove 12
Typically, the solenoid actuator is connected to the stem 12 with sufficient force to drain the oil in the annular chamber 120 through the
It is biased so that it touches 2. Right? When the noid actuator is energized, the force on the stem 122 is released, and due to the force of the engine oil pressure in the feed passage 111,
The pintle 121 separates from the first valve seat 114 and moves to the second valve seat 1.
Seated at 15. This closes the drain groove 124,
Pressurized oil flows into the annular chamber 120 and actuates the drive piston assembly 106 in the manner previously described for previous embodiments. Neutralizing the solenoid actuator returns the device to its original state.

This configuration has the advantage of providing a compact internal control valve that allows use of the variable cam phasing device of the present invention in an appropriately shaped engine.

The invention is not limited to the above disclosure, and the elements of all the embodiments described above can be assembled before installation into the engine and then easily attached to the engine using a single screw. (and can be removed), this screw can be left exposed,
May be covered by a removable central plug. This allows, if necessary, all working parts of the variable cam phasing device to be assembled at the factory before being shipped for installation on the engine.
There is no need to assemble the active parts of the phaser during engine assembly.

Although the embodiments described above have shown the use of internal and external helical splines with opposite leads, a combination of linear and helical splines may be used if desired. Also, inner and outer helical splines with different lead angles may be used. Furthermore, other types of cam devices may be substituted for the illustrated splines provided that they have at least some features of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional perspective view of an engine incorporating a variable cam phase adjuster of the present invention used with a chain drive element, FIG. 2 is a cross-sectional view of the variable cam phase adjuster of FIG. 1, and FIG. Figure 2 is an exploded perspective view of the variable cam phase adjuster; Figure 4 is a sectional view of another embodiment of the variable cam phase adjuster applied to a timing belt driver; FIG. 6 is a cross-sectional view of a third embodiment of a combined variable cam phase adjuster. Explanation of symbols 11: Camshaft 15, 75.100: Variable cam phase adjuster 16: Sprocket 22: Hub 26: Spline shaft 35: Retaining ring 43:
Outer piston 44: Inner piston 48: Spring washer 51 Oil seal 52: Annular chamber 59: Solenoid valve 60/Oil conduit 62: Drain line 63: Return spring 64: Recess 66 Cover 79 = Timing belt 82: End wall
92: Cover 95/Space 96.98: Drain passage 102 Varnish spline shaft 110: Screw 111:
Feed passage 112: Valve chamber 114.115: Valve seat 120: Annular chamber 121: Pintle 124: Drain groove 67 FIG, 4

Claims (1)

Claims: 1. Coaxial drive member (16) and driven member (1) interconnected by annular piston means (43, 44) with inner and outer splines with varying leads.
1), said annular piston means (43, 44) being axially moved in one direction by force means to change the phase relationship between said driving member (16) and driven member (11); Variable cam phase adjuster (
15), in order to bias the annular piston means (43, 44) in a return direction opposite to the direction of actuation by the force means, a plurality of recesses (64) seated in the annular piston means (43, 44); A variable cam phase adjuster characterized by comprising a plurality of springs (63). 2. A variable cam phase adjuster (15) according to claim 1, wherein said force means has pressurized oil supplied in a controlled manner into a pressure oil chamber (52) on one side of said piston means. A variable cam phase adjuster featuring: 3. A variable cam phase adjuster (15) according to claim 2, in which the piston means (43, 44) limit leakage of pressurized oil from the pressure oil chamber (52). A variable cam phaser characterized in that it cooperates with sealing means (51) located adjacent to the chamber (52) and extending into the valleys of the engaged splines. 4. The variable cam phase adjuster (15) according to claim 3, wherein the sealing means (51) is connected to the pressure oil chamber (5).
2) A variable cam phase adjuster characterized in that it has a thin deformable member that engages the side of said piston means (43, 44). 5. The variable cam phase adjuster (15) according to claim 2, wherein the spring (63) is removable and located on the outside of the variable cam phase adjuster (15) remote from the source of pressure oil. A variable cam phase adjuster, characterized in that it is seated on the cover (66). 6. The variable cam phase adjuster (15) according to claim 1, wherein the coaxial driving member (16) and the driven member (1
1) are connected by a pair of axially spaced annular pistons (43, 44) with mismatched inner and outer splines with varying leads;
3, 44) are biased toward each other in order to absorb backlash, and these pistons (43
, 44) is axially movable in the one direction by the force means acting on one of the pistons (44); the spring (63) is adapted to control the return stroke of the piston when the force means is released. During the period, the piston (43, 4
4) a variable cam phase extending through the other piston (43) and seated within the recess (64) of said one piston (44) so as to reduce the backlash absorption friction of said one piston (43); regulator. 7. The variable cam phase adjuster (15, 10
0), the force means is configured to engage the one piston (4).
4), characterized in that it has pressurized oil supplied in a controlled manner into the annular chamber (52, 120) on the side opposite said other piston (43). 8. A variable cam phase adjuster (15) according to claim 7, wherein the spring (63) is removable and located on the outside of the variable cam phase adjuster (15) remote from the source of pressure oil. A variable cam phase adjuster, characterized in that it is seated on the cover (66). 9. The variable cam phase adjuster (15) according to claim 6, characterized in that it comprises a biasing means having a wave spring washer (48) biasing the pistons (43, 44) toward each other. Variable cam phase adjuster. 10. The variable cam phase adjuster (15) according to claim 6, wherein the driven member is a driven camshaft (11).
a splined shaft (26) fixed to the splined shaft (26), said drive member having a hub (22) movably carried on said splined shaft (26); (2
2) to prevent the hub (22) from moving in the axial direction, the hub (22) is connected to the camshaft (11)
A variable cam phaser characterized in that it comprises a curved retaining ring (35) resiliently urging the hub into engagement. 11. The variable cam phase adjuster (15) according to claim 7, wherein the one piston (44) is arranged in the annular chamber (
52) characterized in that it cooperates with sealing means (51) located adjacent to said annular chamber (52) and extending into the valleys of the engaged splines in order to limit the leakage of pressurized oil from said annular chamber (52). Cam phase adjuster. 12. Variable cam phase adjuster (15) according to claim 11
, said sealing means (51) sealing said annular chamber (52).
A variable cam phase adjuster characterized in that it has a thin deformable member that engages the side of said one piston (44) on the ) side. 13. A variable cam phase adjuster (75) according to claim 7, comprising accommodation means (82, 92) for accommodating oil leaked through the piston (43, 44) and an associated oil-influenced drive element (79, ) return passage means (95;
96, 98). A variable cam phase adjuster comprising: 14. The variable cam phase adjuster (15) according to claim 2, wherein the chamber (52) is connected to one of a pressurized oil supply source (60) and a drain (62), and the pressurized oil supply source ( 60) and the other of the drains (62). 15. Variable cam phase adjuster (15) according to claim 14
Variable cam phase adjuster according to the invention, characterized in that said valve means (59) comprises a three-way valve. 16. Variable cam phase adjuster (100) according to claim 7
, the annular chamber (120) is connected to a pressurized oil supply source (
111) and a drain (124), and at the same time connect the other pressurized oil supply source (111) to the same drain (124).
), characterized in that it comprises valve means (121) operative to disconnect the cam phasing device. 17. The variable cam phase adjuster according to claim 16 (100
), characterized in that the valve means (121) comprises a three-way valve. 18. The variable cam phase adjuster according to claim 17 (100
), the three-way valve (121) is supported by a screw (110) that is screwed into a camshaft and receives pressurized oil from the camshaft, and the screw (110) connects the driven member (102) with the screw (110). A variable cam phase adjuster that is fixed to the camshaft. 19. The variable cam phase adjuster according to claim 18 (100
), the three-way valve is capable of reciprocating within the valve chamber (112) between two oppositely located valve seats (114, 115), and the three-way valve is selectively movable in one or the other of the valve seats (114, 115). It has a pintle valve (121) that can be engaged with the
Thereby, communication between the pressurized oil supply source (111) or the drain (124) and the annular chamber (120) is cut off, and the communication between the pressurized oil supply source (111) and the drain (124) or the pressurized oil supply source (111) is thereby cut off. A variable cam phase adjuster characterized in that it allows communication with the annular chamber (120).