(19)
(11)EP 3 364 000 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
16.10.2019 Bulletin 2019/42

(21)Application number: 18152212.9

(22)Date of filing:  18.01.2018
(51)International Patent Classification (IPC): 
F01L 13/00(2006.01)
F01L 1/047(2006.01)

(54)

VARIABLE VALVE-OPERATING DEVICE

VARIABLER VENTILSTEUERUNGSEINRICHTUNG

DISPOSITIF D'ACTIONNEMENT DE SOUPAPE VARIABLE


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 17.02.2017 JP 2017028427

(43)Date of publication of application:
22.08.2018 Bulletin 2018/34

(73)Proprietor: Honda Motor Co., Ltd.
Minato-ku Tokyo 107-8556 (JP)

(72)Inventors:
  • Okano, Noriaki
    Saitama, 351-0193 (JP)
  • Takada, Yoshihiro
    Saitama, 351-0193 (JP)

(74)Representative: Beder, Jens 
Mitscherlich PartmbB Patent- und Rechtsanwälte Sonnenstraße 33
80331 München
80331 München (DE)


(56)References cited: : 
DE-A1-102010 052 173
US-A1- 2015 233 271
US-A1- 2015 136 052
US-A1- 2015 330 270
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description


    [0001] The present invention relates to a variable valve-operating device that changes actuation characteristics for an engine valve or valves of an internal combustion engine.

    [0002] A variable valve-operating device for an internal combustion engine is known in which a cam carrier is fitted around a cam shaft of an engine valve train in a manner to be prevented from relative rotation relative to the cam shaft and to be slidable in an axial direction. The cam carrier has a plurality of cam lobes formed on the outer circumferential surface of the cam carrier. The cam lobes have different cam profiles determining valve actuation characteristics. The cam carrier is moved in the axial direction so that the different cam lobes can act on the engine valve to change valve actuation characteristics (see JP 3 980 699 B, for example).

    [0003] In the variable valve-operating device disclosed in JP 3 980 699 B, lead grooves as spiral grooves are formed in the cam carrier slidably fitted on the cam shaft, and switching pins engage with the lead grooves. The cam carrier is thereby guided in the axial direction and moved or shifted in the axial direction while rotated, so that change of the cam acting on the engine valve can be made.

    [0004] Another example of variable valve-operating device comprising a grooved switching sleeve is disclosed in US 2015/233271 A1.

    [0005] One of the two lead grooves of the cam carrier disclosed in JP 3 980 699 B is a lead groove that shifts the cam carrier in one direction, and the other is a lead groove that shifts the cam carrier in the opposite direction.

    [0006] The one lead groove that shifts the cam carrier either to the one direction or to the opposite direction is a speed increasing side lead groove for changing from a low speed side cam lobe having a small amount of valve lift to a high speed side cam lobe having a large amount of valve lift. The other lead groove is a speed decreasing side lead groove for changing from the high speed side cam lobe to the low speed side cam lobe.

    [0007] The speed increasing side lead groove and the speed decreasing side lead groove both have an axial width corresponding to an amount of movement by which the cam carrier is shifted, and are formed in an outer circumferential surface of the cam carrier so as to be separated from each other in the axial direction.

    [0008] Hence, the cam carrier occupies a large axial width because of the lead grooves, and the cam carrier is correspondingly increased in size.

    [0009] The present invention has been made in view of the above. It is an object of the present invention to provide a variable valve-operating device that can be miniaturized by reducing the axial width of the cam carrier to a small amount.

    [0010] In order to achieve the above object, according to the present invention, there is provided a variable valve-operating device comprising a cam carrier in the form of a cylindrical member fitted around a cam shaft of a valve operating mechanism of an internal combustion engine so as to be inhibited from rotation relative to the cam shaft and slidable in an axial direction of the cam shaft, the cam carrier having a low speed side cam lobe and a high speed side cam lobe formed on an outer circumferential surface of the cam carrier to selectively act on an engine valve, the cam carrier also having lead grooves formed in the outer circumferential surface of the cam carrier and including a speed increasing side lead groove and a speed decreasing side lead groove, the cam lobes having different cam profiles and being adjacent to each other in an axial direction of the cam carrier, and switching pins for engagement with the lead grooves, the switching pins including a speed increasing side switching pin and a speed decreasing side switching pin; the speed increasing side switching pin and the speed decreasing side switching pin being adapted to engageably and disengageably advance into and retreat from the speed increasing side lead groove and the speed decreasing side lead groove, respectively, and one of the cam lobes to selectively act on the engine valve being determined by axially shifting the cam carrier with one of the switching pins selectively advanced to engage with one of the lead grooves of the cam carrier being rotated;
    wherein the speed increasing side lead groove with which the speed increasing side switching pin is engageable is operative for change from the low speed side cam lobe to the high speed side cam lobe and the speed decreasing side lead groove with which the speed decreasing side switching pin engages is operative for change from the high speed side cam lobe to the low speed side cam lobe;
    wherein the speed increasing side lead groove includes: a speed increasing side entry lead groove portion for accepting entry of the speed increasing side switching pin; a speed increasing switching lead groove portion extending from the speed increasing side entry lead groove portion to guide the cam carrier in the axial direction so as to move to a high speed side axial position; and a high speed steady position lead groove portion for enabling the cam carrier guided by the speed increasing switching lead groove portion to rotate steadily at the high speed side axial position;
    wherein the speed decreasing side lead groove includes: a speed decreasing side entry lead groove portion for accepting entry of the speed decreasing side switching pin; a speed decreasing switching lead groove portion extending from the speed decreasing side entry lead groove portion to guide the cam carrier in the axial direction so as to move to a low speed side axial position; and a low speed steady position lead groove portion for enabling the cam carrier guided by the speed decreasing switching lead groove portion to rotate steadily at the low speed side axial position; and
    wherein the speed increasing side entry lead groove portion is formed at a position axially overlapping the low speed steady position lead groove portion, and the speed decreasing side entry lead groove portion is formed at a position axially overlapping the high speed steady position lead groove portion.

    [0011] According to the above arrangement, the speed increasing side entry lead groove portion is formed at an axial position overlapping the low speed steady position lead groove portion, and the speed decreasing side entry lead groove portion is formed at an axial position overlapping the high speed steady position lead groove portion. Thus, the speed increasing side lead groove and the speed decreasing side lead groove are formed so as to overlap each other in the axial direction between the high speed steady position lead groove portion and the low speed steady position lead groove portion, with the high speed steady position lead groove portion and the low speed steady position lead groove portion extending around in a circumferential direction of the cam carrier. Therefore, axial width occupied by both the speed increasing side lead groove and the speed decreasing side lead groove in the cam carrier can be reduced to a small amount. It is thus possible to miniaturize the cam carrier, and in turn miniaturize the variable valve-operating device.

    [0012]  In the above-described arrangement, one of the speed increasing side lead groove and the speed decreasing side lead groove may have a smaller groove width and a larger depth to a groove bottom than the other.

    [0013] According to this arrangement, one of the speed increasing side lead groove and the speed decreasing side lead groove has a smaller groove width and a larger depth to the groove bottom than the other. Thus, the switching pin engaging with the speed increasing side lead groove engages only with the speed increasing side lead groove, and the switching pin engaging with the speed decreasing side lead groove engages only with the speed decreasing side lead groove.

    [0014] Therefore, the switching pin engaged with one lead groove of the lead groove having a smaller groove width and a larger depth to the groove bottom and the lead groove having a larger groove width and a smaller depth to the groove bottom can cross the other lead groove without any hindrance, and can smoothly shift the cam carrier while guided by the same one lead groove at all times, even in a portion intersecting the other lead groove.

    [0015]  In the above-described arrangement, the speed decreasing side lead groove may have a smaller groove width and a larger depth to a groove bottom than the speed increasing side lead groove.

    [0016] According to this arrangement, the speed decreasing side lead groove for change from the high speed side cam lobe to the low speed side cam lobe has a smaller groove width and a larger depth to the groove bottom than the speed increasing side lead groove. Thus, the stroke of the speed decreasing side switching pin to be engaged with the speed decreasing side lead groove having the larger depth to the groove bottom is larger than the stroke of the speed increasing side switching pin. However, because of a low engine speed at the time of change from the high speed side cam lobe to the low speed side cam lobe, the speed decreasing side switching pin can timely advance into and engage with the speed decreasing side entry lead groove portion without a delay even though the speed decreasing side switching pin has a large stroke to engage with the speed decreasing side lead groove.

    [0017] In the above-described arrangement, the speed increasing side switching pin and the speed decreasing side switching pin may be arranged at a same position in the axial direction and at positions separated from each other in a circumferential direction of the cam carrier.

    [0018] According to this arrangement, the speed increasing side switching pin and the speed decreasing side switching pin are arranged at the same position in the axial direction and at positions separated from each other in the circumferential direction. Thus, the speed increasing side switching pin and the speed decreasing side switching pin that engage with the speed increasing side lead groove and the speed decreasing side lead groove overlapping and intersecting each other in the axial direction can be arranged without interfering with each other.

    [Effects of the Invention]



    [0019] According to the present invention, the speed increasing engagement lead groove portion is formed at an axial position overlapping the low speed steady position lead groove portion, and the speed decreasing engagement lead groove portion is formed at an axial position overlapping the high speed steady position lead groove portion. Thus, the speed increasing side lead groove and the speed decreasing side lead groove are formed so as to overlap each other between the low speed steady position lead groove portion and the high speed steady position lead groove portion in the axial direction. Therefore, axial width occupied by both the speed increasing side lead groove and the speed decreasing side lead groove in the cam carrier can be reduced to a small amount. It is thus possible to miniaturize the cam carrier, and in turn miniaturize the variable valve-operating device.

    [0020] 

    FIG. 1 is a perspective view of a variable valve-operating device according to an embodiment of the present invention;

    FIG. 2 is a side view of a cam carrier that is spline-fitted to a cam shaft;

    FIG. 3 is a sectional view taken in the direction of arrows III-III in FIG. 2;

    FIG. 4 is a developed view of a speed increasing lead groove and a speed decreasing lead groove in a lead groove cylindrical portion of the cam carrier;

    FIG. 5 is a sectional view of the lead groove cylindrical portion; and

    FIG. 6 is an explanatory view depicting operational processes of principal members of the variable valve-operating device in the order of lapse of time.


    [Mode for Carrying out the Invention]



    [0021] An embodiment of the present invention will hereinafter be described with reference to the drawings.

    [0022] FIG. 1 is a perspective view of principal parts of a variable valve-operating device 1 according to an embodiment to which the present invention is applied.

    [0023] A cam carrier 3 as a cylindrical member is spline-fitted to a cam shaft 2 of a valve train or valve operating mechanism of a four-stroke internal combustion engine.

    [0024] The cam carrier 3 is prevented from relative rotation with respect to the cam shaft 2, and is fitted to the cam shaft 2 slidably in the axial direction of the cam shaft.

    [0025] The cam shaft 2 is oriented in a left-right direction of a vehicle on which the internal combustion engine is mounted.

    [0026] In the drawings, LH denotes a left direction, and RH denotes a right direction.

    [0027] The cam carrier 3 has a pair of a low speed side cam lobe 3L and a high speed side cam lobe 3H formed respectively on left and right sides in the axial direction on the outer circumferential surface of the cam carrier 3. The low speed side cam lobe 3L and the high speed side cam lobe 3H have different cam profiles and are adjacent to each other on the left and right in the axial direction.

    [0028] Outer diameters of base circles of the cam profiles of the low and high speed side cam lobes 3L and 3H adjacent to each other are equal to each other. The low speed side cam lobe 3L and the high speed side cam lobe 3H are located at the same circumferential position.

    [0029] The low speed side cam lobe 3L and the high speed side cam lobe 3H are in sliding contact with rocker arms 11, respectively, which are swingably supported by a rocker arm shaft 10 and operate to swing the rocker arms 11 to actuate intake and exhaust valves 12, respectively.

    [0030] In the state depicted in FIG 1, the high speed side cam lobes 3H are in sliding contact with the rocker arms 11, and the valves 12 are actuated by the high speed side cam lobes 3H, respectively.

    [0031] Here, when the cam carrier 3 are moved in a right direction, the low speed side cam lobes 3L come into sliding contact with the rocker arms 11, and the valves 12 can be actuated by the low speed side cam lobes 3L, respectively.

    [0032] That is, when the cam carrier 3 is shifted to the right, the cams actuating the valve 12 are changed from the high speed side cam lobes 3H to the low speed side cam lobes 3L, while when the cam carrier 3 is conversely shifted to the left, the cam actuating the valves 12 are changed from the low speed side cam lobes 3L to the high speed side cam lobes 3H.

    [0033] Referring to FIGS. 1 and 2, the cam carrier 3 has a lead groove cylindrical portion 3D formed such that lead grooves 4 and 5 extend around the lead groove cylindrical portion 3D on the left side of the left low speed side cam lobe 3L of the pair of the low and high speed side cam lobes 3L and 3H.

    [0034] The outer diameter of the lead groove cylindrical portion 3D is smaller than the outer diameter of the equal-diameter base circles of the low speed side cam lobe 3L and the high speed side cam lobe 3H.

    [0035] There are two kinds of lead grooves, that is, a speed increasing side lead groove 4 for changing from the low speed side cam lobe 3L to the high speed side cam lobe 3H, and a speed decreasing side lead groove 5 for changing from the high speed side cam lobe 3H to the low speed side cam lobe 3L.

    [0036] As will be noted from FIG. 5, the speed decreasing side lead grooves 5 have a smaller groove width and a larger depth to the groove bottom than the speed increasing side lead grooves 4.

    [0037] A speed increasing side switching pin 8p as an advancing and retreating rod of a speed increasing side solenoid 8 can advance into and engage with the speed increasing side lead groove 4, and retreat and disengage from the speed increasing side lead groove 4.

    [0038] Similarly, a speed decreasing side switching pin 9p as an advancing and retreating rod of a speed decreasing side solenoid 9 can advance into and engage with the speed decreasing side lead groove 5, and retreat and disengage from the speed decreasing side lead groove 5.

    [0039] The speed increasing side switching pin 8p of a cylindrical shape has an outer diameter slightly smaller than the large groove width of the speed increasing side lead groove 4, and can therefore engage with and be in sliding contact with the speed increasing side lead groove 4.

    [0040] Similarly, the speed decreasing side switching pin 9p of a cylindrical shape has an outer diameter slightly smaller than the small groove width of the speed decreasing side lead groove 5, and can therefore engage with and be in sliding contact with the speed decreasing side lead groove 5.

    [0041] Hence, the speed increasing side switching pin 8p engages only with the speed increasing side lead groove 4, and the speed decreasing side switching pin 9p engages only with the speed decreasing side lead groove 5.

    [0042] The speed increasing side solenoid 8 and the speed decreasing side solenoid 9 are located around the periphery of the lead groove cylindrical portion 3D of the cam carrier 3 and at the same axial position, and are separated from each other in the circumferential direction of the lead groove cylindrical portion 3D. As depicted in FIG. 3, the speed increasing side switching pin 8p and the speed decreasing side switching pin 9p are directed to the center axis of the lead groove cylindrical portion 3D and project in directions orthogonal to each other. The speed increasing side switching pin 8p is located ahead of the speed decreasing side switching pin 9p by a phase angle of 90 degrees in the rotational direction of the cam carrier 3.

    [0043] FIG. 4 shows a developed view of the speed increasing side lead groove 4 and the speed decreasing side lead groove 5 formed in the lead groove cylindrical portion 3D.

    [0044] In FIG 4, the speed increasing side lead groove 4 and the speed decreasing side lead groove 5 are shown with scattered dot patterns. The speed decreasing side lead groove 5 is shown with highly denser scattered dots to be thus darker than the speed increasing side lead groove 4.

    [0045] The speed increasing side lead groove 4 includes: a speed increasing side entry lead groove portion 4a for accepting the incoming speed increasing side switching pin 8p; a speed increasing switching lead groove portion 4b extending from the speed increasing side entry lead groove portion 4a to shift the cam carrier 3 to the left in the axial direction to move the cam carrier 3 to a high speed side axial position; and a high speed steady position lead groove portion 4c for enabling the cam carrier 3, after guidance by the speed increasing switching lead groove portion 4b, to rotate steadily at the high speed side axial position.

    [0046] The speed decreasing side lead groove 5 includes: a speed decreasing side entry lead groove portion 5a for accepting the incoming speed decreasing side switching pin 9p; a speed decreasing switching lead groove portion 5b extending from the speed decreasing side entry lead groove portion 5a to shift the cam carrier 3 to the right in the axial direction to move the cam carrier 3 to a low speed side axial position; and a low speed steady position lead groove portion 5c for enabling the cam carrier 3, after guidance by the speed decreasing switching lead groove portion 5b, to rotate steadily at the low speed side axial position.

    [0047] The high speed steady position lead groove portion 4c of the speed increasing side lead groove 4 is formed fully around the lead groove cylindrical portion 3D in the circumferential direction and adjacent to the right edge of the lead groove cylindrical portion 3D. The low speed steady position lead groove portion 5c of the speed decreasing side lead groove 5 is formed fully around the lead groove cylindrical portion 3D in the circumferential direction and adjacent to the left edge of the lead groove cylindrical portion 3D.

    [0048] The speed increasing side entry lead groove portion 4a of the speed increasing side lead groove 4 is formed at a left side position where the speed increasing side entry lead groove portion 4a overlaps, in the axial direction, the low speed steady position lead groove portion 5c of the speed decreasing side lead groove 5. The speed increasing switching lead groove portion 4b (lattice-hatched part in FIG. 4) extends from the speed increasing side entry lead groove portion 4a toward the right side. The speed increasing switching lead groove portion 4b merges into the high speed steady position lead groove portion 4c on the right side.

    [0049] In addition, the speed decreasing side entry lead groove portion 5a of the speed decreasing side lead groove 5 is formed at a right side position where the speed decreasing side entry lead groove portion 5a overlaps, in the axial direction, the high speed steady position lead groove portion 4c of the speed increasing side lead groove 4. The speed decreasing switching lead groove portion 5b (lattice-hatched part in FIG. 4) extends from the speed decreasing side entry lead groove portion 5a to the left side. The speed decreasing switching lead groove portion 5b merges into the low speed steady position lead groove portion 5c on the left side.

    [0050] Hence, the speed increasing side lead groove 4 and the speed decreasing side lead groove 5 are formed so as to axially overlap each other between the high speed steady position lead groove portion 4c and the low speed steady position lead groove portion 5c, and the high speed steady position lead groove portion 4c and the low speed steady position lead groove portion 5c extend circumferentially fully around the lead groove cylindrical portion 3D. Therefore, axial width occupied by both the speed increasing side lead groove 4 and the speed decreasing side lead groove 5 in the cam carrier 3 can be reduced to a smaller width than before.

    [0051] Incidentally, the speed increasing switching lead groove portion 4b (lattice-hatched part in FIG 4) of the speed increasing side lead groove 4, which switching lead groove portion guides the cam carrier 3 to the high speed side axial position, is formed ahead of the speed decreasing switching lead groove portion 5b (lattice-hatched part in FIG. 4), for guiding the cam carrier 3 to the low speed side axial position, of the speed decreasing side lead groove 5 by a phase angle of 90 degrees in the rotational direction.

    [0052] This arrangement is based on the arrangement in which the speed increasing side switching pin 8p is located ahead of the speed decreasing side switching pin 9p by a phase angle of 90 degrees in the rotational direction of the cam carrier 3.

    [0053] The cam carrier 3 is shifted when the base circle common to the low and high speed side cam lobes 3L and 3H of the cam carrier 3 acts on the rocker arms 11, whereby switching between the low speed side cam lobe 3L and the high speed side cam lobe 3H can be performed smoothly.

    [0054] The cam carrier 3 can be configured such that the timing at which the speed decreasing side switching pin 9p engages with the speed decreasing switching lead groove portion 5b to shift the cam carrier 3 to the right and the timing at which the speed increasing side switching pin 8p ahead by a phase angle of 90 degrees in the rotational direction engages with the speed increasing switching lead groove portion 4b to shift the cam carrier 3 to the left, coincide with the timing at which the base circle common to the low speed side cam lobe 3L and the high speed side cam lobe 3H acts on the rocker arms 11.

    [0055] Referring to the explanatory view of FIG 6, description will be made of operation made when switching between the low speed side cam lobes 3L and the high speed side cam lobes 3H is performed by moving the cam carrier 3 in the variable valve-operating device 1, and the low speed side cam lobes 3L and the high speed side cam lobes 3H are made to act on the valves 12 via the rocker arms 11, respectively.

    [0056] FIG. 6 depicts operational processes of principal members of the variable valve-operating device 1 in the order of passage of time.

    [0057] In the state depicted in (1) of FIG. 6, the cam carrier 3 is located at a left side position, and the high speed side cam lobes 3H act on the rocker arms 11, so that the valves 12 are operated according to a valve actuation characteristic set in the cam profile of the high speed side cam lobes 3H.

    [0058] At this time, the speed increasing side solenoid 8 is operated to project the speed increasing side switching pin 8p, which engages with the high speed steady position lead groove portion 4c of the speed increasing side lead groove 4, and the high speed steady position lead groove portion 4c extending fully around the circumference on the right side, so that the cam carrier 3 rotates steadily at a high speed steady position as a left-shifted position.

    [0059] After the speed increasing side solenoid 8 is operated to retract the speed increasing side switching pin 8p from the above state to thus disengage the speed increasing side switching pin 8p from the high speed steady position lead groove portion 4c, the speed decreasing side solenoid 9 is operated to project the speed decreasing side switching pin 9p to advance the switching pin 9p into the speed decreasing side entry lead groove portion 5a of the speed decreasing side lead groove 5, to cause the speed decreasing side switching pin 9p to engage with the speed decreasing side lead groove 5.

    [0060] A state immediately after the speed decreasing side switching pin 9p is advanced into the speed decreasing side entry lead groove portion 5a after the disengagement of the speed increasing side switching pin 8p from the high speed steady position lead groove portion 4c is depicted in (2) of FIG 6.

    [0061] When the cam carrier 3 rotates in this state, the speed decreasing side switching pin 9p engaged with the speed decreasing side entry lead groove portion 5a is moved to the speed decreasing switching lead groove portion 5b to engage with the speed decreasing switching lead groove portion 5b. The speed decreasing switching lead groove portion 5b therefore operates to cause the cam carrier 3 to move rightward in the axial direction and shifts the cam carrier 3 to the right while the cam carrier 3 rotates.

    [0062] The speed decreasing switching lead groove portion 5b is formed so as to intersect the speed increasing side lead groove 4. However, the speed decreasing switching lead groove portion 5b has a smaller groove width and a larger depth to the groove bottom than the speed increasing side lead groove 4. Therefore, even in the portion intersecting the speed increasing side lead groove 4, the speed decreasing side switching pin 9p engaged with the speed decreasing switching lead groove portion 5b can cross the speed increasing side lead groove 4 without any hindrance, and can smoothly shift the cam carrier 3 to the right while guided by the same speed decreasing switching lead groove portion 5b at all times.

    [0063] Further rotation of the cam carrier 3 causes the speed decreasing side switching pin 9p engaged with the speed decreasing switching lead groove portion 5b to move into the low speed steady position lead groove portion 5c. As depicted in (3) of FIG 6, the speed decreasing side switching pin 9p engages with the low speed steady position lead groove portion 5c, and therefore the cam carrier 3 rotates steadily at a low speed steady position as a right-shifted position.

    [0064] The cam carrier 3 is shifted to the right, and rotates steadily at the low speed steady position due to the low speed steady position lead groove portion 5c. Thus, as depicted in (3) of FIG. 6, the low speed side cam lobes 3L act on the rocker arms 11 instead of the high speed side cam lobes 3H, and the valves 12 are operated according to a valve actuation characteristic set in the cam profile of the low speed side cam lobes 3L.

    [0065] When the cam carrier 3 is to be shifted to the left to change the cam lobes acting on the valves 12 from the low speed side cam lobes 3L to the high speed side cam lobes 3H, the speed decreasing side switching pin 9p rotating steadily at the low speed steady position as the right-shifted position is disengaged from the low speed steady position lead groove portion 5c, and thereafter the speed increasing side switching pin 8p is projected and advanced into the speed increasing side entry lead groove portion 4a of the speed increasing side lead groove 4 so that, as depicted in (4) of FIG 6, the speed increasing side switching pin 8p is engaged with the speed increasing side entry lead groove portion 4a.

    [0066] When the cam carrier 3 rotates in this state, the speed increasing side switching pin 8p engaged with the speed increasing side entry lead groove portion 4a moves to the speed increasing switching lead groove portion 4b and engages with the speed increasing switching lead groove portion 4b. The speed increasing switching lead groove portion 4b therefore operates to guide the cam carrier 3 leftward in the axial direction and shifts the cam carrier 3 to the left while the cam carrier 3 rotates.

    [0067] Further rotation of the cam carrier 3 causes the speed increasing side switching pin 8p engaged with the speed increasing switching lead groove portion 4b to move to the high speed steady position lead groove portion 4c. As depicted in (1) of FIG 6, the speed increasing side switching pin 8p engages with the high speed steady position lead groove portion 4c, and therefore the cam carrier 3 rotates steadily at the high speed steady position as the left-shifted position. The high speed side cam lobes 3H act on the rocker arms 11 instead of the low speed side cam lobes 3L, and the valves 12 are operated according to the valve actuation characteristic set in the cam profile of the high speed side cam lobes 3H.

    [0068] The speed increasing switching lead groove portion 4b is formed so as to intersect the speed decreasing side lead groove 5. However, the speed increasing switching lead groove portion 4b has a larger groove width and a smaller depth to the groove bottom than the speed decreasing side lead groove 5. Therefore, even in the portion intersecting the speed decreasing side lead groove 5, the speed increasing side switching pin 8p engaged with the speed increasing switching lead groove portion 4b can cross the speed decreasing side lead groove 5 without any hindrance, and can smoothly shift the cam carrier 3 to the left while guided by the same speed increasing switching lead groove portion 4b at all times.

    [0069] An embodiment of the variable valve-operating device according to the present invention described above in detail produces effects described in the following.

    [0070] As depicted in FIGS. 2 and 4, the speed increasing side entry lead groove portion 4a is formed in a position axially overlapping the low speed steady position lead groove portion 5c, and the speed decreasing side entry lead groove portion 5a is formed in a position axially overlapping the high speed steady position lead groove portion 4c. Thus, the speed increasing side lead groove 4 and the speed decreasing side lead groove 5 are formed so as to overlap each other in the axial direction between the high speed steady position lead groove portion 4c and the low speed steady position lead groove portion 5c, with the high speed steady position lead groove portion 4c and the low speed steady position lead groove portion 5c extending around in the circumferential direction. Therefore, total axial direction width occupied by both the speed increasing side lead groove 4 and the speed decreasing side lead groove 5 in the cam carrier 3 is reduced. It is consequently possible to miniaturize the cam carrier 3, and in turn miniaturize the variable valve-operating device 1.

    [0071] Referring to FIGS. 4 and 5, the speed decreasing side lead groove 5 has a smaller groove width and a larger depth to the groove bottom than the speed increasing side lead groove 4. Thus, the speed increasing side switching pin 8p engages only with the speed increasing side lead groove 4, and the speed decreasing side switching pin 9p engages only with the speed decreasing side lead groove 5. Therefore, the switching pin engaged with one lead groove of the speed decreasing side lead groove 5 having a smaller groove width and a larger depth to the groove bottom and the speed increasing side lead groove 4 having a larger groove width and a smaller depth to the groove bottom can cross the other lead groove without any hindrance, and can smoothly shift the cam carrier 3 while guided by the same one lead groove at all times, even in the portion intersecting the other lead groove.

    [0072] Referring to FIG. 3, the speed decreasing side lead groove 5 for change from the high speed side cam lobe 3H to the low speed side cam lobe 3L has a smaller groove width and a larger depth to the groove bottom than the speed increasing side lead groove 4. Thus, the stroke of the speed decreasing side switching pin 9p to be engaged with the speed decreasing side lead groove 5 having the larger depth to the groove bottom is larger than the stroke of the speed increasing side switching pin 8p. However, because of low engine speed at the time of change from the high speed side cam lobe 3H to the low speed side cam lobe 3L, the speed decreasing side switching pin 9p can timely advance into the speed decreasing side entry lead groove portion 5a and engage with the speed decreasing side lead groove 5 without a delay even though the speed decreasing side switching pin 9p has a large stroke to engage with the speed decreasing side lead groove 5.

    [0073] Referring to FIG. 1, the speed increasing side switching pin 8p and the speed decreasing side switching pin 9p are arranged at the same position with respect to the axial direction and at positions separated from each other by an angle of 90 degrees in the circumferential direction of the cam carrier 3. Thus, the speed increasing side switching pin 8p and the speed decreasing side switching pin 9p for engagement, respectively, with the speed increasing side lead groove 4 and the speed decreasing side lead groove 5 overlapping and intersecting each other in the axial direction, can be arranged without interfering with each other.

    [0074] The speed increasing switching lead groove portion 4b is formed ahead of the speed decreasing switching lead groove portion 5b by a phase angle of 90 degrees in the rotational direction. Therefore, the timing at which the speed decreasing side switching pin 9p engages with the speed decreasing switching lead groove portion 5b and shifts the cam carrier 3 to the right and the timing at which the speed increasing side switching pin 8p ahead by a phase angle of 90 degrees in the rotational direction engages with the speed increasing switching lead groove portion 4b and shifts the cam carrier 3 to the left, can be made to coincide with the timing at which the base circle common to the low speed side cam lobe 3L and the high speed side cam lobe 3H acts on the rocker arms 11. The cam carrier 3 can therefore be smoothly shifted without any hindrance.

    [0075] A variable valve-operating device 1 according to an embodiment of the present invention has been described above.

    [0076] 

    1...Variable valve-operating device, 2...Cam shaft, 3...Cam carrier, 3L...Low speed side cam lobe, 3H...High speed side cam lobe, 3D...Lead groove cylindrical portion,

    4...Speed increasing side lead groove, 4a...Speed increasing side entry lead groove portion, 4b...Speed increasing switching lead groove portion, 4c...High speed steady position lead groove portion,

    5...Speed decreasing side lead groove, 5a...Speed decreasing side entry lead groove portion, 5b...Speed decreasing switching lead groove portion, 5c...Low speed steady position lead groove portion,

    8...Speed increasing side solenoid, 8p...Speed increasing side switching pin, 9...Speed decreasing side solenoid, 9p...Speed decreasing side switching pin,

    10...Rocker arm shaft, 11...Rocker arm, 12...Valve




    Claims

    1. A variable valve-operating device comprising a cam carrier (3) in the form of a cylindrical member fitted around a cam shaft (2) of a valve operating mechanism of an internal combustion engine so as to be inhibited from rotation relative to the cam shaft (2) and slidable in an axial direction of the cam shaft (2), the cam carrier (3) having a low speed side cam lobe (3L) and a high speed side cam lobe (3H) formed on an outer circumferential surface of the cam carrier (3) to selectively act on an engine valve (12), the cam carrier (3) also having lead grooves (4 and 5) formed in the outer circumferential surface of the cam carrier (3) and including a speed increasing side lead groove (4) and a speed decreasing side lead groove (5), the cam lobes (3L and 3H) having different cam profiles and being adjacent to each other in an axial direction of the cam carrier (3), and switching pins (8p and 9p) for engagement with the lead grooves (4 and 5), the switching pins (8p and 9p) including a speed increasing side switching pin (8p) and a speed decreasing side switching pin (9p);
    the speed increasing side switching pin (8p) and the speed decreasing side switching pin (9p) being adapted to engageably and disengageably advance into and retreat from the speed increasing side lead groove (4) and the speed decreasing side lead groove (5), respectively, and one of the cam lobes (3L and 3H) to selectively act on the engine valve (12) being determined by axially shifting the cam carrier (3) with one of the switching pins (8p and 9p) selectively advanced to engage with one of the lead grooves (4 and 5) of the cam carrier (3) being rotated;
    wherein the speed increasing side lead groove (4) with which the speed increasing side switching pin (8p) is engageable is operative for change from the low speed side cam lobe (3L) to the high speed side cam lobe (3H) and the speed decreasing side lead groove (5) with which the speed decreasing side switching pin (9p) engages is operative for change from the high speed side cam lobe (3H) to the low speed side cam lobe (3L);
    wherein the speed increasing side lead groove (4) includes:

    a speed increasing side entry lead groove portion (4a) for accepting entry of the speed increasing side switching pin (8p);

    a speed increasing switching lead groove portion (4b) extending from the speed increasing side entry lead groove portion (4a) to guide the cam carrier (3) in the axial direction so as to move to a high speed side axial position; and

    a high speed steady position lead groove portion (4c) for enabling the cam carrier (3) guided by the speed increasing switching lead groove portion (4b) to rotate steadily at the high speed side axial position;

    wherein the speed decreasing side lead groove (5) includes:

    a speed decreasing side entry lead groove portion (5a) for accepting entry of the speed decreasing side switching pin (9p);

    a speed decreasing switching lead groove portion (5b) extending from the speed decreasing side entry lead groove portion (5a) to guide the cam carrier (3) in the axial direction so as to move to a low speed side axial position; and

    a low speed steady position lead groove portion (5c) for enabling the cam carrier (3) guided by the speed decreasing switching lead groove portion (5b) to rotate steadily at the low speed side axial position; and

    wherein the speed increasing side entry lead groove portion (4a) is formed at a position axially overlapping the low speed steady position lead groove portion (5c), and the speed decreasing side entry lead groove portion (5a) is formed at a position axially overlapping the high speed steady position lead groove portion (4c).


     
    2. The variable valve-operating device according to claim 1, wherein:
    one of the speed increasing side lead groove (4) and the speed decreasing side lead groove (5) has a smaller groove width and a larger depth to a groove bottom than the other.
     
    3. The variable valve-operating device according to claim 2, wherein:
    the speed decreasing side lead groove (5) has a smaller groove width and a larger depth to a groove bottom than the speed increasing side lead groove (4).
     
    4. The variable valve-operating device according to any one of claims 1 to 3, wherein:
    the speed increasing side switching pin (8p) and the speed decreasing side switching pin (9p) are arranged at a same axial position and at positions separated from each other in a circumferential direction of the cam carrier (3).
     


    Ansprüche

    1. Variable Ventilbetätigungsvorrichtung, umfassend einen Nockenträger (3) in der Form eines zylindrischen Elements, welches um eine Nockenwelle (2) angeordnet ist, sodass es an einer Drehung relativ zu der Nockenwelle (2) gehindert wird und in Bezug auf eine axiale Richtung der Nockenwelle (2) verschiebbar ist, wobei der Nockenträger (3) eine Nockenform für eine Seite niedriger Geschwindigkeiten (3L) und eine Nockenform für eine Seite hoher Geschwindigkeiten (3H) an einer äußeren Umfangsoberfläche des Nockenträgers (3) hat um wahlweise mit einem Motorventil (12) zu agieren, wobei der Nockenträger (3) weiterhin Führungsnuten (4 und 5) hat, die an einer äußeren Umfangsfläche des Nockenträgers (3) gebildet sind und eine Führungsnut (4) zur Geschwindigkeitserhöhung und eine Führungsnut (5) zur Geschwindigkeitsreduzierung aufweisen, wobei die Nockenformen (3L und 3H) unterschiedliche Nockenprofile haben und benachbart zueinander in einer axialen Richtung des Nockenträgers (3) sind, und Schaltstifte (8p und 9p) zum Eingreifen in die Führungsnuten (4 und 5), wobei die Schaltstifte (8p und 9p) einen Schaltstift (8p) für die geschwindigkeitserhöhende Seite und einen Schaltstift (9p) für die geschwindigkeitsreduzierende Seite aufweisen;

    der Schaltstift (8p) für die geschwindigkeitserhöhende Seite und der Schaltstift (9p) für die geschwindigkeitsreduzierende Seite sind angepasst um sich eingreifend in und lösend von der Führungsnut (4) für die geschwindigkeitserhöhende Seite und der Führungsnut (5) für die geschwindigkeitsreduzierende Seite zu verschieben und eine der Nockenformen (3L und 3H) ist angepasst um wahlweise auf das Ventil (12) zu wirken, welches durch axiales Verschieben des Nockenträgers (3) mit einem der Schaltstifte (8p und 9p), die wahlweise verschoben werden um mit einer der Führungsnuten (4 und 5) des Nockenträgers (3) zusammenzuwirken, der gedreht wird;

    wobei die Führungsnut (4) mit der der Schaltstift für die geschwindigkeitserhöhende Seite (8p) in Eingriff gebracht werden kann zum Wechsel von der Nockenform (3L) für niedrige Geschwindigkeiten zu der Nockenform (3H) für hohe Geschwindigkeiten betätigbar ist und die Führungsnut (5) für die geschwindigkeitserhöhenden Seite, in die der Schaltstift (9p) für die geschwindigkeitsreduzierende Seite eingreift, zum Wechseln von der Nockenform (3H) für die Seite hoher Geschwindigkeiten zu der Nockenform (3L) für die Seite niedriger Geschwindigkeiten betätigbar ist;

    wobei die Führungsnut (4) für die geschwindigkeitserhöhende Seite umfasst: einen Führungsnuteingangsabschnitt (4a) für die geschwindigkeitserhöhende Seite zum Annehmen der Einführung des Schaltstifts (8p) für die geschwindigkeitserhöhende Seite; einen Führungsnutschaltabschnitt (4b) für die Geschwindigkeitserhöhung, der sich von dem Führungsnuteingangsabschnitt (4a) für die geschwindigkeitserhöhende Seite zu einer Führung des Nockenträgers (3) hin in der axialen Richtung erstreckt um sich zu einer axialen Position für die Seite hoher Geschwindigkeiten zu bewegen; und

    einen Führungsnutabschnitt für eine konstante Position für hohe Geschwindigkeit (4c) um dem Nockenträger (3) zu ermöglichen, der durch den Führungsnutschaltabschnitt (4b) zum Erhöhen der Geschwindigkeit geführt wird, sich konstant an der axialen Position der Seite für hohe Geschwindigkeiten zu drehen;

    wobei die Führungsnut (5) für die geschwindigkeitsreduzierende Seite aufweist:

    einen Führungsnuteingangsabschnitt (5a) für die geschwindigkeitsreduzierende Seite zum Annehmen eines Eingangs des Schaltstifts (9p) für die geschwindigkeitsreduzierende Seite;

    einen Führungsnutschaltabschnitt (5b) für die Geschwindigkeitsreduzierung, der sich von dem Führungsnuteingangsabschnitt (5a) für die geschwindigkeitsreduzierende Seite erstreckt um den Nockenträger (3) in der axialen Richtung zu führen um sich zu einer axialen Position für die niedrige Geschwindigkeitsseite zu bewegen; und

    einen Führungsnutabschnitt für eine konstante Position für niedrige Geschwindigkeit (5c) um dem Nockenträger (3) zu ermöglichen, der durch den Führungsschaltabschnitt (5b) für die Geschwindigkeitsreduzierung geführt wird, sich konstant an der axialen Position für die niedrige Geschwindigkeitsseite zu drehen; und

    wobei der Führungsnuteingangsabschnitt (4a) für die geschwindigkeitserhöhende Seite an einer Position gebildet ist, die axial den Führungsnutabschnitt (5c) für eine konstante Position für niedrige Geschwindigkeiten überlappt und der Führungsnuteingangsabschnitt (5a) für die geschwindigkeitsreduzierende Seite an einer Position gebildet ist, die axial mit dem Führungsnutabschnitt (4c) für eine konstante Position hoher Geschwindigkeit überlappt.


     
    2. Variable Ventilbetätigungsvorrichtung gemäß Anspruch 1, wobei:
    entweder die Führungsnut (4) für die geschwindigkeitserhöhende Seite oder die Führungsnut (5) für die geschwindigkeitsreduzierende Seite eine kleinere Nutenbreite und eine größere Tiefe zu einem Nutengrund hat als die andere.
     
    3. Variable Ventilbetätigungsvorrichtung gemäß Anspruch 2, wobei:
    die Führungsnut (5) für die geschwindigkeitsreduzierende Seite eine schmalere Nutenbreite und eine größere Tiefe bis zu einem Nutengrund hat als die Führungsnut (4) für die geschwindigkeitserhöhende Seite.
     
    4. Variable Ventilbetätigungsvorrichtung gemäß einer der Ansprüche 1 bis 3, wobei:
    der Schaltstift (8p) für die geschwindigkeitserhöhende Seite und der Schaltstift (9p) für die geschwindigkeitsreduzierende Seite an derselben axialen Position angeordnet sind und an Positionen, die separat voneinander in einer Umfangsrichtung des Nockenträgers (3) sind.
     


    Revendications

    1. Dispositif de distribution variable comprenant un porte-came (3) sous la forme d'un organe cylindrique ajusté autour d'un arbre à cames (2) d'un mécanisme de distribution d'un moteur à combustion interne de façon à entraver sa rotation par rapport à l'arbre à cames (2) et coulissant dans une direction axiale de l'arbre à cames (2), le porte-came (3) ayant un bossage de came côté petite vitesse (3L) et un bossage de came côté grande vitesse (3H) formés sur une surface circonférentielle externe du porte-came (3) pour agir sélectivement sur une soupape de moteur (12), le porte-came (3) comportant également des sillons de tête (4 et 5) formés dans la surface circonférentielle externe du porte-came (3) et incluant un sillon de tête côté augmentation de vitesse (4) et un sillon de tête côté diminution de vitesse (5), les bossages de came (3L et 3H) ayant des profils de came différents et étant adjacents l'un à l'autre dans une direction axiale du porte-came (3), et des chevilles de commutation (8p et 9p) pour mise en prise avec les sillons de tête (4 et 5), les chevilles de commutation (8p et 9p) comportant une cheville de commutation côté augmentation de vitesse (8p) et une cheville de commutation côté diminution de vitesse (9p) ;
    la cheville de commutation côté augmentation de vitesse (8p) et la cheville de commutation côté diminution de vitesse (9p) étant adaptées pour avancer dans et se retirer avec faculté de mise en prise et hors de prise du sillon de tête côté augmentation de vitesse (4) et du sillon de tête côté diminution de vitesse (5), respectivement, et l'un des bossages de came (3L et 3H) pour agir sélectivement sur la soupape de moteur (12) étant déterminé en décalant axialement le porte-came (3) avec l'une des chevilles de commutation (8p et 9p) sélectivement avancée pour mise en prise avec l'un des sillons de tête (4 et 5) du porte-came (3) en rotation ;
    dans lequel le sillon de tête côté augmentation de vitesse (4) avec lequel la cheville de commutation côté augmentation de vitesse (8p) peut être mise en prise est opérationnel pour un changement du bossage de came côté petite vitesse (3L) au bossage de came côté grande vitesse (3H) et le sillon de tête côté diminution de vitesse (5) avec lequel la cheville de commutation côté diminution de vitesse (9p) se met en prise est opérationnel pour un changement du bossage de came côté grande vitesse (3H) au bossage de came côté petite vitesse (3L) ;
    dans lequel le sillon de tête côté augmentation de vitesse (4) inclut :

    une portion de sillon de tête d'entrée côté augmentation de vitesse (4a) pour accepter une entrée de la cheville de commutation côté augmentation de vitesse (8p) ;

    une portion de sillon de tête de commutation d'augmentation de vitesse (4b) s'étendant depuis la portion de sillon de tête d'entrée côté augmentation de vitesse (4a) pour guider le porte-came (3) dans la direction axiale de manière à se déplacer vers une position axiale côté grande vitesse ; et

    une portion de sillon de tête de position stable de grande vitesse (4c) pour permettre au porte-came (3) guidé par la portion de sillon de tête de commutation d'augmentation de vitesse (4b) de tourner de façon stabilisée à la position axiale côté grande vitesse ;

    dans lequel le sillon de tête côté diminution de vitesse (5) comporte :

    une portion de sillon de tête d'entrée côté diminution de vitesse (5a) pour accepter une entrée de la cheville de commutation côté diminution de vitesse (9p) ;

    une portion de sillon de tête de commutation de diminution de vitesse (5b) s'étendant depuis la portion de sillon de tête d'entrée côté diminution de vitesse (5a) pour guider le porte-came (3) dans la direction axiale de manière à se déplacer vers une position axiale côté petite vitesse ; et

    une portion de sillon de tête de position stable de petite vitesse (5c) pour permettre au porte-came (3) guidé par la portion de sillon de tête de commutation de diminution de vitesse (5b) de tourner de façon stabilisée à la position axiale côté petite vitesse ; et

    dans lequel la portion de sillon de tête d'entrée côté augmentation de vitesse (4a) est formée à une position chevauchant axialement la portion de sillon de tête de position stable de petite vitesse (5c), et la portion de sillon de tête d'entrée côté diminution de vitesse (5a) est formée à une position chevauchant axialement la portion de sillon de tête de position stable de grande vitesse (4c).


     
    2. Dispositif de distribution variable selon la revendication 1, dans lequel :
    l'un du sillon de tête côté augmentation de vitesse (4) et du sillon de tête côté diminution de vitesse (5) a une plus petite largeur de sillon et une plus grande profondeur vers un fond de sillon que l'autre.
     
    3. Dispositif de distribution variable selon la revendication 2, dans lequel :
    le sillon de tête côté diminution de vitesse (5) a une plus petite largeur de sillon et une plus grande profondeur vers un fond de sillon que le sillon de tête côté augmentation de vitesse (4).
     
    4. Dispositif de distribution variable selon l'une quelconque des revendications 1 à 3, dans lequel :
    la cheville de commutation côté augmentation de vitesse (8p) et la cheville de commutation côté diminution de vitesse (9p) sont agencées à une même position axiale et à des positions séparées l'une de l'autre dans une direction circonférentielle du porte-came (3).
     




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    Cited references

    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description