JP2007092752A - Force transmitting device with hydraulic valve looseness compensating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure starting stage and warming stage of an internal combustion engine without valve driving mechanism noise by improving a force transmitting device, which is provided with a hydraulic valve looseness compensating device for a valve driving mechanism of an internal combustion engine, to use a sufficiently large hydraulic medium reservoir capable of perfectly preventing leakage as a working chamber of a vale looseness compensating device. <P>SOLUTION: A hydraulic medium overflow part 29 is always extended, facing the highest position of an end surface 22 of a compensation piston 18 with a view from land surveying point, and the end surface 22 of the compensation piston 18 and an inside surface 23 of a bottom part 11 co-work for hydraulic sealing work in parts except the hydraulic medium overflow part 29. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a force transmission device including a hydraulic valve play compensation device for a valve drive mechanism of an internal combustion engine, the force transmission device being an outer peripheral surface of the internal combustion engine with respect to the direction of gravity. The force transmission device is guided in a tilted guide so as to be movable in the longitudinal direction, and the force transmission device has, on the end surface, a bottom portion that is prevented from rotating around the longitudinal axis of the guide, and the bottom portion is an inner surface. The flat end surface of the compensation piston of the valve play compensating device is supported by the surface, and the hydraulic medium overflow portion is provided on the inner side surface, and the hydraulic medium overflow portion supplies the hydraulic medium supply of the internal combustion engine. The hydraulic medium front chamber connected to the section is connected to a hydraulic medium reservoir extending inside the compensation piston, and the hydraulic medium reservoir serves to supply the hydraulic medium supply to the working chamber of the valve play compensation device. For the type that works for.

  The function of the hydraulic valve play compensation device, which is necessary in all operating conditions, including stop and start of the internal combustion engine, is largely related to the characteristics of the hydraulic medium reservoir, which is compensated for valve play compensation. A hydraulic medium must be sufficiently supplied to the working chamber which expands during the compensation movement of the device. A particularly critical operating condition in this context is the start-up process of the internal combustion engine when cold, usually with one or more gas exchange valves open, and in such cases The compensator piston of the associated piston play compensator is partly or under pressure when the hydraulic medium is pushed away from the working chamber under the force of the gas exchange valve spring and depending on the length of time of the stop state of the internal combustion engine. It has been completely lowered. The hydraulic medium pump also delivers no or insufficient hydraulic medium volume flow to the compensating piston during the start-up process, so the working position from the large hydraulic medium demand in the working chamber, ie the lowered position of the compensating piston, Completely covering the large hydraulic medium demand of the working chamber during the expansion of the working chamber into the hydraulic chamber is almost the only challenge. If the hydraulic medium reservoir has an insufficient size or is only insufficiently filled, bubbles are forced into the working chamber. The results when the working chamber contains bubbles for the valve drive mechanism function during start-up and operation of the internal combustion engine are known to those skilled in the art, and in particular its closing action based on the high contact speed of the gas exchange valve Sometimes it is unpleasantly recognized as a tappet noise of a so-called valve drive mechanism.

  Thus, a hydraulic valve play compensator that functions satisfactorily requires a hydraulic medium reservoir that is sufficiently large and sufficiently filled. When designing the hydraulic medium reservoir, it is advantageous if the volume of the hydraulic medium reservoir is several times the volume of the working chamber, and thus dimensioned to the working chamber under all operating conditions of the internal combustion engine. Inadvertent suction of air bubbles can be reliably avoided. However, such sizing conflicts with the goal setting to further reduce the structural space and / or mass of the force transmission device or the goal setting to further enhance the function of the force transmission device if the structural space does not change. Become. In the latter case, in particular, the following force transmission device, that is, a switchable tappet is formed, and various cam strokes are selectively transmitted to the gas exchange valve according to the switching state of the connecting means. A force transmission device that can and / or completely eliminate the stroke of a particular cam is mentioned. For this purpose, the tappet portions that are slidable in the longitudinal direction and are connectable to each other are arranged so as to be nested inside and outside each other, so that the outside of the tappet and the connection geometry remain substantially unchanged. With such a configuration, it is possible to reduce the structural space of the hydraulic valve play compensator and thus the volume of the hydraulic medium reservoir closed by the compensation piston. Insufficient supply of hydraulic medium in the working chamber is caused.

  The precondition is that the hydraulic medium reservoir, as well as the fully filled hydraulic medium reservoir, is well protected against hydraulic medium loss due to outflow. Satisfying this requirement is that, in particular, the force transmission device is tilted with respect to the direction of gravitational action and incorporated in the internal combustion engine, so that most of the hydraulic medium in the hydraulic medium reservoir flows out into the hydraulic medium front chamber. Difficult if possible.

  On the basis of DE 19603915 A1, which is a force transmission device of the type mentioned at the beginning, a force transmission device formed as a tappet is known. In this known configuration, the tappet is incorporated in a guide of an internal combustion engine that is tilted with respect to gravity so as not to rotate, and the hydraulic medium overflow section is defined by a hydraulic medium defined by a compensation piston. Between the reservoir and the hydraulic medium front chamber, it extends opposite the geodesic lowest point of the end face of the compensation piston. Therefore, in the stopped internal combustion engine and the non-pressure hydraulic medium supply unit, the hydraulic medium flowing out from the hydraulic medium reservoir to the hydraulic medium front chamber is caused by the filling level of the hydraulic medium in the hydraulic medium front chamber. It can only be avoided if it is at least at the level of the hydraulic medium overflow. The precondition for this is also a supply hole that extends farther in the housing of the tappet and connects the hydraulic medium supply part to the hydraulic medium front chamber, and the position of this supply hole is the hydraulic medium front chamber Prevents from becoming empty. However, in this case, when the overlap is lacking, the pressure loss inside the hydraulic medium supply unit based on the free outflow of the hydraulic medium from the hydraulic medium supply unit to the guide is caused by the tappet that is moved in the longitudinal direction. In order to avoid this, the above specification proposes a ring segment extending from the bottom of the tappet. This ring segment is desired to cover the hydraulic medium supply section even during the maximum stroke of the tappet. However, as will be apparent to those skilled in the art, such ring segments are remarkably cumbersome in manufacturing technology, require correspondingly high manufacturing costs, and undesirably increase the weight of the tappet. Furthermore, such a solution often requires moving the hydraulic medium passage, which extends low in the guide, to a higher position corresponding to the supply hole. However, this is not possible in the internal combustion engine design, which is usually completely or at most slightly changeable.

Furthermore, DE 3500425A1 discloses a tappet provided with a hydraulic medium reservoir outflow prevention device, which tappet is also provided on a guide which is also inclined with respect to the direction of gravity action. The movement is not prevented. The outflow prevention device is formed by arranging a supply passage opening to the hydraulic medium front chamber so as to face the hydraulic medium overflow portion communicating with the hydraulic medium reservoir in a diametrical direction. In the tappet position where the hydraulic medium overflow occupies the highest geodetic position and the opening of the supply passage occupies the lowest geodetic position, and vice versa. It is also fully effective in tappet positions where the hydraulic medium overflow occupies the lowest geodesic position and the supply passage opening occupies the highest geodesic position. In the former case, the outflow of the hydraulic medium from the hydraulic medium reservoir is blocked by the occupying hydraulic medium overflow itself, whereas in the latter case, the hydraulic pressure is almost completely filled. The medium front chamber prevents the hydraulic medium from flowing out of the hydraulic medium reservoir. However, outflow of hydraulic medium from the hydraulic medium reservoir cannot be prevented at all other intermediate positions other than these two extreme positions of the tappet. This is because at the intermediate position, the hydraulic medium overflow or the supply passage opening is away from the geodetically optimal position for outflow prevention.
DE196603915A1 DE3500425A1

  The object of the present invention is therefore to improve the force transmission device of the type mentioned at the outset and to eliminate the disadvantages of the prior art as described above, i.e. the working chamber of the valve play compensator is at any time. A sufficiently large hydraulic medium reservoir, which is almost completely prevented from spilling, can be used, so that the start-up and warm-up phases of the internal combustion engine can be ensured, especially without valve drive noise It is.

  In order to solve this problem, in the configuration of the present invention, the hydraulic medium overflow portion always extends facing the geodesic highest position of the end surface of the compensation piston, and the end surface of the compensation piston and the inner surface of the bottom portion However, it is designed to cooperate hydraulically with a sealing action except for the hydraulic medium overflow portion.

  Another advantageous configuration of the invention is described in claims 2 and below.

  By positioning the hydraulic medium overflow in this way, the maximum possible filling level of the hydraulic medium reservoir is ensured even in a force transmission device that is tilted with respect to the direction of gravity action and built into the internal combustion engine. As a result, the working chamber is always able to utilize a sufficiently large hydraulic medium volume that prevents the suction of bubbles. Furthermore, since the filling level of the hydraulic medium reservoir is almost independent of the filling level of the hydraulic medium front chamber when the internal combustion engine is stopped, the function of the valve play compensation device is completely in the hydraulic medium supply section or guide. Even in the evacuated hydraulic medium front chamber, it is not damaged.

  The force transmission device formed in this way can be subjected to a force load in the longitudinal direction by an arbitrary valve drive mechanism member, but the force transmission device is formed as a tappet in an advantageous configuration of the present invention, in this case outside the bottom. The side acts as a cam contact surface. This outer surface can be formed in the form of a cylindrical section as viewed in the cam rotation direction. Unlike the flat tappet bottom, the cam contact surface thus formed allows a significant diameter reduction of the tappet. This is because the pressing angle, which corresponds to the cam movement and determines the tappet diameter, is significantly smaller during the same stroke of the tappet than at the bottom of the flat tappet.

  Finally, the tappet can be configured to be switchable to transmit different cam strokes. In this case, the outer peripheral surface is part of the outer part, in which the inner part that receives the valve play compensation device is subjected to the force of the lost motion spring that is tightly arranged between the outer part and the inner part. On the other hand, it is supported so as to be slidable in the longitudinal direction, and can be coupled to the outer part in a form coupling manner in the transmission direction using a locking mechanism. Such tappets are known, for example, based on DE 4492633 C1, in which case it is always advantageous in terms of construction space and function to further reduce the diameter of the inner part and the height of the valve play compensation device. The volume reduction of the hydraulic medium reservoir that inevitably occurs in this way can be particularly advantageously combined with the positioning of the hydraulic medium overflow according to the invention, so that the working chamber Even when mounted tilted, a sufficient hydraulic medium volume can still be utilized.

  An advantageous embodiment of the invention will now be described with reference to the drawings.

  FIG. 1 shows a force transmission device 2 formed as a tappet 1 for a valve drive mechanism of an internal combustion engine. The tappet 1 is guided on the outer peripheral surface 3 so as to be movable in the longitudinal direction in a guide 5 inclined with respect to the acting direction of the gravity 4, and the tappet 1 is also camshaft with respect to a gas exchange valve (not shown). It is designed to be switchable to transmit different cam strokes (also not shown) in relation to the operating point. For this purpose, the inner part 7 is slidable in the outer part 6 in the longitudinal direction against the force of the lost motion spring (Lost-Motion-Feder) 8 which is tightened between the outer part 6 and the inner part 7. And can be coupled to the outer part 6 in the transmission direction by means of the locking mechanism 9 in a formschluessig. The bottom portion 11 of the inner portion 7 extending along the end surface 10 of the tappet 1 and the bottom portion 12 of the outer portion 6 have outer surfaces 13 and 14 formed in a cylindrical section shape. 13 and 14 serve as cam contact surfaces 15 and 16. Not only for the hydraulic pressure supply described later, but also based on the cam contact surfaces 15 and 16 thus formed, it is necessary to prevent the tappet 1 from turning around its longitudinal axis. is there. Such a rotation-preventing configuration is not shown in the illustrated longitudinal sectional view, but for that purpose, a rotation-preventing needle known in the prior art can be provided. The guide 5 extends in a longitudinal groove having a complementary shape beyond the outer peripheral surface 3 of the guide 5.

  The inner part 7 of the tappet 1 serves to receive a hydraulic valve play compensation device 17 which has a working chamber 19 defined by a hollow cylindrical compensation piston 18. The working medium 19 is supplied with a hydraulic medium via a check valve 21 from a hydraulic medium reservoir 20 extending inside the compensation piston 18. The compensation piston 18 has a circular ring shape and a flat end surface 22 which is supported on the inner surface 23 of the bottom 11 of the inner part 7 on the surface. The valve play compensation device 17 is connected to a hydraulic medium supply device of the internal combustion engine using a hydraulic passage 24 that cuts the guide 5. The hydraulic medium from the hydraulic passage 24 first reaches the inside of the hydraulic medium front chamber 26 via the supply hole 25 extending on the outer peripheral surface 3, and this hydraulic medium front chamber 26 is on the one hand of the outer portion 6. It is defined by a bottom 12 and a spring-supporting sheet metal 27 and further has a ring chamber 28 that surrounds the compensation piston 18 in the inner part 7. The hydraulic connection of the hydraulic medium reservoir 20 to the hydraulic medium front chamber 26 is finally made via a hydraulic overflow section (Hydraulikmitteluebertritt) 29 extending along the inner surface 23 of the bottom 11. The pressure overflow part 29 is formed as a circular indentation part. In this case, the hydraulic pressure overflow portion 29 is always located opposite to the geodesic highest position of the end face 22 of the compensation piston 18. This is because the inner part 7 is also prevented from rotating about its longitudinal axis with respect to the outer part 6 by known means not shown. The end face 22 of the compensation piston 18 and the inner side surface 23 of the bottom 11 cooperate with each other outside the hydraulic overflow part 29, that is, other than the hydraulic medium overflow part 29, in a hydraulically sealing manner. The medium reservoir 20 is prevented from flowing into the hydraulic medium front chamber 26 during the stop phase of the internal combustion engine. In this case, the hydraulic medium reservoir 20 ideally has a maximum possible filling level 30 indicated symbolically.

  The control of the lock mechanism 9 is performed using a hydraulic medium whose pressure is adjusted from the second hydraulic pressure passage 31 separately from the hydraulic pressure supply to the valve play compensating device 17. The second hydraulic pressure passage 31 is connected to the hydraulic pressure chamber 33 separated from the hydraulic pressure medium front chamber 26 via another supply hole 32 in the outer peripheral surface 3 of the outer portion 6, and this hydraulic pressure chamber From 33, the hydraulic medium reaches the lock mechanism 9. It is necessary to prevent the tappet 1 from rotating about its longitudinal axis even based on this dual hydraulic supply mode.

1 is a longitudinal sectional view showing a force transmission device according to the present invention, taking as an example a switchable tappet incorporated in a guide of an internal combustion engine;

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Tappet, 2 Force transmission device, 3 Outer peripheral surface, 4 Gravity, 5 Guide, 6 Outer part, 7 Inner part, 8 Lost motion spring, 9 Locking mechanism, 10 End face, 11 Bottom part, 12 Bottom part, 13 Outer side face, 14 Outside Side surface, 15 Cam contact surface, 16 Cam contact surface, 17 Valve play compensation device, 18 Compensation piston, 19 Working chamber, 20 Hydraulic medium reservoir, 21 Check valve, 22 End surface, 23 Inner side surface, 24 Hydraulic passage, 25 Supply hole, 26 Hydraulic medium front chamber, 27 Spring-supported metal thin plate, 28 Ring chamber, 29 Hydraulic medium overflow section, 30 Filling level, 31 Hydraulic passage, 32 Supply hole, 33 Hydraulic chamber

Claims (4)

  A force transmission device (2) provided with a hydraulic valve play compensation device (17) for a valve drive mechanism of an internal combustion engine, the force transmission device (2) having an outer peripheral surface (3), In the guide (5) inclined with respect to the direction of action of the gravity (4), it is guided so as to be movable in the longitudinal direction, and the force transmission device (2) is guided to the end surface (10) in the longitudinal direction of the guide (5). A bottom portion (11) that is prevented from rotating about an axis, the bottom portion (11) is an inner surface (23), and the compensation piston (18) of the valve play compensator (17) is flat; The end surface (22) is supported by the surface, and the inner side surface (23) has a hydraulic medium overflow portion (29), and the hydraulic medium overflow portion (29) supplies the hydraulic medium of the internal combustion engine. The hydraulic medium front chamber (26) connected to the section extends through the inside of the compensation piston (18). In the type connected to the reservoir (20), the hydraulic medium reservoir (20) serves to supply the hydraulic medium to the working chamber (19) of the valve play compensator (17). The overflow part (29) always extends opposite the geodesic highest position of the end face (22) of the compensation piston (18), and is within the end face (22) and bottom part (11) of the compensation piston (18). The force transmission device having a hydraulic valve play compensating device, wherein the side surface (23) cooperates with a sealing action hydraulically except for the hydraulic medium overflow portion (29).   2. The force transmission device according to claim 1, wherein the force transmission device (2) is formed as a tappet (1) and the outer surface (13) of the bottom (11) serves as a cam contact surface (15).   The force transmission device according to claim 2, wherein the cam contact surface (15) is formed in a cylindrical section shape when viewed in the cam rotation direction.   The tappet (1) is formed to be switchable to transmit different cam strokes, the outer peripheral surface (3) is part of the outer part (6), and in the outer part (6) there is a valve The inner part (7) receiving the play compensation device (17) is longitudinally opposed to the force of the lost motion spring (8) which is arranged tightly between the outer part (6) and the inner part (7). 3. The force transmission device according to claim 2, wherein the force transmission device is slidably supported and can be coupled to the outer part (6) in a shape coupling manner in the transmission direction by means of a locking mechanism (9).

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