Patent Publication Number: US-11384662-B2

Title: Valve assembly for controlling a camshaft timing apparatus

Description:
This nonprovisional application is a continuation of International Application No. PCT/EP2017/069960, which was filed on Aug. 7, 2017, and which is herein incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a valve assembly for controlling an apparatus for camshaft timing adjustment being driven by a hydraulic pump. The valve assembly comprises a valve body with a first control port, a second control port, a high pressure port and a low pressure port. The valve assembly has a first state for enabling a flow of a hydraulic fluid from the high pressure port to the first control port and from the second control port to the low pressure port, respectively. The valve assembly has a second state for enabling a flow of the hydraulic fluid from the high pressure port to the second control port and from the first control port to the low pressure port, respectively. Further, the invention relates to a hydraulic pump connected to such a valve assembly and an apparatus for camshaft timing adjustment having a hydraulic pump. 
     Description of the Background Art 
     In the art, different configurations of apparatuses for camshaft timing adjustment are known. Apparatuses for camshaft timing adjustment, which can as well be referred to as a camshaft timing apparatuses, are widely used for adjusting dynamically the opening and closing times of intake and outtake valves of a combustion engine during its operation. 
     Most combustion engines comprise a crankshaft for transforming a translational movement of cylinder pistons into a rotational movement and a camshaft for operating intake and outtake valves of the respective cylinders. The camshaft defines the opening and closing times of the valves relative to each other and is typically driven by the crankshaft via a transmission, mostly via a gear drive, a belt drive, a chain drive or the like. For instance, a drive disc like a sprocket or a pulley may be coupled to the camshaft and engaged with a corresponding gear of the crankshaft such, that by driving the drive disc, the camshaft rotates according to the crankshaft. In four stroke engines (i.e. Otto-type engines) the camshaft is usually driven to rotate with half the speed of the crankshaft. 
     Accordingly, apparatuses for camshaft timing adjusting have to allow for dynamically adjusting the angular relation between the rotational position of the camshaft and the rotational position of the crankshaft during operation of the combustion engine. For example the angular relation may be adjusted depending on a throttle position and/or the rotational speed of the crankshaft which is usually measured in RPM (Rotations Per Minute). As the angular relationship defines the point of time for opening and closing of each valve relative to a particular position of an associated cylinder piston, changing the angular relation between the crankshaft and the camshaft is also referred to as ‘timing’. 
     A possibility to allow for adjusting the timing of the camshaft relative to the crankshaft during operation of the combustion engine is to use an apparatus for camshaft timing adjusting comprising a drive disc being configured to be coupled to the crankshaft and a hub being arranged within the drive disc or vice versa. The drive disc and the hub define a common rotational axis and rotationally support each other for a relative rotation about the common rotational axis. The hub may be torque-proof coupled to the camshaft. Thus, by adjusting the angular relation of the hub relative to the drive disc, the angular relation between the camshaft and the crankshaft and, correspondingly, the timing of the valves may be adjusted. 
     To enable an adjustment of the angular relation between the hub and the drive disc it has been suggested to provide an apparatus for camshaft timing adjustment with one or more adjusting chambers defined by the drive disc and the hub as well as one or more vanes. The vanes are accommodated in the adjusting chambers and separate them each into a first sub-chamber and a second sub-chamber. A chamber should be understood herein as a cavity or hollow space which is enclosed by inner surfaces of a body, e.g. by casing walls or the like. 
     By pumping a working fluid, for instance a hydraulic oil, from the first sub-chambers to the second sub-chambers, the vanes may be angularly displaced within and relative to the adjusting chambers, which results in an angular adjustment of the hub relative to the drive disc. Vanes and adjustment chambers, thus, can be considered as a hydraulic drive of the apparatus for camshaft timing adjustment. 
     Pumping of the working fluid between the first and second sub-chambers is usually achieved by means of a hydraulic pump. The hydraulic pump is fluidly connected to the first and second sub-chambers of the apparatus for camshaft timing adjustment and configured to pump the working fluid between the first and second sub-chambers, thereby swivelling the hub relative to the drive disc. Only to avoid any misunderstanding, swivelling indicates a rotation of the hub and the drive disc relative to each other about the common rotational axis. The term is used to indicate that the rotation is limited to a certain angle of relative rotation. The limitation is due to constructional details of the particular apparatus, e.g. the dimensions of the adjustment chambers and the vanes. 
     The hydraulic pump may have a high pressure pump chamber, a low pressure pump chamber and a pump for pumping the working fluid from the low pressure pump chamber to the high pressure pump chamber. Each pump chamber of the hydraulic pump is fluidly connected to the first sub-chambers and the second sub-chambers. The hydraulic pump is typically disposed separate from the camshaft and driven by the crankshaft which reduces the available engine capacity. 
     To allow for selectively pumping the working fluid back and forth between the first sub-chambers and the second sub-chambers the apparatus for camshaft timing adjustment is provided with a valve assembly having a valve body and a valve actuator for controlling a fluid flow between the pump chambers and the sub-chambers. The valve actuator may be mechanically coupled to a valve control unit. 
     The valve assembly has a first state for enabling a flow of the working fluid from the high pressure port to the first control port and from the second control port to the low pressure port, respectively. In the first state the high pressure pump chamber is fluidly connected to the first sub-chambers and the low pressure pump chamber is fluidly connected to the second sub-chambers. When the valve assembly is in the first state the angular relation between the drive disc and the hub changes into a first direction. 
     The valve assembly has a second state for enabling a flow of the working fluid form the high pressure port to the second control port and from the first control port to the low pressure port, respectively. In the second state the high pressure pump chamber is fluidly connected to the second sub-chambers and the low pressure pump chamber is fluidly connected to the first sub-chambers. When the valve assembly is in the second state the angular relation between the drive disc and the hub changes into a second direction which is opposite to the first direction. As a result, the valve assembly selectively allows for swivelling forth and swivelling back of the hub relative to the disc drive. 
     Exemplary apparatuses for camshaft timing adjustment of this type are disclosed e.g. in U.S. Pat. No. 8,291,876 B1 and U.S. Pat. No. 6,453,859 B1. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a valve assembly allowing for a compact, reliable and light weight apparatus for camshaft timing adjustment which can be manufactured at reduced cost and on the other hand provides for fast adjustments of the crankshaft timing. 
     In an exemplary embodiment a valve assembly is provided wherein the valve body comprises a central actuating through-hole extending axially through the valve body defining an axial direction. The first and second control ports are preferably arranged on axially opposite sides of the valve body and connected to each other by the central actuating through-hole. The valve assembly further comprises a valve actuator preferably having a pin-like valve needle with an actuating section being arranged central and axially displaceable in the actuating through-hole of the valve body. The valve actuator may be in a first axial position in the first state of the valve assembly and in a different second axial position in the second state of the valve assembly. 
     The valve body can comprise a high pressure channel extending from the high pressure port for fluidly connecting the high pressure port to the hydraulic pump and a low pressure channel extending from the low pressure port for fluidly connecting the low pressure port to the hydraulic pump. Integrating the high and low pressure channels into the valve body is efficient if high pressure sources and low pressure sources are positioned immediately adjacent to the valve body. 
     The high pressure port may be configured as a first internal valve chamber of the valve body and the low pressure port may be configured as a second internal valve chamber of the valve body. The first and second internal valve chambers are preferably juxtaposed in the axial direction. First and second internal valve chambers allow for easily parallelizing more than one high pressure source and more than low pressure source, respectively. Thus, high pressure ports and low pressure ports are provided which can be multiply connected. 
     The first internal valve chamber may have an elongate section extending radially wherein the associated high pressure channel opens into an end region of the elongate section. Alternatively or additionally, the second internal valve chamber may have an elongate section extending radially wherein the associated low pressure channel opens into an end region of the elongate section. 
     The first internal valve chamber preferably has a plurality of elongate sections each associated with a high pressure channel and preferably the second internal valve chamber has a plurality of elongate sections each associated with a low pressure channel. 
     The first internal valve chamber can have exactly two elongate sections being arranged collinear and the associated high pressure channels open into radially opposite end regions of the elongate sections and/or the second internal valve chamber has exactly two elongate sections being arranged collinear and the associated low pressure channels open into radially opposite end regions of the elongate sections. 
     The elongate sections of the first internal valve chamber and the elongate sections of the second internal valve chamber may extend parallel. The high pressure channels and the low pressure channels preferably open from opposite sides into the elongate sections of the associated internal first and second internal valve chambers, respectively. Parallel elongate sections of the first and second interval valve chambers leads to a simple and symmetrical structure of the valve assembly which can easily manufactured. 
     The valve assembly can comprise two high pressure ports and to low pressure ports, wherein the corresponding internal valve chambers are arranged in a first pair and a second pair. Each pair may comprise a first internal valve chamber and a second internal valve chamber being separated by a separation wall. The first and second pairs may be juxtaposed in the axial direction. The axial sequence of the first and second internal valve chambers is preferably different between the pairs. This pairwise configuration of the first and second internal valve chambers corresponds to the configuration of the first and second control ports of the valve assembly. 
     The valve body may comprise a first annular channel surrounding the first pair and a second annular channel surrounding the second pair of internal valve chambers. Each annular channel preferably has two axial channel sections and two radial channel sections connecting corresponding axial ends of the axial channel sections. In a preferred embodiment each outer axial channel section is configured as a groove extending in the corresponding axial surface of the valve body, the grooves being the first and second control ports, respectively. This allows for a short connection of the annular channels to the first and second internal valve chambers which can easily be manufactured. 
     The central actuating through-hole may be fluidly connected with the first internal valve chambers, the second internal valve chambers and the radial channel sections of the first and second annular channels. Thus, the central actuating through-hole provides fluid connections between the high pressure port and the low pressure port of the valve assembly, the first and second internal valve chambers and the first and second annular channels, respectively. 
     The actuating section can comprise a plurality of annular protrusions being juxtaposed in the axial direction and defining axial clearances between each other. The annular protrusions may be arranged and configured to selectively and exclusively open in the first axial position of the valve actuator fluid connections between the first internal valve chamber of the first pair and the first annular channel as well as the second internal valve chamber of the second pair and the second annular channel, respectively. In the second axial position of the valve actuator fluid connections may be correspondingly opened between the first internal valve chamber of the second pair and the second annular channel as well as the second internal valve chamber of the first pair and the first annular channel, respectively. The axial length and the radial width of the annular protrusions as well as the axial length of the clearances correspond to the axial configuration of the first and second pairs with the first and second internal valve chambers therein, of the first and second annular channels and the axial distances between these elements. 
     The valve assembly can have a third state for enabling a flow of the hydraulic fluid from the first internal valve chambers to the second internal valve chambers and fluidly separating the first control port and the second control port from the internal valve chambers. In the third state of the valve assembly the valve actuator may be in a third axial position different from the first and second positions opening a connection between the first internal valve chambers and the second internal valve chambers while closing the first and second annular channels. In other words, by selecting the third position of the valve actuator which may be referred to as a neutral position, a short circuit fluid connection is established wherein the hydraulic fluid is not pumped between the first and second control ports of the valve assembly. 
     Furthermore, a hydraulic pump having a valve assembly is provided. The valve assembly can be arranged within the hydraulic pump. The integration of the valve assembly into the hydraulic pump leads to a very compact structure and avoids a valve assembly separate from the hydraulic pump. 
     The hydraulic pump may have a stator, a rotor defining a common rotational axis extending in the axial direction, at least one low pressure pump chamber and at least one high pressure pump chamber. A high pressure channel may open into each high pressure pump chamber and a low pressure channel may open into the each low pressure pump chamber. The high pressure channel and the low pressure channel allow for connecting the at least one high pressure pump chamber and the at least one low pressure chamber to the high pressure ports and low pressure ports of the valve assembly, respectively. 
     The hydraulic pump can comprise a pump for pumping the hydraulic fluid from the at least one low pressure pump chamber to the at least one high pressure pump chamber. The pump may be supported by the stator or the rotor and configured for pumping the hydraulic fluid from the at least one low pressure pump chamber to the at least one high pressure pump chamber due to a rotation of the rotor relative to the stator about the common rotational axis. This configuration of a hydraulic pump is very simple and allows for small dimensions of the hydraulic pump in order to fit in the central through-hole of the hub. 
     The stator may comprise an internal gear being attached to the hub and the rotor may comprise a rotor body disposed within the internal gear. In a preferred embodiment the rotor body integrally comprises the valve body and is supported rotationally about the common rotational axis such that the teeth of the internal gear and peripheral surface sections of the rotor body abut to form a radial bearing. The internal gear of the hydraulic pump may either be integral with the hub or torque-proof secured to the hub, i.e. by a form fit, a tight fit, any permanent connection or even a combination of these. Preferably the tips of the teeth are configured to provide small peripheral surface sections which are complementary to the peripheral surface sections of the rotor body. 
     The pump is preferably a gear wheel being supported by the rotor body and/or engaged with the internal gear and having a rotational axis parallel to the common rotational axis. The gear wheel preferably has an at least essentially circular cylindrical envelope. This means that the tips of the teeth of the gear wheel define a circular cylindrical surface being centered on the rotational axis of the gear wheel. The gear wheel has a rotational axis being at least essentially parallel with the common rotational axis (maximum inclination angle ±30°, preferably ±20°, even more preferred ±10° or even better) ±2.5°. This eases manufacturing and enhances the life cycle of the apparatus. When the rotor body rotates relative to the internal gear, the gear wheel rotates relative to the rotor due to their engaging teeth. Thereby, the gear wheel and the rotor are counter-rotating, i.e. the gear wheel rotates in the counterclockwise direction when the rotor body rotates in the clockwise direction or vice versa. 
     In other words, the hydraulic pump is preferably an internal gear pump. However, different pump types as, for example, a vane cell pump or different pump designs may alternatively be used as long as they, at the same time, can be accommodated within the hub or the drive disc, can accommodate a valve assembly and can be fluidly connected to the first and second sub-chambers. 
     The rotor body preferably comprises two separating arms and two pumping arms extending in a radial direction and alternating in a circumferential direction and separating from each other two high pressure pump chambers and two low pressure pump chambers alternating in a circumferential direction. The two pumping arms each may support a bearing pin rotationally supporting a pump and defining a fluid passage between a high pressure pump chamber and an adjacent low pressure pump chamber. This optimizes the fluid flow between the low pressure pump chambers and high pressure pump chambers and eases manufacturing of the hydraulic pump. Again, at least essentially parallel means that a deviation from parallelism is smaller than or equal to ±30° (preferably ±20°, even more preferred ±10° or even better)±2.5°. Additionally, the rotational axes of the gear wheels are at least essentially parallel to the common rotational axis (maximum inclination angle of ±30°, preferably ±20°, even more preferred ±10° or even better) ±2.5°. As well the rotational axes of the gear wheels are preferably evenly spaced to the common rotational axis (relative distance deviation preferably within ±20%, even more within ±10% or even better within ±2.5%). Both measures simplify manufacture and increase lifetime as constructional imbalances of the hydraulic pump are reduced. 
     It is preferred that the separating arms integrally comprise the valve body. Particularly the elongate sections of the first and second internal valve chambers may be arranged in the separating arms, the axial channel sections of the annular channels being disposed spaced apart in the separating arms. This arrangement leads to a compact and integrated structure of the hydraulic pump and the valve assembly. 
     Further the invention provides an apparatus for camshaft timing adjustment. The apparatus comprises a drive disc and a hub rotationally supported relative to each other wherein the hub is arranged within the drive disc or vice versa, a vane being accommodated in an adjusting chamber defined by the drive disc and/or the hub and separating the adjusting chamber into a first sub-chamber and a second sub-chamber, wherein the vane is attached to the hub or the drive disc. Preferably an inventive hydraulic pump is arranged within the hub wherein the first control port is fluidly connected to the first sub-chamber and the second control port is fluidly connected to the second sub-chamber. This arrangement yields a very compact structure of the camshaft timing apparatus. 
     The drive disc may have a casing accommodating the hub, the casing comprising a casing wall and a casing lid axially closing the casing. For example, the casing may have a cylindrical casing wall which is centered with respect to the common rotational axis and axially protrudes from a base disc of the drive disc. The casing may be axially closed by a circular casing lid which is secured to the casing wall on the axially opposite side of the casing wall with respect to the base disc. Thus, the hub accommodated therein may be supported axially and radially. On the one hand, outer axial surface sections of the hub may abut on corresponding inner axial surface sections of the base disc and the casing lid, respectively, forming an axial bearing. On the other hand, outer peripheral surface sections of the hub may abut on inner peripheral surface sections of the casing wall forming a radial bearing. The base disc may have a peripheral external gear for engaging with a corresponding toothed drive belt or, alternatively, a drive chain and/or a cog wheel, all of which may be used to couple the apparatus to the crankshaft of the combustion engine. 
     The drive disc may comprise a plurality of separator. The separator may be configured as and/or comprise protrusions extending radially inward from the casing wall and providing at least one, preferably two or more adjusting chambers from each other in a circumferential direction. In case of more than one adjusting chamber the separator may separate neighboured adjustment chambers from each other. Preferably, the apparatus may comprise a plurality of vanes each extending radially outward from the hub into an associated adjusting chamber. The separator may thus have side faces providing circumferential boundaries of the adjusting chambers. If the separator are provided by protrusions being attached to or integrally formed with the drive disc, the apparatus can be kept very compact and thus small. Further precision is enhanced as well as assembly simplified. The protrusions do not necessarily have straight side faces. The side faces can be curved and/or inclined against the radial direction, but the radially extending protrusions should provide a radially extending barrier between two adjusting chambers being formed by or attached to the drive disk. The separator in some sense can be considered as spokes but they do not need to bear any radial load. In this picture, however, the side faces of two neighbored spokes would face each other. In between of the side faces of two neighbored protrusions there is an adjusting chamber. 
     A plurality of separator and a plurality of vanes as well allows for avoiding any dynamic imbalance of the drive disc and the hub, respectively. Of course, the separator may alternatively protrude radially outward from the hub, if the vanes extend radially inward from the casing wall in turn. 
     Exactly two vanes and two adjusting chambers are preferably provided, particularly forming pairs and being disposed on opposite sides of the common rotational axis, respectively. This is the simplest configuration of vanes and adjusting chambers without any dynamic imbalance of the drive disc and the hub, respectively. Such apparatuses for camshaft timing adjustment are particularly easy and economic in manufacture. More generally dynamic imbalance can be minimized if the n vanes and chambers are rotationally symmetric in a sense that any rotation around integer multiples of 360°/(n≥2) maps the vanes and the adjustment chamber onto themselves. 
     The first sub-chambers and the second sub-chambers may alternate in a circumferential direction. An alternating sequence of first and second sub-chambers provides a symmetric structure of the required fluid connections to the first and second sub-chambers. 
     The hub preferably defines a central through-hole accommodating the hydraulic pump. The central through-hole may be cylindrical for ease of manufacture. Additionally, arranging the hydraulic pump within the hub is very easy with a central through-hole defined in the hub. 
     The hub may comprise a first hub lid and a second hub lid axially closing the through-hole on opposite sides of the hub. The second hub lid preferably comprises a coupler configured to provide a torque-proof connection with a camshaft wherein the coupler and/or the camshaft extends through a central camshaft through-hole of the drive disc. The first and second hub lids may have multiple functions. On the one hand, they provide inner surface sections for forming an axial bearing with complementary surface sections of the hydraulic pump. On the other hand, they may axially close the high pressure pump chambers and the low pressure pump chambers of the hydraulic pump. Apart from that, the second hub lid allows for the camshaft of the combustion engine to be coupled to the hub. Thus, the first and second hub lids preferably are axially and rotationally secured to the hub. 
     The hub may comprise at least one, preferably two first adjusting channels being configured as grooves in a first axial surface of the hub each extending radially outward from a central through-hole of the first hub lid to a vane and each bending into a first peripheral direction to open into a first sub-chamber. The hub may further comprise at least one, preferably two second adjusting channels being configured as grooves in a second axial surface of the hub each extending radially outward from a central through-hole of the second hub lid to a vane and each bending into a second peripheral direction to open into a second sub-chamber. The first and second adjusting channels preferably have straight sections formed in the first and second hub lids, respectively. In other words, the first and second sub-chambers of the apparatus for camshaft timing adjustment may be fluidly connected to the hydraulic pump via a central through-hole in the first and second hub lids and via the first and second adjusting channels configured in the first and second hub lids as well as in the axial surfaces of the vanes, respectively. This configuration of the fluid connection between the hydraulic pump within the hub and the first and second sub-chambers defined by the drive disc and the hub is very easy to manufacture and also reliable during operation. 
     The stator of the hydraulic pump can be integral with and/or torque-proof connected to the hub and/or the pump is supported by the rotor. Alternatively of additionally, the pump may be supported by the rotor. Of course, the pump may alternatively be supported by the stator. It has to be emphasized, that the terms ‘rotor’ and ‘stator’ only indicate a relative rotation of these two components of the hydraulic pump. Therefore, the rotor might be integral with or torque-proof connected to the hub instead. 
     The valve actuator may have an operating section extending through the central through-hole of the first hub lid, and a head at its outer free end. The valve actuator may be axially coupled to a valve control unit via the head. Thereby, the head may provide axial and radial bearing surface sections for allowing the valve actuator to rotate at a different angular speed than an interface of the valve control unit providing complementary surface sections. 
     The apparatus preferably comprises a torque transmission extending through a central torque transmitting trough-hole of the casing lid and being torque-proof connected to the rotor for establishing a relative rotation between the rotor and the stator. Thus, by securing the torque transmission to a static part, i.e. a non-rotating part of the combustion engine, the hydraulic pump is exclusively and immediately driven by a rotation of the hub or the drive disc relative to the torque transmission. In other words, the hydraulic pump can immediately be driven by the camshaft without imposing any immediate load on the crankshaft. The torque transmission is preferably configured as a bolt, e.g. as cylindrical bolt. 
     The torque transmission may define a central operating through-hole extending axially which is penetrated by the operating section of the valve actuator. This central operating through-hole preferably has a cylindrical shape with a diameter which, at the same time, rotationally supports the operating section of the valve actuator and seals the casing of the drive disc against loss of the hydraulic fluid. 
     The torque transmission may extend through the central torque transmitting through-hole of the casing lid and the central through-hole of the first hub lid. The torque transmission preferably has a coupler disposed at an outer end and a connector disposed at an opposite inner end, the connector being configured to establish the torque-proof connection between the torque transmission and the rotor body. 
     The connector may be configured as a pin-like protrusion being disposed excentrically and extending axially from the inner free end, and the rotor body may comprise a complementary recess formed in the axial surface and being engaged by the connector. This is a very simple measure to provide a torque-proof coupling between two parts which abut axially and rotate about a common rotational axis. 
     The connector may be configured as a plurality of protrusions being disposed around the operating through-hole, preferably two protrusions disposed on opposite sides of the operating through-hole, the rotor body comprising corresponding recesses. Providing more than a single protrusion allows for applying the torque more symmetrically. Of course, any different connector may be used as well. 
     The coupler may be configured as a hexagonal head. Alternatively, any other suitable structure may be provided as long as it allows for rotationally securing the torque transmission to a static part. 
     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes, combinations, and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein: 
         FIG. 1  shows an exploded perspective view of a camshaft timing apparatus according to an embodiment of the present invention. 
         FIG. 2  shows a perspective view of the drive disc of the camshaft timing apparatus according to the embodiment shown  FIG. 1 . 
         FIG. 3  shows a perspective view of the casing lid of the camshaft timing apparatus according to the embodiment shown  FIG. 1 . 
         FIG. 4  shows an axial front view of the partially assembled camshaft timing apparatus according to the embodiment shown in  FIG. 1 . 
         FIG. 5 a    shows a schematic axial front view of the partially assembled camshaft timing apparatus according to the embodiment shown in  FIG. 1 . 
         FIG. 5 b    shows the view of  FIG. 5 a    with indications of rotational directions and pressure situation during operation. 
         FIG. 6  shows a perspective view of the hub of the camshaft timing apparatus according to the embodiment shown  FIG. 1 . 
         FIG. 7  shows a perspective view of a gear wheel of the camshaft timing apparatus according to the embodiment shown  FIG. 1 . 
         FIG. 8  shows a perspective view of the rotor body of the camshaft timing apparatus according to the embodiment shown  FIG. 1 . 
         FIG. 9  shows a perspective view of a bearing pin of the camshaft timing apparatus according to the embodiment shown  FIG. 1 . 
         FIG. 10  shows a perspective view of a first hub lid of the camshaft timing apparatus according to the embodiment shown  FIG. 1 . 
         FIG. 11  shows a perspective view of second hub lid of the camshaft timing apparatus according to the embodiment shown  FIG. 1 . 
         FIG. 12  shows a perspective view of the valve actuator of the camshaft timing apparatus according to the embodiment shown  FIG. 1 . 
         FIG. 13  shows a circuit diagram of the valve assembly of the camshaft timing apparatus according to the embodiment shown  FIG. 1 . 
         FIG. 14  shows a perspective cross-sectional view of the rotor body shown in  FIG. 8  with the valve actuator shown in  FIG. 12  in a first position. 
         FIG. 15  shows a perspective cross-sectional view of the rotor body shown in  FIG. 8  with the valve actuator shown in  FIG. 12  in a second position. 
         FIG. 16  shows a perspective cross-sectional view of the rotor body shown in  FIG. 8  with the valve actuator shown in  FIG. 12  in a third position. 
         FIG. 17  shows a perspective view of the torque transmission of the camshaft timing apparatus according to the embodiment shown  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows an exploded view of the components of an apparatus for camshaft timing adjustment, as well referred to as camshaft timing apparatus  1 . The apparatus  1  comprises a drive disc  10  and a hub  50 . The drive disc  10  is configured to be connected to a crankshaft of a combustion engine. The hub  50  is configured to be torque-proof coupled to a camshaft of the combustion engine. The drive disc  10  and the hub  50  define a common rotational axis  2  and are rotationally supported relative to each other allowing for a rotating, i.e. for a swivelling movement of the hub  50  relative to the drive disc  10  about the common rotational axis  2 . Correspondingly, an angular relation between the crankshaft and the camshaft of the combustion engine can be adjusted by swivelling the hub  50  relative to the drive disc  10 . 
     As can be seen best from  FIGS. 2 and 3 , the drive disc  10  has a circular base disc  11 , a cylindrical casing wall  21  and a circular casing lid  22  which form a casing  20 . The base disc  11  has a plurality of teeth  13  forming a peripheral external gear for engaging with a corresponding toothed drive belt or, alternatively, a drive chain and/or a cog wheel, all of which may be used to couple the apparatus  1  to the crankshaft of the combustion engine. 
     The casing wall  21  is integral with the base disc  11 , centered with respect to the common rotational axis  2  and axially protrudes from the base disc  11 . The casing lid  22  is secured to the casing wall  21  axially opposite to the base disc  11  and closes the casing  20  axially. 
     The hub  50  is arranged within the drive disc  10  and accommodated in the casing  20 . The drive disc  20  and the hub  50  are rotationally supported relative to each other axially and radially via axial and radial bearings enabling the hub  50  to swivel relative to the drive disc  10 . On the one hand, outer axial surface sections of the hub  50  abut on corresponding inner axial surface sections both of the base disc  11  and the casing lid  22  forming axial bearings, respectively. On the other hand, outer peripheral surface sections  58  of the hub  50  abut on inner peripheral surface sections of the casing wall  21  forming a radial bearing. 
     The apparatus  1  further comprises two adjusting chambers  30  being defined by the drive disc  10  and the hub  50 , as can be best seen from  FIG. 4 . The drive disc  10  comprises a plurality of separator  33  being protrusions being formed by the drive disk  10 . The separator  33  extend radially inward from the casing wall  21  and provide a radially extending barrier between the two adjusting chambers  30  and separating the two adjusting chambers  30  from each other in a circumferential direction. The separator  33  have straight side surfaces  34  providing circumferential boundaries of the adjusting chambers  30 . 
     The apparatus  1  further comprises two vanes  57 . The vanes  57  are attached to the hub  50  and extend radially outward from the hub  50 . The vanes  57  are accommodated in an adjusting chamber  30  each and separate the associated adjusting chambers  30  into a first sub-chamber  31  and a second sub-chamber  32 , respectively. The first sub-chambers  31  and the second sub-chambers  32  alternate in a circumferential direction. 
     Each vane  57  is in touch both with the axial boundaries of the associated adjusting chamber  30  and with one of the radially outer boundary and the radially inner boundary of the associated adjusting chamber  30 , to thereby seal the sub-chambers  31 ,  32  from each other. Thus, each vane  57  limits a free (i.e. uncontrolled) flow of a hydraulic fluid between the first sub-chambers  31  and the second sub-chambers  32  of the associated adjusting chamber  30 . Accordingly, by pumping a fluid from the first sub-chamber  31  into the second sub-chamber  32 , each vane  57  can be swivelled relative to the associated adjusting chamber  30 . 
     Both adjusting chambers  30  and vanes  57  are disposed on opposite sides of the common rotational axis  2 , respectively. The depicted number of vanes  57  and corresponding adjusting chambers  30  is a preferred number, but only an example. Other numbers of vanes  57  and adjusting chambers  30  may be realized as well. 
     The apparatus  1  further comprises a hydraulic pump  100 , which is an internal gear pump shown best in  FIGS. 4 and 5   a ,  5   b . The hydraulic pump  100  is accommodated in the hub  50 , i.e. arranged in a central cylindrical through-hole  51  defined by the hub  50 . The hydraulic pump  100  has two high pressure pump chambers  101  and two low pressure pump chambers  102 . The high pressure pump chambers  101  and the low pressure pump chambers  102  alternate in a circumferential direction. Each pump chamber  101 ,  102  is fluidly connected to each first sub-chamber  31  and each second sub-chamber  32 . 
     The hydraulic pump  100  comprises a stator  104 , a rotor  105  and two pump  103  for pumping the hydraulic fluid from the low pressure pump chambers  102  to the high pressure pump chambers  101 . The stator  104  comprises an internal gear  106  which is integral with and, thus, torque-proof connected to the hub  50 , see  FIG. 6 . The rotor  105  comprises a rotor body  110  being disposed within the internal gear  106 . The rotor body  110  is supported rotationally about the common rotational axis  2  e.g. such that teeth  107  of the internal gear  106  and peripheral surface sections  111  of the rotor body  110  abut to form a radial bearing. The tips of the teeth  107  are configured to provide small peripheral surface sections which are complementary to the peripheral surface sections  111  of the rotor body  110 . 
     The pump  103  are configured for pumping the hydraulic fluid from the low pressure pump chamber  102  to the high pressure pump chamber  101  due to a rotation of the rotor  105  relative to the stator  104 . The pump  103  are gear wheels (see  FIG. 7 ) being supported by the rotor body  110 . The pump  103  are engaged with the internal gear  106  and have rotational axes  115  essentially parallel to the common rotational axis  2 . The pump  103  have a circular cylindrical envelope. This means that the tips of the teeth of the gear wheel define a circular cylindrical surface being centered on the rotational axis of the gear wheels. 
     When the rotor body  110  rotates relative to the internal gear  106 , the pump  103  rotate relative to the rotor body  110  due to their engaging teeth. Thereby, the pump  103  and the rotor body  110  are counter-rotating, i.e. the pump  103  rotate in the counterclockwise direction when the rotor body  110  rotates in the clockwise direction or vice versa. 
     As can be best seen from  FIG. 8 , the rotor body  110  may comprise e.g. two separating arms  112  and e.g. two pumping arms  113  extending in a radial direction. The arms  112 ,  113  alternate in a circumferential direction and separate from each other the high pressure pump chambers  101  and the low pressure pump chambers  102 . The two pumping arms  113  each support a bearing pin  114  shown in  FIG. 9 . The bearing pin rotationally supports a pump  103  and defining a fluid passage between a high pressure pump chamber  101  and an adjacent low pressure pump chamber  102 . The pump  103  have at least essentially parallel rotational axes  115 . As well the rotational axes  115  of the pump  103  are evenly spaced to the common rotational axis  2 . 
     The hub  50  comprises a first hub lid  52  and a second hub lid  53 . The first and second hub lids  52 ,  53  are shown in  FIGS. 10 and 11 , respectively. The first and second hub lids  52 ,  53  are axially and rotationally secured to the hub  50  and axially close the through-hole  51  on opposite sides of the hub  50 . The first and second hub lids  52 ,  53  have multiple functions. On the one hand, they provide inner surface sections for forming an axial bearing with complementary surface sections of the hydraulic pump  100 . On the other hand, they axially close the high pressure pump chambers  101  and the low pressure pump chambers  102  of the hydraulic pump  100 . Apart from that, the second hub lid allows for the camshaft of the combustion engine to be coupled to the hub  50 . The second hub lid  53  comprises a coupler  56  configured to provide a torque-proof connection with the camshaft wherein the coupler  56  and/or the camshaft extends through a central camshaft through-hole  12  defined in the base disc  11  of the drive disc  10 . 
     The hub  50  comprises two first adjusting channels  92 . The two first adjusting channels  92  are configured as grooves in a first axial surface  90  of the hub  50  each extending radially outward from a central through-hole  54  of the first hub lid to a vane  50  and each bending into a first peripheral direction to open into a first sub-chamber  31 . The hub  50  further comprises two second adjusting channels  93 . The two second adjusting channels  93  are configured as grooves in a second axial surface  91  of the hub  50  each extending radially outward from a central through-hole  55  of the second hub lid  53  to a vane  50  and each bending into a second peripheral direction to open into a second sub-chamber  32  wherein the first and second adjusting channels  92 ,  93  have straight sections  94  formed in the first and second hub lids  52 ,  53 , respectively. In other words, the first and second sub-chambers  31 ,  32  of the apparatus  1  are fluidly connected to the hydraulic pump  100  via the central through-hole  54 ,  55  in the first and second hub lids  52 ,  53  and via the first and second adjusting channels  92 ,  93  configured in the first and second hub lids  52 ,  53  as well as in the axial surfaces  90 ,  91  of the vanes  50 , respectively. 
     The apparatus  1  for controlling the camshaft timing adjustment further comprises a valve assembly  120  according to a preferred embodiment of the invention shown in  FIGS. 12 to 16  which is arranged within the hydraulic pump  100  and, hence, within the hub  50 . The valve assembly  120  is configured to establish fluid connections between the high pressure pump chambers  101  and the low pressure pump chambers  102  of the hydraulic pump  100  on the one hand and the first and second sub-chambers  31 ,  32  of the camshaft timing apparatus  1  on the other hand. The valve assembly  120  comprises a valve body  135  and a valve actuator  140 . 
     The valve body  135  is integrally comprised by the separating arms  112  of the rotor body  110 . In other words, the rotor body  110  has a double function. On the one hand, the rotor body  110  allows for pumping the hydraulic fluid from the low pressure pump chambers  102  to the high pressure pump chambers  101  of the hydraulic pump  100 . On the other hand, the rotor body  110  is an essential component of the valve assembly  120 . 
     The valve body  135  has a central cylindrical actuating through-hole  132  extending axially through the valve body  135  defining an axial direction  136  parallel to the common rotational axis  2 . Further, the valve body  135  comprises two first internal valve chambers  121  and two second internal valve chambers  123 . The central actuating through-hole  132  is fluidly connected to the first internal valve chambers  121 , the second internal valve chambers  123  and the radial channel sections  131  of the first and second annular channels  128 ,  129 . 
     The first and second internal valve chambers  121 ,  123  are juxtaposed in the axial direction  136  and arranged in a first pair  125  and a second pair  126  each comprising a first internal valve chamber  121  and a second internal valve chamber  123 . The first and second valve chambers  121 ,  123  of a pair  125 ,  126  are separated by a separation wall  127 , wherein the first and second pairs  125 ,  126  are juxtaposed in an axial direction and wherein the axial sequence of the first and second internal valve chambers  121 ,  123  is different between the pairs  125 ,  126 . This pairwise configuration of the first and second internal valve chambers  121 ,  123  corresponds to the configuration of the first and second adjusting channels  92 ,  93  of the hub  50 . 
     The valve body  135  comprises a first annular channel  128  associated to the first pair  125  and a second annular channel  129  associated to the second pair  126  each annular channel  128 ,  129  surrounding the corresponding first or second pair  125 ,  126  of internal valve chambers  121 ,  123 . Each annular channel  128 ,  129  has two axial channel sections  130  being disposed spaced apart in the separating arms  112 , and two radial channel sections  131 . The radial channel sections  131  connect corresponding axial ends of the axial channel sections  130  wherein each outer axial channel section  130  is configured as a groove extending in the corresponding axial surface  116  of the valve body  135 . 
     The grooves form a first control port  133  and a second control port  134  of the valve assembly  120 . The first and second control ports  133 ,  134  are arranged on axially opposite sites of the valve body  135  and are connected to each other by the central actuating through-hole  132 . 
     Each first internal valve chamber  121  has two elongate sections being arranged collinear and extending radially. The first internal valve chamber  121  has an associated high pressure channel  122  which opens into an end region of the elongate section and fluidly connects the first internal valve chamber  121  with a high pressure pump chamber  101  of the hydraulic pump  100 . Accordingly, each second internal valve chamber  123  has two elongate sections being arranged collinear and extending radially. The second internal valve chamber  123  has an associated low pressure channel  124  which opens into an end region of the elongate section and fluidly connects the second internal valve chamber  123  with a low pressure pump chamber  102  of the hydraulic pump  100 . The elongate sections of the first internal valve chambers  121  and the second internal valve chambers  123  extend parallel, and the high pressure channels  122  and the low pressure channels  124  open from opposite sides into the first and second internal valve chambers  121 ,  123 , respectively. Each of the high pressure channels  122  and low pressure channels  124  is configured as a through-hole extending from the associated internal first or second valve chamber  121 ,  123  to the respective high or low pressure pump chamber  101 ,  102  of the hydraulic pump  100 . 
     The pressure of the hydraulic fluid in the internal valve chambers  121 ,  123 , thus, is identical to the connected high pressure pump chambers  101  or low pressure pump chambers  102 , respectively. Therefore, the first internal valve chambers  121  each represent a high pressure port of the valve assembly  120  and the second internal valve chambers  123  each represent a low pressure port of the valve assembly  120 . The first and second annular channels  128 ,  129  are, via the central through-holes  54 ,  55  of the first and second hub lids  52 ,  53 , in a permanent fluid connection with the first and second adjusting channels  92 ,  93  and, indirectly, with the first and second sub-chambers  31 ,  32 , respectively. Thus, the first control port  133  is fluidly connected to the first sub-chambers  31  and the second control port  134  is fluidly connected to the second sub-chambers  32 . 
     The valve actuator  140  comprises a pin-like valve needle having an operating section  144  and an actuating section  141  wherein the actuating section  141  is arranged central and axially displaceable in the actuating through-hole  132  of the valve body  135  and wherein the operating section  144  extends through the central through-hole  54  of the first hub lid  52  and a central torque transmitting through-hole  23  of the casing lid  22  and has a head  145  at its outer free end. The valve actuator  140  may be axially coupled to a valve control unit via the head  145 . Thereby, the head  145  provides axial and radial bearing surface sections for allowing the valve actuator  140  to rotate at a different angular speed than an interface of the valve control unit providing complementary surface sections. 
     The actuating section  141  is configured to open and close the first and second internal valve chambers  121 ,  123  as well as the angular channels  128 ,  129  at different axial positions of the valve actuator  140 . The actuating section  141  comprises a plurality of annular protrusions  142  being juxtaposed in the axial direction  136  and defining axial clearances  143  between each other. The annular protrusions  142  are arranged and configured to selectively and exclusively open fluid connections between the first and second internal valve chambers  121 ,  123  and the first and second annular channels  128 ,  129 . Accordingly, the axial length and the radial width of the annular protrusions  142  as well as the axial length of the clearances  143  correspond to the axial configuration of the first and second pairs  125 ,  126  with the first and second internal valve chambers  121 ,  123  therein, of the first and second annular channels  128 ,  129  and the axial distances between these elements. 
     The valve assembly  120 , thus, works as a three-state switching valve shown schematically in  FIG. 13 . The valve assembly  120  is connected to the hydraulic pump  100  and a hydraulic motor formed by the drive disc  10 , the adjusting chambers  30 , the hub  50 , and the vanes  57 . The hydraulic motor is driven by the hydraulic pump  100  by means of the valve assembly  120 . 
     The valve assembly  120  has a first state for enabling a flow of the hydraulic fluid from the high pressure ports, i.e. the first internal valve chambers  121 , to the first control port  133  and from the second control port  134  to the low pressure ports, i.e. the second internal valve chambers  123 . In the first state the high pressure pump chambers  101  are fluidly connected to the first sub-chambers  31  as well as the low pressure pump chambers  102  are fluidly connected to the second sub-chambers  32 , respectively. In the first state, the valve actuator  140  is in a first axial position, which may be referred to as a forward position, providing a fluid communication between the high pressure pump chambers  101  and the first sub-chambers  31  as well as between the low pressure pump chambers  102  and the second sub-chambers  32 , see  FIG. 14 . In the first axial position of the valve actuator  140  fluid connections between the first internal valve chamber  121  of the first pair  125  and the first annular channel  128  as well as the second internal valve chamber  123  of the second pair  126  and the second annular channel  129  are opened, respectively. 
     The valve assembly  120  has a second state for enabling a flow of the hydraulic fluid from the high pressure ports, i.e. the first internal valve chambers  121 , to the second control port  134  and from the second control port  133  to the low pressure ports, i.e. the second internal valve chambers  123 . In the second state the high pressure pump chambers  101  are fluidly connected to the second sub-chamber  32  as well as the low pressure pump chambers  102  are fluidly connected to the first sub-chambers  31 , respectively. In the second state, the valve actuator  140  is in a second axial position different from the first axial position, which may be referred to as a backward position, providing a fluid communication between the high pressure pump chambers  101  and the second sub-chambers  32  as well as between the low pressure pump chambers  102  and the first sub-chambers  31 , see  FIG. 15 . In the second position of the valve actuator  140  fluid connections between the first internal valve chamber  121  of the second pair  126  and the second annular channel  129  as well as the second internal valve chamber  123  of the first pair  125  and the first annular channel  128  are opened, respectively. 
     The valve assembly  120  has a third state for enabling a flow of the hydraulic fluid from the high pressure ports, i.e. the first internal valve chambers  121 , to the low pressure ports, i.e. the second internal valve chambers  123 , and for closing the first control port  133  and the second control port  134 . In this state the high pressure pump chambers  101  are fluidly connected to the low pressure pump chambers  102  while the first sub-chamber  31  and the second sub-chamber  32  are separated from the high pressure pump chambers  101  and the low pressure pump chambers  102 . In the third state, the valve actuator  140  is in a third axial position different from both the first and second axial positions, which may be referred to as a neutral position, providing a short circuit fluid connection between the high pressure pump chambers  101  and the low pressure pump chambers  102  and closing the first sub-chambers  31  and the second sub-chambers  32 , see  FIG. 16 . 
     By selecting one of the first, second and third positions of the valve actuator  140 , the hydraulic fluid is either pumped from the second sub-chamber  32  to the first sub-chamber  31  to swivel the hub  50  relative to the drive disc  10  in a forward direction or pumped from the first sub-chamber  31  to the second sub-chamber  32  to swivel the hub  50  relative to the drive disc  10  in a backward direction or not pumped between the first and second sub-chambers  31 ,  32  to not swivel the hub  50  relative to the drive disc  10 . 
     The apparatus  1  further comprises a torque transmission  60  which is shown in  FIG. 17 . The torque transmission  60  is configured as a cylindrical bolt being torque-proof connected to the rotor  105  for establishing a relative rotation between the rotor  105  and the stator  104 . Thus, by securing the torque transmission  60  to a static part, i.e. a non-rotating part of the combustion engine, the hydraulic pump  100  is exclusively and immediately driven by a rotation of the hub  50  or the drive disc  10  relative to the torque transmission  60 . 
     The torque transmission  60  extends through the torque transmission through-hole  23  of the casing lid  22  and the central through-hole  54  of the first hub lid  52 . The torque transmission  60  has a coupler  62 . The coupler  62  is configured as a hexagonal head and disposed at an outer end. The torque transmission  60  has a connector  61  disposed at an opposite inner end. The connector  61  are configured to establish the torque-proof connection between the torque transmission  60  and the rotor body  110 . 
     The torque transmission  60  defines a central cylindrical operating through-hole  63 . The operating through-hole  63  extends axially and has a diameter which, at the same time, rotationally supports the operating section  144  of the valve actuator  140  and seals the casing  20  of the drive disc  10  against loss of the hydraulic fluid. The operating through-hole  63  is penetrated by the operating section  144  of the valve actuator  140 . 
     The connector  61  is configured as two pin-like protrusions being disposed eccentrically and extending axially from the inner free end of the torque transmission  60 . The pin-like protrusions are disposed on opposite sides of the operating through-hole  63 . The pin-like protrusions engage with complementary recesses  117  formed in an axial surface of the rotor body  110  and are thus an example of a torque-transmitting coupling between the torque transmission  60  and the rotor body  110 . 
     After assembly, the apparatus  1  is preferably completely filled with a hydraulic fluid. The drive disc  10  is may be connected to the crankshaft of the combustion engine. The hub  50  may be coupled to the camshaft of the combustion engine. The torque transmission  60  may be coupled to a static part of the combustion engine. The valve actuator  140  may be coupled with a valve control unit. 
     During operation, the crankshaft rotationally drives the drive disc  10  together with the enclosed hub  50 . Assuming no fluid flow between the sub-chambers  31 ,  32  the drive disc  10  drives the hub  50  and thus the camshaft. The rotation of the internal gear  106  which rotates with the hub  50  relative to the rotor body  110  (which does not rotate due to the torque transmission  60 ) drives the hydraulic pump  100 . The hydraulic pump  100  generates a pressure gradient between its pump chambers  101 ,  102  which, consequently, act as high pressure pump chambers  101  and low pressure chambers  102 . The valve control unit may control the valve assembly  120  by axially displacing the valve actuator  140  on demand into one of three axial positions. Depending on the axial position of the valve actuator  140  the hydraulic fluid is pumped or not pumped between the first and second sub-chambers  31 ,  32 . Correspondingly, the hub  50  is swivelled forth or back or not swivelled relative to the disc drive  10  in order to adjust or maintain a required angular relation between the drive disc  10  and the hub  50  or the crankshaft and the camshaft of the combustion engine, respectively. 
     The apparatus  1 , hence, is very compact due to integrating the valve assembly  120  into the hydraulic pump  100  and, at the same time, integrating the hydraulic pump  100  into the hub  50 . Apart from that, the hydraulic pump  100  can immediately be driven by the camshaft without imposing any immediate load on the crankshaft. 
     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.