Abstract:
A cylinder valve operating system for an internal combustion engine includes a camshaft driving a number of intake and exhaust valve operators which may be selectively disabled through the operation of a valving system including a hydraulic phase shifter integrated with the camshaft and connected between a source of high pressure oil and at least the intake valve operators. The hydraulic phase shifter allows one group of valves, such as the exhaust valves, to be disabled before the other group of valves, typically the intake valves.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    None. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a reciprocating internal combustion engine having poppet valves which are driven by a camshaft. The valves may be disabled selectively, so as to effectively change the displacement of the engine. 
         [0004]    2. Disclosure Information 
         [0005]    Dual displacement engines characterized by the capability to deactivate the intake and exhaust valves for particular cylinders, so as to increase fuel economy, are known in the art. One method for deactivating valves involves a hydraulic control of the valve actuation systems. Unfortunately, hydraulic control is rendered more expensive because of the need to provide separate control circuits, including control valves, for both the intake and exhaust valves. In other words, electronic control valves must be provided to meter or restrict the flow of oil to the valve operators for both intake and exhaust valves. In a V-type engine, this commonly means that four electronic control valves must be employed to deactivate various cylinders of the engine. 
         [0006]    It would be desirable to provide a deactivation system requiring only a single valve for each bank of cylinders, while preserving the phasing necessary to properly deactivate and reactivate the cylinders. In general, phasing is best accomplished by deactivating the exhaust valve first for any particular cylinder, followed by deactivation of the intake valve for the same cylinder. Deactivation of the intake and exhaust valves in this sequence will trap a burnt charge in the engine&#39;s cylinder, preventing excess vacuum in the cylinder, which could pull in crankcase gases. This phased deactivation of the exhaust and intake valves will avoid a puff of unburned hydrocarbon when the cylinders are reactivated. Heretofore, this phasing aspect has, as noted above, required multiple control valves. The present invention avoids the need for multiple deactivation control valves for any particular bank of cylinders in an engine. 
       SUMMARY OF THE INVENTION 
       [0007]    A cylinder valve operating system for an internal combustion engine includes a camshaft having a number of lobes and a corresponding grouping of hydraulically controllable intake valve operators and hydraulically controllable exhaust valve operators. All of the various operators are driven by the camshaft lobes. A number of intake valves are actuated by the intake valve operators, and a number of exhaust valves are actuated by the exhaust valve operators. A source of high pressure oil is valved to the intake valve operators and to the exhaust valve operators. The valving system includes a hydraulic phase shifter integrated with the camshaft and connected between the source of high pressure oil and the intake valve operators and exhaust valve operators, so as to phase the hydraulic control of the intake valve operators with respect to the exhaust valve operators. This delays deactivation of certain intake valves until the exhaust valves for each respective cylinder have been deactivated. 
         [0008]    According to another aspect of the present invention, the valving system for controlling the flow of high pressure oil to the intake and exhaust valve operators further includes a supply valve for coupling the source of high pressure oil to the hydraulic phase shifter. 
         [0009]    According to another aspect of the present invention, a hydraulic phase shifter includes a valve body having a central bore equipped with a supply port for receiving oil from the high pressure source, and a number of outlet ports, with the first outlet port connected with the intake valve operators and a second outlet port connected with the exhaust valve operators. A metering surface is formed on the journal of the camshaft, such that the metering surface extends within the central bore of the valve body. The metering surface includes a generally cylindrical surface having a plurality of metering grooves for connecting the supply port with the outlet ports in a phased relationship. 
         [0010]    The camshaft&#39;s metering grooves, according to another aspect of the present invention, preferably include a continuous circumferential groove for connecting the supply port with an outlet port operatively connected with at least one exhaust valve operator, and a discontinuous, semi-circumferential groove adjoining the continuous groove, for intermittently connecting the supply port with at least one intake valve operator. According to another aspect of the present invention, the valve body may be configured as a camshaft mounting tower integrated with a cylinder head of the engine. 
         [0011]    In order to promote smoother operation of the present system, the valving system may further include an intermittent bypass for routing oil directly from the high pressure source to at least one of the intake valve operators and exhaust valve operators, without passing through the hydraulic phase shifter. The system may also include a hydraulic accumulator interposed between the hydraulic phase shifter and at least one of the intake valve operators and exhaust valve operators. 
         [0012]    The present system provides hydraulic control to selectively disable the exhaust and intake valves actuated by the system&#39;s intake and exhaust valve operators. The hydraulic phase shifter cooperates with the intake valve operators and the exhaust valve operators to disable at least one intake valve and at least one exhaust valve, with the exhaust valve being disabled before the intake valve on a given cylinder, so as to trap burned exhaust gas within at least one cylinder of the engine. 
         [0013]    According to another aspect of the present invention, the intake valve operators and exhaust valve operators may each include a camshaft follower, a valve actuating finger, and a hydraulically lockable pin slidably located between the camshaft follower and the valve actuating finger, with the hydraulically lockable pin being responsive to oil pressure within a rocker shaft or other oil passage which is connected with the hydraulic phase shifter integrated with the camshaft. 
         [0014]    It is an advantage of a cylinder valve operating system according to the present invention that cylinder deactivation may be accomplished with a minimum amount of hardware and, more specifically, with a single solenoid operated valve per cylinder bank. 
         [0015]    It is yet another advantage of a system according to the present invention that cylinder deactivation may be phased with only a single electronic switching valve in the system because the present hydraulic phase shifter utilizes the motion of the camshaft to achieve intake-to-exhaust phase shifting without the need for intervening electronic devices. 
         [0016]    Other features and advantages of the present invention will become apparent to the reader of this specification. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a schematic representation of a portion of a cylinder valve operating system according to an aspect of the present invention. 
           [0018]      FIG. 2  is a sectional view of an engine having a cylinder valve operating system according to the present invention. 
           [0019]      FIG. 3  shows a valve operator according to an aspect of the present invention. 
           [0020]      FIGS. 4A and 4B  illustrate a bypass valve according to an aspect of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0021]    As shown in  FIG. 2 , engine  10  has a cylinder head,  12 , which houses a camshaft,  14 .  FIG. 1  shows camshaft  14  as being driven by sprocket  16 . As shown in  FIGS. 1 and 2 , camshaft  14  has a number of cam lobes,  18 , which provide force impulses for opening intake valves  30  and exhaust valves  34 . Intake valves  30  are driven by intake valve operators  22 , which are mounted upon intake rocker shaft  24 . Exhaust valves  34  are operated by exhaust valve operators  26 , which are mounted upon exhaust valve rocker shaft  28 . Intake valve operators  22  include intake valve contactors  35 , and exhaust valve operators  26  include exhaust valve contactors  32 . 
         [0022]    Engine  10 , being a reciprocating internal combustion engine, further includes piston  36  mounted upon connecting rod  40 , as well as combustion chamber  44 . Valves  30  and  34 , being conventional poppet valves, effectively deactivate the engine&#39;s power cylinder when the valves  30  and  34  are maintained in a steady-state closed position. During deactivation it is desirable to trap a charge of burnt exhaust gasses within combustion chamber  44 , and the system shown schematically in  FIG. 1  accomplishes this. 
         [0023]    Moving specifically to  FIG. 1 , camshaft  14  is shown as having a metering surface formed as a generally cylindrical journal,  20 , which has a continuous metering groove,  13  which circumscribes journal  20 , as well as a discontinuous metering groove  15 , which has at least one land  15   a , which establishes the discontinuity of groove  15 . Journal  20  extends within a central bore,  55 , formed within valve body  52 . Those skilled in the art will appreciate in view of this disclosure that valve body  52  may be configured as ether a stand-alone valve block, or as the illustrated camshaft mounting tower combining the function of both a valve block and a camshaft saddle. In either event, metering groove  13  connects supply port  62 , which is downstream from supply valve  48 , to outlet port  54 , which is in turn connected with exhaust valve rocker shaft  28  shown in  FIGS. 2 and 3 . Rocker shaft  28  has an axial passage,  29 , which conducts high pressure oil for deactivating exhaust valve operators  26 . 
         [0024]    When high pressure oil from oil pump  42  moves through valve  48  and into supply port  62 , pressure communicated through continuous metering groove  13  builds immediately at outlet port  54 , thereby deactivating exhaust valve  34 , as described below in connection with  FIG. 3 . However, because of land  15   a , which is part of discontinuous groove  15 , the pressure signal from supply port  62  is communicated to outlet port  58 , which is connected with intake rocker shaft  24 , only after land  15   a  moves past outlet port  58 . As a result, the combination of camshaft journal  20  with valve body  52  functions effectively as a hydraulic phase shifter integrated with camshaft  14  so as to phase, or delay, the hydraulic signal to intake valve operators  22 , thereby delaying their deactivation, as compared with exhaust valve operators  26 . This traps a charge of burnt gases within combustion chamber  44  of engine  10 . Those skilled in the art will appreciate in view of this disclosure that pump  42  could be configured either as a lubricating oil pump for engine  10 , or as a dedicated hydraulic pump, or yet another type of pump suggested by this disclosure. 
         [0025]    In  FIG. 3 , exhaust valve operator  26  is shown as having an oil passage,  70 , which extends within camshaft follower  78 , and which communicates with port  66  in rocker shaft  28 . Piston  74  and latching pin  76  selectively lock follower  78  to exhaust valve contacting finger  32 , which causes finger  32  to move in response to the motion of follower  78 . Piston  74  is acted upon by oil pressure within oil passages  29  and  70 . High oil pressure within passage  70  forces piston  74  from the at-rest position of  FIG. 3 , against the force of spring  80 , which acts upon normally locked latching pin  76 . When normally locked latching pin  76  is fully displaced by high pressure oil acting upon piston  74 , latching pin  76  stops at a position where follower  78  is no longer locked to exhaust valve contacting finger  32 , and exhaust valve  34  is therefore disabled. While operator  26  is in this disabled state, camshaft follower  78  merely rocks according to the movement of one of cam lobes  18 , while exhaust valve  34  and finger  32  remain stationary in the closed position. Those skilled in the art will appreciate in view of this disclosure that oil passage  70  and piston  74  could be situated within finger  32 , with latching pin  76  and piston  74  being housed within camshaft follower  78 . 
         [0026]    Because the pressure signal within outlet port  58  tends to pulsate as a result of the intermittent interruption of the supply of oil occasioned by the action of land  15   a  of discontinuous metering groove  15 , in a preferred embodiment, hydraulic accumulator  46  ( FIG. 1 ) may be inserted in the passage between outlet port  58  and intake valve operators  22 . Additionally, or alternatively, bypass valve  98 , shown in  FIGS. 4A and 4B , may be provided. In  FIG. 4A , bypass valve  98  is shown in a closed position, such that pressure from outlet port  58  passes freely to intake valve operator supply passage  100 . Note that in  FIG. 4A , the flow of oil from port  62  is blocked by the position of spool  108 . Once, however, pressure is applied by means of control valve  48 , and pressure is allowed to build within intake operator supply passage  100 , valve spool  108  will be pushed to the open position, as shown in  FIG. 4B . When valve  98  is in the position as shown in  FIG. 4B , high pressure hydraulic fluid, which is often engine oil, flows through control port  116  from port  62  and to intake valve operators  22 , so that the effect of the pulsation which would otherwise be caused by the hydraulic phase shifter integrated with camshaft  14  will be mitigated. 
         [0027]    Those skilled in the art will appreciate in view of this disclosure that valve operator passage  100 , which is operatively connected with intake valve operators  22 , may be incorporated, for example, as passage  25  within hollow rocker shaft  24 , in the event that the illustrated shaft-mounted rocker arms are employed. Alternatively, passages may be cored or drilled within a cylinder head casting if pedestal-mounted rockers are used. 
         [0028]    According to another aspect of the present invention, both the intake valve operator and the exhaust valve operator of a first cylinder may be controlled simultaneously by connecting one of outlet ports  54  and  58  to both operators of the first cylinder. If the intake and exhaust valve operators of a second cylinder are connected with the other of outlet ports  54  and  58 , the result will be that deactivation and reactivation of both the intake valve and the exhaust valve of the second cylinder will be phased with respect to the first cylinder. In essence, the present system is useful for phasing the deactivation and reactivation of a first group of valve operators, associated with a first cylinder, with respect to a second group of valve operators associated with a second cylinder. 
         [0029]    Although the present invention has been described in connection with particular embodiments thereof, it is to be understood that various modifications, alterations, and adaptations may be made by those skilled in the art without departing from the spirit and scope of the invention set forth in the following claims.