Abstract:
A compact engine assembly employing an auxiliary shaft that drives engine accessories that are disposed on opposite sides of its rotational axis by separate flexible transmitters so as to reduce eccentric loading. Also, the drive pulleys for the accessories are disposed inwardly from one end of the engine so as to maintain a relatively short overall length as well as permitting a narrow width for the engine. An engine oil pump positioned within an engine end wall is also driven from the auxiliary shaft.

Description:
BACKGROUND OF INVENTION  
         [0001]    This invention relates to an auxiliary equipment arrangement in an engine and more particularly to an improved drive arrangement for driving engine auxiliaries from an intermediate shaft of the engine.  
           [0002]    There has been proposed a type of engine that has an intermediate shaft which is driven off a location between the ends of the main crankshaft and which itself drives a plurality of accessories. Such an arrangement is shown in Japanese Published Application 2000-205066, published Jul. 25, 2000.  
           [0003]    With this arrangement, a plurality of accessories is disposed around a pulley at one end of the intermediate shaft of the engine. These accessories all are driven by a single serpentine flexible transmitter. As a result of this arrangement, the bearings on the intermediate shaft are loaded primarily on only one side of the rotational axis of the shaft causing high loadings on its bearings, particularly those adjacent the driving pulley. In addition, it is necessary to place idlers or further accessories close together on the opposite side of the engine in order to maintain a substantial contact of the flexible transmitter with its driving pulley. This results in not only high bearing loads, but also in increased weight and size of the engine in order to accommodate their loads. In addition, this driving arrangement is disposed outwardly of one end of the engine and thus, adds to the overall length of the engine.  
           [0004]    It is, therefore, a principal object to this invention to provide an improved accessory drive for driving engine accessories from an intermediate shaft of the engine.  
           [0005]    In addition to those external accessories for the engine, there are also a number of internal accessories that are driven from the engine. An examples of such internal accessories is the oil pump, which collects oil from the oil tank or crankcase and circulates it to the various components of the engine for their lubrication. Frequently, this oil pump is located in the crankcase and is driven from the engine crankshaft. One problem with this type of location is that the engine oil pump is very difficult to obtain for servicing and frequently even the engine must be removed from the chassis of the vehicle to service the oil pump.  
           [0006]    It is, therefore, a further object of this invention to provide an improved oil pump drive for an engine wherein the engine oil pump can be easily removed for servicing.  
           [0007]    It is a further object to this invention to provide an improved arrangement for driving the oil pump directly from an end of the intermediate shaft.  
         SUMMARY OF INVENTION  
         [0008]    This invention is adapted to be embodied in an internal combustion engine having a cylinder block with a plurality of aligned cylinder bores, each of which contains a piston for driving a crankshaft journalled in a crankcase formed at the lower end of the cylinder block. An auxiliary shaft is journalled for rotation about an auxiliary shaft axis at one side of the cylinder block and is driven by the crankshaft. A pair of pulleys is fixed at one end of the auxiliary shaft. A pair of engine accessories is mounted at the one side of the cylinder block on diametrically spaced sides of the auxiliary shaft axis. First and second flexible transmitters drive the pair of engine accessories from respective ones of the pair of pulleys.  
           [0009]    In accordance with another feature of the invention, the crankshaft is journalled by at least two bearings positioned in opposite end walls of the engine and at least one of the auxiliary shaft pulleys is disposed inwardly of at least one of the engine end walls so as to reduce the overall length of the engine.  
           [0010]    Another feature of the invention is adapted to be embodied in an internal combustion engine having a cylinder block with a plurality of aligned cylinder bores each containing a piston driving a crankshaft journalled in a crankcase formed at a lower end of the cylinder block. An auxiliary shaft is journalled for rotation about an auxiliary shaft axis at one side of the cylinder block and is driven by the crankshaft. An engine accessory is driven by the auxiliary shaft externally of a body of the engine. An oil pump is driven from the end of the auxiliary shaft adjacent the external engine accessory. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0011]    [0011]FIG. 1 is a front elevational view of an internal combustion engine constructed in accordance with an embodiment of the invention.  
         [0012]    [0012]FIG. 2 is an enlarged cross sectional view taken along the line  2 - 2  of FIG. 1. 
     
    
     DETAILED DESCRIPTION  
       [0013]    Referring now in detail to the drawings, an internal combustion engine constructed in accordance with an embodiment of the invention is identified generally by the reference numeral  11 . The engine  11 , because of its compact nature, is particularly adapted for use in transverse positioning within the engine compartment either at the front or rear of an automotive vehicle. Of course, other utilizations for the engine are possible, such as in motorcycles, as are other engine placements in an associated engine compartment.  
         [0014]    The engine  11  is comprised of a cylinder block, indicated generally by the reference numeral  12  and which has a number of cylinder bores which do not appear, but which have axes indicated by the line  13 . In the specific embodiment illustrated, the engine may be of the five cylinder, in-line type but, of course, any suitable number of cylinders may be employed.  
         [0015]    As may be seen in FIG. 1, the cylinder block  12  is disposed so that the cylinder bore axes  13  lie in a common plane that is disposed at an acute angle to a vertical plane indicated at V in FIG. 1. In other words, the cylinder block  12  is canted slightly to the right as shown by the directional arrows in this figure.  
         [0016]    A cylinder head assembly  14  of any known type is fixed to the cylinder block  12  and is provided with a valving system comprised of intake and exhaust valves that control the flow of air to the combustion chambers and the discharge of exhaust gases there from. Since any type of valve mechanism may be employed as well as the associated induction and exhaust systems, this structure is not illustrated, nor are the pistons which reciprocate in the cylinder bores.  
         [0017]    Beneath the cylinder block  12  there is provided a crankcase assembly, indicated generally by the reference numeral  15  which is comprised of a crankcase member  16  which is affixed to the cylinder block  12  and that journals the main bearing portions  17  of a crankshaft, indicated generally by the reference numeral  18 . These main bearings are shown in FIG. 2 and are indicated by the reference numeral  19 .  
         [0018]    The rotational axis of the crankshaft is indicated at CR in the drawings and it will be seen that this coincides with the point where the plane containing the cylinder bore axes  13  intersect the vertical plane V.  
         [0019]    Crank journals  21  are formed by pairs of throws  22  of the crankshaft  19  and journal the big ends of connecting rods, the small ends of which are connected to the pistons in the individual cylinder bores for driving the crankshaft  18  in a well known manner. These throws have rotational axes  23 , one of which is identified in FIG. 2.  
         [0020]    The crankcase assembly  15  is completed by an oil pan  24  that is affixed to the lower end of the crankcase member  16  and which defines an oil reservoir and encloses the crankcase cavity  25  in which the crankshaft  18  is journalled.  
         [0021]    The left side of the cylinder block  12  and crankcase member  16  are formed with respective extensions  26  and  27  that form surfaces that receive bearings  28  for journaling bearing portions of an intermediate shaft, indicated generally by the reference numeral  29 . These intermediate shaft bearing portions are indicated by the reference numeral  31 . Thus the intermediate shaft  29  is journaled for rotation about an axis that is parallel to the rotational axis CR of the crankshaft  18 . This intermediate shaft rotational axis is indicated by the reference character IR.  
         [0022]    One of the throws  22  of the crankshaft  18  is formed with in integral gear that meshes with a gear formed on the intermediate shaft, these gears each being indicated by the reference numeral  32 . Thus, the intermediate shaft  29  is driven at the same rotational speed as the crankshaft  18  but in an opposite direction. If desired, one of more balance masses  33  may be formed on the intermediate shaft  29  between adjacent pairs of the bearing portions  31  for assisting in engine balancing.  
         [0023]    Also, the cylinder block and crankcase member portions  26  and  27  define at one end portion thereof a cavity  34  in which a pumping member (not shown) of an oil pump is positioned. This pumping member is driven by an intermediate shaft portion  35  and receives lubricant from the crankcase  25  and circulates it to the engine through suitable passages formed in the crankcase member  16  and the cylinder block  12 . This includes passages for lubricating the bearings  19  and  28 . The oil pump may be of any known type such as a gerotor pump or the like and the cavity  34  is closed by a suitable cover plate. Thus, this provides a compact construction and an easily serviced oil pump.  
         [0024]    It should be noted that the portions  26  and  27  of the cylinder block and crankcase member are recessed from a front wall  36  of the engine which forms a flange  37  in which the front main bearing  19  for the crankcase bearing portion  17  is positioned. This defines a recess, indicated generally by the reference numeral  38  in which an accessory drive mechanism, now to be described, is positioned.  
         [0025]    A pair of pulleys comprised of a smaller diameter, inner pulley  39  and a larger diameter, outer pulley  41  are fixed to this end of the intermediate shaft  29 . These pulleys  39  and  41  are located substantially within the recess  38  and substantially rearwardly of the front engine wall  39 .  
         [0026]    A first flexible transmitter  42  is engaged with the smaller diameter pulley  39  and drives a further pulley  43  of an engine accessory such as an air conditioning compressor, indicated generally by the reference numeral  39 . This engine accessory  39  is disposed on the diametrically lower side of the intermediate shaft rotational axis IR. The axis of rotation of the air conditioning compressor is indicated, as CR and it will be seen that this axis is offset toward the vertical plane V from the rotational axis IR of the intermediate shaft. This permits the air conditioning compressor  39  to be tucked closely within a recess formed at the lower side of the oil pan  24 , as seen in FIG. 1, and permits a relatively narrow width W for the engine in the fore/aft direction of the associated vehicle.  
         [0027]    A further engine accessory, such as an alternator  44 , is disposed above the rotational axis IR of the intermediate shaft and is provided with a driving pulley  45  that is driven by a drive belt  46  that is trained around it and around the larger pulley  41  of the intermediate shaft  29 . The rotational axis AR of the alternator  44  lies on a plane AP that passes through the axes AR, IR and CR and is disposed adjacent to the cylinder block but further from the plane  13  containing the cylinder bore axes than the air conditioning compressor  39 . As a result, the construction can be kept quite compact.  
         [0028]    Because the pulleys  39  and  41  are spaced primarily inwardly from the engine end wall  36 , the overall length of the engine L may be kept quite compact as well as the narrow width W. Also, since the two pulleys are driven from the intermediate shaft  29  on opposite sides of its rotational axis IR, the bearing loads are more uniform and the bearings  28  may be made smaller than with the prior art type of construction.  
         [0029]    Thus, from the foregoing description it should be readily apparent that the described engine construction is not only compact but also minimizes loadings on the engine and the accessory drives. Of course, the foregoing description is that of a preferred embodiment of the invention and various changes and modifications may be made without departing from the spirit and scope of the invention, as defined by the appended claims.