US2151614A - Swash plate type engine - Google Patents

Description

March 21, 1939. C. G. NEYATT ET AL. 2,151,614'

SWASH PLATE TYPE ENGINE Filed Sept. 17, 1937 3 Sheets-Sheet 1 IIVENTORS 6. BY W.

a 1' "M ATTYS.

HEARE'R 1 March 21, 1939.

c. e. NEVATT' ET AL SWASH PLATE TYPE ENGINE Filed Sept. 17, 1957 3 Sheets-Sheet 2 ve'n arm:

March 21, 1939. c. G. NEVATT ET AL swAsH PLATE: TYPE ENGINE Fil ed Sept. 17, 1937 s Sheets-Sheet 3 5 Wg, 21w, After-way:

Patented Mar. 21, 1939 UNITED STATES PATENT OFFICE SWASH PLATE TYPE ENGINE Christopher George Nevatt and Francis West ish company Application September 17,

1937, Serial No. 164,416

In Great Britain September 24, 1936 .9 Claims.

This invention isfor improvements in or relating to a swash-plate engine of the kind wherein the engine-shaft is provided with an inclined crank pin or the like which is rotatable in the swash-member and wherein means are provided ,for so constraining the movement of the swashmember that all points in a plane at right-angles to the inclined crank-pin and atequal distances therefrom traverse difierent paths of the same shape and wherein the connecting-rods of the engine are articulately connected to the swashmem-ber. It is already known that the correct path of movement is a specific form of lemniscate.

The present invention is based on the observation that the lemniscate path is produced by the combined movements of a point rotating about an axis parallel with the engine-shaft and at the same time moving backwards and forwards along the axis, thus producing a form of helix. The lemniscate, as Viewed along said axis, is a circle the equation of which may befound to be where y and z are co-ordinates at right-angles to one another :in a plane at right-angles to the engineshaft, and a is the angle which the inclined crank-pin makes with the engine axis. The radius of the circle is equal to R(l cos a) 2 The present invention consists in providing guide means which engage apart of the swashmember ora part connected thereto the contour .of which guide means is such that the guided member moves in .a path which, when projected on to a plane at right-angles to the engine-shaft, is a circle having the above equation. With this arrangement the constraint provided by the guide means .coupled with the movement imparted to the swash-member by the crank-pin on which it is mounted will result in the desired lemniscate form of motion.

Assuming the guided member has a radius of K, the point of contact of centre of pressure between the ;guided member and guiding surface traverses a path whch, viewed along .a line parallel with the axis of the engine shaft is a circle or a part of a circle having the equation The means for constraining the swash-member may comprise a member which is guided to .move in a direction along the engine-shaft, a universal joint between said guide member and the swash-member, a loose connection either between said guided member and a part of said joint, or between two relatively movable parts of said joint, or between a part of said joint and the swash-member, which connection is arranged to permit relative movement between the parts it connects in a direction towards and away from the engine-shaft and in a direction transverse to the axis of the shaft; preferably it also limits 5 those movements so that they lie within a cylindrical boundary which, when projected on a plane at right-angles to the engine-shaft, is a circle having the equation referred to above. In this arrangement the guided member and said connection constitute the guide means whereby a part of-the swash-member is constrained to move aroundthe cylindrical envelope. The words universal joint are intended to include both a balland-socket joint and a joint of the kind in which movement takes place about two axes at rightangles to one another, such for example, as a Hooke"s-type joint. If the latter type of joint is employed, it is arranged so that one oftheaxes lies in a plane at right-angles to the inclined crank-pin.

It is a characteristic of a swash-member of the kind first referred to above that although points equidistant from and distributed around the inclined crank-pin in a plane at right-angles to the crank-pin all move in the same lemniscate form of path, at any one moment they are traversing diiferent parts of the path. For example, while one point on the swash-member is traversing the end of a lemniscate, another point on :theswash-member 'angularly disposed from the first said point by 90 will be at the cross-over point of the lemniscate. By guiding one part of the swash-member all other parts are constrained to move in the'desired manner. If, however, a number of parts of the swash-member are guided, it is not necessary for each part to be constrained by its guide aroundthe whole lemniscate but the combined eifect of the guides must be such as to result in all the parts being constained along the whole length of their lemniscates.

It will therefore be appreciated that a number of guide means may be associated with different parts of the swash-member distributed around the crank-pin, each of which may either be arranged to constrain its part of the swash-member to move along the whole of the path of the lemniscate or along only a part thereof, in which latter case, the other guide means collectively constrain said first part to move along the remaining portion of the lemniscate.

A feature of the invention consists in that said guided member or members comprise one or other of the connecting-rods of the engine, which is or are guided to move in a straight line parallel with the engine-shaft and has associated therewith a universal joint and a connection in the manner referred to above. The provision of a connecting-rod moving in a straight line parallel with the engine-shaft is particularly useful inconnection with internal-combustion engines in which the cylinders are arranged parallel with and distributed around the engine-shaft since the ends of the cylinders adjacent the swash-member may be closed and isolated from the chamber in which the swash-member is mounted. Furthermore, better balance is obtainable when the connecting-rod is moved in a straight line than in the previous arrangements in which the whole of the connecting-rod had imparted to it a wobbling motion.

The following is a description of a number of constructions of swash-plate mechanism suitable for use in internal-combustion engines, reference being made to the accompanying drawings, in which- Figure 1 is a section in a plane containing the engine-shaft axis through those parts of the mechanism which guide the connecting-rod and connect it to the swash-member;

Figure 2 is a half-section on the line 2-2 of Figure 1 and an end elevation looking in the direction of the arrows of Figure 1;

Figure 3 is a plan view of Figure 1 in which the guide means for the connecting-rod are shown in section;

Figure 4 is a similar section to that of Figure 1 vof an alternative form of construction in which one part of a ball-and-socket joint is secured to the engine connecting-rod and in which a part .of the swash-member slidingly engages the other part of the joint;

Figure 5 is a section ;on the line Figure 4;

Figure 6 is a similar section to that of Figure 1 of an alternative construction in which one part of the universal joint is secured to the connecting-rod and the other part of which is secured .to the swash-member, and in which a sliding connection is provided between the two parts of the universal joint;

Figure 7 is a section on the line 1-1 of Figure 6; and 5 Figure 8 is a half-section on the line 8-8 of Figure 6 and a half-plan view of Figure 6.

All the constructions about to be described are applicable to an internal-combustion engine in which the cylinders are arranged parallel with and distributed around the engine-shaft. The engine-shaft is provided with an inclined crankpin which is rotatable in a swash-member. Each cylinder contains a piston having a connectingrod which is articulately connected to the swashmember.

Referring now to the construction shown in Figures 1 to 3, the connecting-rod I0 is provided with a head II which is engaged by a flange l2 on a nut-member 13. The nut is arranged to engage a screw-threaded shank M on a plug IS. The plug is externally threaded and engages an internally-threaded sleeve I6. A similar plug l1, without a central shank, is arranged to engage the other end of the sleeve. The sleeve is a good sliding fit in a hollow cylindrical guide-member 18 which is fixed to the engine casing so that ripheral wall 4 I.

its axis lies parallel with the engine-shaft. Thus the connecting-rod II! is guided to move along said axis. Any or all of said connecting-rods may be guided to move in this manner.

The swash-member I9 is circular in contour,

is mounted on the inclined crank-pin 5 of the crankshaft 6 and has secured to it a number of radially-extending arms 20 having spherical heads 2|, one arm being provided for each connecting-rod. The arm extends through a longitudinal slot 26 in the guide-member I8. The spherical head is embraced by a two-part socket member 22 which is straddled by a clamping member I having on either side thereof tubular trunnions 23. Each tubular trunnion is internally threaded to receive a clamping screw 8 and is surrounded by a hard steel cap-member 24 having a cylindrical outer surface. The trunnions with their caps are located in cylindrical recesses 25 formed in the plug members l5 and H. The diameters of the cap-members 24 and the cylindrical recesses 25 are so selected that when the trunnions traverse the peripheral wall of the recesses the axis of the trunnion describes a circle having the equations referred to above.

The above mechanism, in effect, comprises a ball-and-socket joint, one part of which is fixed to the swash-member and the other part of which is connected to the guided end of the connectingrod through a loose connection having a guidemember, viz. the plugs 15 and l! with a cylindrical recess. Since this cylindrical recess is reciprocated backwards and forwards in a straight line it has a cylindrical envelope, the projection of which on a plane at right-angles to the engineshaft is a circle having the above equation.

The torque reaction of the engine-shaft is transmitted between the cap-members 24 and the peripheral wall of the cylindrical recess but where each connecting-rod is provided with the mechanism the combined surfaces are well able to withstand the loads imparted to them. As already indicated above, however, it may not be necessary for each mechanism to be provided with a complete guiding surface so long as the combined effect of all the guiding surfaces is to effect the required lemniscate movement.

Referring now to the construction shown in Figures 4 and 5, a socket-member 21 of a balland-socket joint may be secured to the end of any or all of the connecting-rods 28. The socketmember is formed in two parts, one of which is formed integral with the connecting-rod 28 and the other of which is secured to the first part by bolts 29 (see Figure 5). These bolts pass through lugs 30 formed on either side of the socket-member, which lugs are provided with flat faces 3| which are engaged by guide-ways 32 fixed to the engine casing, so as to guide the connecting-rod in a line parallel with the engineshaft. The ball 33 of the joint is formed in two parts, one of which is provided with an internally-threaded recess which engages a threaded projection on the other part, as indicated at 34.

The ball is provided with a screw-threaded stem 35 which projects out through a slot 36 in the socket-member and is provided with a nut 31 and a washer 38 which latter engages an outer surface of the socket-member. The stem extends through a block 9 which engages the sides of the slot. Formed in the ball 33 is a diametricallyextending slot 39 having flat sides 40 and a pe- Fixed to the swash-member 42 are a number of radially-extending arms, onefor each connecting-rod, which are provided with heads 44 having =flatfaces which enga e the zflat sides :40 of the :slot and which are circular in contour, as seen in Figure 5. The arms ;43 extend through a ,slot 45 .formed in the socketmember. "Ihehead-M eontactswith the ripheral wall 4| and precesses around it. The contour .ofthe peripheralwa'llis so selected that-t-he point of contact between it and r-the head traverses a path which when projectedon a :plane at right-angles to the engine -shaft is a circle havingan equation as set out at the commencement of the specification;

In effect, the above mechanism comprises a ball-and-socket joint, one part of which is secured to the connecting-ro'd-andtheotherpart of whichis secured to-the swash-member through a connection which provides the requisite guiding means 'for effecting the desired lemniscate path. -A similar mechanism maybe associated witheachconnecting-rod but, as indicated above, a-complete elliptical-bearing surface need not be provided in each mechanism.

Referring now to theconstruction shown in Figures 6 to 8, the end of the connecting-rod ,46 is secured in a socket in a bearing-block 4;! by a bolt 48. The bearing block =41 :has flat sides-49 (see Figure 7) which slidingly engage the side wallsof a channel-shaped guide member 5.5!; -The bearing-block is provided with a cylindrical bore whichis closed at one end-by a cap-member '5! having an externally-threaded rim which engages theinternally-threaded part of said bore. A flat cover-p1ate;52 is secured ,over the open end of the channel-shaped guide-member so as to bear against the cap-member The cover-plate is secured in position by an angle-plate 53 having flanges '54 which engage recesses 55 in the side walls of the guide-member. Bolts 56 extend through the angle-plate and engage threaded holes in the bottom wall 51 of-the channel-shaped guide-way, The channel-shaped guide-wayis so disposed as to guide the connecting-rod to move in a straight 'line parallel with the engine-shaft. Located in the cylindrical 'bore of the bearingblock is a guide-block 58 having a slot formed therein, the two opposite walls 59 of which are fiat, as seen in Figure 6, and the other two opposite walls '60 are curved, as seen in Figure 7. The outer surface of the guideblock -is cylindrical and forms a good rotating fit-in the cylindrical bore of the 'bearing block.

As in the previous constructions, the swashmember is provided with a number of radiallyextending arms 6|, one for each connecting-rod. Each of the arms extends through a ;slot 62 formed in the bottom wall 51 of the channelshaped guide-member. As \will be seen from Figure 7, the end of the iradial arm .is provided with a bored boss 63. Each end of the boss is encircled by an annular cap-member 64 and a bolt 65 extends through the holes in the two annular cap-members so that they are clamped together on each side of the boss.

Two opposite sides of the annular cap-members are flat and engage the flat sides 59 of the slot in the guide-block. The other opposite sides are spherically shaped, as indicated at 66 in Figure 7. This arrangement, in effect, provides a Hookestype joint in which one pivot axis is constituted by the joint between the radial arms BI and the annular cap-members E4 and the other pivot of the joint which is at right-angles thereto is constituted by the cylindrical bearing between the bearing-block 58 and the guide-block 41. The aforesaid connection is provided between the two na tsoizthe iointandin o der that thenece sa y lernniscate movement :may result, the curve re quires to :be egg-shaped. It will be appreciated that through one cycle of movement the guideblock 58 will be oscillatingabout anaxis at rightangles to the engine-shaft and the annular capmcmbers will be precessing around the curved surface. At any one moment that part of the curved surface with which the annular capmember is in contactrshould, when projected on a :plane at ;rightang1es to :the engine-shaft, be a tel-role. Since, however, that surface is oscillating about the aforesaid axis, it will require to be egg-shaped as aforesaid.

We claim:

A'swash-plate engine comprising an enginehaft havin an inclined crank pi a swashmember mounted on said crank-pin, a number of connecting-rods for the engine pistons articulately connected to said swash-member, a guide extendingin a direction along the engine-shaft, a ,partmovable along said guide, a universal joint between said guided parts and the swash-member, a loose connection between two relatively movable parts of said joint, which loose connection comprises a circular part, Within an encircling guide-surface, of such shape-that the path of movement of the point of contact between those parts as viewed along :a line parallel with the axis ;of the engine, ;is a ci rc le having the equation 2. ,A swash-plate engine comprising, an engineshaft having an inclinedfcrank-pin, a swashmember mounted on said crank-pin, a number of connecting-rods for theengine pistons articulately connected to said swash-member, a guide extending in a direction along the engine-shaft, a part movable along said guide, a universal joint between said guided parts and the swashmember, -a loose connection between a part of said joint and the swash-member, which -loose connection comprises a circular part, Within an encircling guide-surface, of such shape that the path of movement of the point of contact between those parts as viewed along a line parallel with the ;-axis ,of the engine, is a circle having the equation member mounted .on said crank-pin, a number r of connecting-rods for the engine pistons articulately connected to said swash-member, a number of guide means arranged to engage respectively a number of parts moving with the swash-member and which guide means are adapted to apply circular constraint to the guided parts during different parts of the cycle, so that the sum efiect of the constraints is to impart to a point on the swash-member a path of movement which when projected on to a plane at right-angles to the engine-shaft is a circle having the equation 4. A swash-plate engine comprising an engineshaft having an inclined crank-pin, a swashmember mounted on said crank-pin, a number of connecting-rods for the engine pistons, means for guiding each connecting-rod to move in a straight line parallel with the engine-shaft, a universal joint for connecting each connectingrod to the swash-member, a loose connection between two parts of said universal joint, which loose connection is adapted to permit relative movement between the parts it connects in a direction towards and away from the engineshaft and in a direction transverse to the axis of the shaft.

5. A swash-plate engine comprising an engineshaft having an inclined crank-pin, a swashmember mounted on said crank-pin, a number of connecting-rods for the engine pistons, means for guiding each connecting-rod to move in a straight line parallel with the engine-shaft, a universal joint for connecting each connectingrod to the swash-member, a loose connection between a part of the universal joint and a part of said swash-member, which loose connection is adapted to permit relative movement between the parts it connects in a direction towards and away from the engine-shaft and in a direction transverse to the axis of the shaft.

6. A swash-plate engine comprising an engineshaft having an inclined crank-pin, a swashmember mounted on said crank-pin, a number of connecting-rods for the engine pistons, means for guiding the connecting-rods to move parallel with the engine-shaft, a spherical socket connected to a connecting-rod, a ball in said spherical socket, and having a diametrically-extending slot with flat sides and a peripheral wall, a disclike part attached to the swash-member and extending into the aforesaid slot in said wall, the peripheries of which slot and disc-like member are so shaped that the point of contact between them moves in a path which as viewed along a line parallel with the axis of the engine is a circle having the equation 7. A swash-plate engine comprising an engineshaft having an inclined crank-pin, a swashmember mounted on said crank-pin, a number of connecting-rods for the engine pistons, means for guiding the connecting-rods to move parallel with the engine-shaft, a block pivotally attached to the swash-member to rock about an axis in the plane of the swash-member at right-angles to the crank-pin, a member having a slot adapted slidably to engage said block, and having a cylindrical outer surface arranged with its axis normal to the engine-shaft and to the first said axis, a part fixed to a connecting-rod and having a cylindrical socket arranged rotatably to engage said cylindrical surface, which block and slot have flat engaging faces and peripheral surfaces of such shape and size that the line of contact between them traverses a circular path having the equation 8. A swash-plate engine comprising an engineshaft having an inclined crank-pin, a swash member mounted on said crank-pin, a number of connecting rods for the engine pistons articulately connected to said swash-member, a guide extending in a direction along the engine-shaft, a part movable along said guide, a universal joint between said guided part and the swash-member, a loose connection between said guided part and a part of said universal joint, which loose connection comprises a circular cap member rotatably mounted on said part of the universal joint and a circular guide surface formed in said guided part and arranged to encircle and engage said cap member, which cap member and circular guide surface are so shaped that the path of movement of the point of contact between the cap member and the guide surface, as viewed along aline parallel with the axis of the engine, is a circle having the equation 9. A swash-plate engine comprising an engineshaft having an inclined crank-pin, a swashmember mounted on said crank-pin, a number of connecting rods for the engine pistons articulately connected to said swash-member, a guide extending in a direction along the engine-shaft, a part movable along said guide, a universal joint between said guided part and the swash-member, a loose connection between said guided part and a part of said universal joint, which loose connection comprises a cylindrical cap member rotatably mounted on said part of the universal joint and having a flat end face and a cylindrical recess in said guided part having a larger diameter than said cap member and having a flat end face, which cap member is disposed within the recess with its periphery in contact with the cylindrical wall of the recess and with its flat end face in contact with the flat face of said recess, the contours of which cap member and recess are so shaped that the path of movement of the point of contact between those part as viewed along a line parallel with the axis of, the engine is a circle having the equation CHRISTOPHER GEORGE NEVATT. FRANCIS WEST SHEARER.

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