Reciprocating fluid machines

Abstract

A scotch yoke type fluid device in which the pistons are decoupled from each other is provided. Each piston of the device has its own pair of sliding surfaces and its own slider. The sliding surface of each piston is disposed on the same side of a big end bearing of a crank. The main axis of the crank is movable along a path such that the pistons are neither substantially retarded nor advanced. The effective centre of mass of the crank, piston and slider remains stationary relative to the crank axis. Each piston includes a guide for constraining the piston to move along the piston axis. An intermediate member may interconnect the piston and the slides.

1 . A scotch yoke fluid device selected from an engine and a pump comprising:
 a crankshaft having a main axis and a big end bearing pin, the bearing pin having a bearing pin axis and being adapted to orbit the main axis during crankshaft rotation, the bearing pin sweeping a first volume centered on the main axis as it orbits the main axis;   slider connecting means rotatably mounted on the bearing pin;   a cylinder having a cylinder axis, the cylinder axis being perpendicular relative to the main axis;   a piston having a piston axis and including:   (a) a piston crown having a total cross sectional area perpendicular to the piston axis;   (b) first guide means elongate along a first axis extending perpendicular to the piston axis;   (c) restricting means elongate along a second axis extending parallel to the piston axis and the restricting means having a first end and a second end;   the piston mounted for reciprocation along the cylinder axis;   the first guide means being located only to that side of the bearing pin axis lying between the bearing pin axis and the piston crown;   the first guide means adapted to constrain the slider connecting means for reciprocation along the first guide means during crankshaft rotation;   a block comprising third guide means adapted to engage the restricting means, the restricting means and the third guide means adapted to cooperate to substantially prevent rotation of the piston around an axis parallel to the main axis   wherein:   (i) the restricting means and the third guide means are in engagement only within a second volume defined by a projection of the piston crown total cross sectional area along the piston axis towards the crankshaft;   (ii) the restricting means is positioned to a long side of the first guide means, the first end of the restricting means is located closer than the first guide means to the piston crown, and when the piston is at TDC and at BDC the second end of the restricting means is located closer to the bearing pin axis than the first guide means is; and   (iii) the restricting means is adapted to be moved in and out of the first volume such that the restricting means is completely outside the first volume when the piston is at TDC and is at least partially inside the first volume when the piston is at BDC.   
   
   
       2 . A scotch yoke fluid device according to  claim 1 , wherein the piston comprises at least two restricting means to the same long side of the first guide means and each respective restricting means is engaged by a respective third guide means. 
   
   
       3 . A scotch yoke fluid device according to  claim 1 , wherein the piston comprises at least two restricting means, there being at least one restricting means located on a long side of the first guide means and at least one other restricting means located on the opposite long side of the first guide means and each restricting means engaged by a respective third guide means. 
   
   
       4 . A scotch yoke fluid device according to  claim 1  wherein the restricting means is chosen from a group comprising a post, a rod, a tube, a bar, a web, a channel, a slot, and the third guide means comprises a bearing surface arrangement adapted for engagement with the restricting means. 
   
   
       5 . A scotch yoke fluid device according to  claim 1  wherein the first axis extends within 5° of perpendicular relative to the piston axis. 
   
   
       6 . A scotch yoke fluid device according to  claim 1  wherein in an end view the first guide means comprises opposed bearing surfaces aligned parallel to the first axis and at least one of which extends in a direction other than perpendicular to the piston axis. 
   
   
       7 . A scotch yoke fluid device according to  claim 1  wherein the engagement of the restricting means with the third guide means is such that rotation of the piston around an axis generally perpendicular to the cylinder axis is substantially prevented. 
   
   
       8 . A scotch yoke fluid device according to  claim 1  wherein the engagement of the restricting means with the third guide means is such that rotation of the first guide means around an axis parallel to the main axis is substantially prevented. 
   
   
       9 . A scotch yoke fluid device according to  claim 1  which comprises a pair of pistons in a Vee configuration having an included angle selected from 60°, 72° and 90°, each piston of the pair being mounted for reciprocation within a respective cylinder, the crankshaft being adapted to be moved along the bisector of the included angle of the Vee such that the compression ratio of each piston of the pair within their respective cylinder may be selectively raised or lowered without change of phase of either piston motion relative to crankshaft angle. 
   
   
       10 . A scotch yoke fluid device according to  claim 1  which comprises a pair of pistons in a Vee configuration of cylinders, each piston of the pair being mounted for reciprocation within a respective cylinder, the crankshaft being adapted to be moved along a path such that the compression ratio of each piston of the pair within its respective cylinder may be selectively raised or lowered without change of phase of either piston motion relative to crankshaft rotation. 
   
   
       11 . A scotch yoke fluid device according to  claim 1  wherein the slider connecting means comprises adjustable slider means, and hydraulic ram means adapted to selectively raise or lower the adjustable slider means relative to the cylinder to alter the compression ratio of the respective piston in the cylinder. 
   
   
       12 . A scotch yoke fluid device according to  claim 1  wherein the slider connecting means comprises adjustable slider means, and hydraulic ram means adapted to vary the angle of the adjustable slider means relative to the cylinder. 
   
   
       13 . A scotch yoke fluid device according to  claim 1  comprising intermediate connecting means interconnecting the piston crown with the first guide means; and means including a compressible connecting rod for adjusting the distance along the cylinder axis over which the piston may travel. 
   
   
       14 . A scotch yoke fluid device according to  claim 1  in which the piston crown and the restricting means are each parts of a multi-part piston including intermediate connecting means interconnecting the piston crown of the multi-part piston with the first guide means of the multi-part piston. 
   
   
       15 . A scotch yoke fluid device according to  claim 1  in which the piston crown and the restricting means are each parts of a multi-part piston, and at least the piston crown of the multi-part piston is pivotably mounted to at least one of the other parts of the multi-part piston. 
   
   
       16 . A scotch yoke fluid device according to  claim 2  wherein the restricting means is chosen from a group comprising a post, a rod, a tube, a bar, a web, a channel, a slot, and the third guide means comprises a bearing surface arrangement adapted for engagement with the restricting means. 
   
   
       17 . A scotch yoke fluid device according to  claim 2  wherein the first axis extends within 5° of perpendicular relative to the piston axis. 
   
   
       18 . A scotch yoke fluid device according to  claim 2  wherein in an end view the first guide means comprises opposed bearing surfaces aligned parallel to the first axis and at least one of which extends in a direction other than perpendicular to the piston axis. 
   
   
       19 . A scotch yoke fluid device according to  claim 2  wherein the engagement of the restricting means with the third guide means is such that rotation of the piston around an axis generally perpendicular to the cylinder axis is substantially prevented. 
   
   
       20 . A scotch yoke fluid device according to  claim 2  wherein the engagement of the restricting means with the third guide means is such that rotation of the first guide means around an axis parallel to the main axis is substantially prevented. 
   
   
       21 . A scotch yoke fluid device according to  claim 2  which comprises a pair of pistons in a Vee configuration having an included angle of 60°, 72° or 90°, each piston of the pair being mounted for reciprocation within a respective cylinder, the crankshaft being adapted to be moved along the bisector of the included angle such that the compression ratio of each piston of the pair within their respective cylinder may be selectively raised or lowered without change of phase of either piston motion relative to crankshaft rotation. 
   
   
       22 . A scotch yoke fluid device according to  claim 2  which comprises a pair of pistons in a Vee configuration of cylinders, each piston of the pair being mounted for reciprocation within a respective cylinder, the crankshaft being adapted to be selectively moved along a path such that the compression ratio of each piston of the pair within their respective cylinder may be selectively raised or lowered without change of phase of either piston motion relative to crankshaft rotation. 
   
   
       23 . A scotch yoke fluid device according to  claim 2  wherein the slider connecting means comprises adjustable slider means, and hydraulic ram means adapted to selectively raise or lower the adjustable slider means relative to the cylinder to selectively alter the compression ratio of the respective piston in the cylinder. 
   
   
       24 . A scotch yoke fluid device according to  claim 2  wherein the slider connecting means comprises adjustable slider means, and hydraulic ram means being adapted to selectively vary the angle of the adjustable slider means relative to the cylinder. 
   
   
       25 . A scotch yoke fluid device according to  claim 2  further comprising intermediate connecting means interconnecting the piston crown with the first guide means; and means including a compressible connecting rod for adjusting the distance along the cylinder axis over which the piston may travel. 
   
   
       26 . A scotch yoke fluid device according to  claim 2  in which the piston crown and the restricting means are each parts of a multi-part piston including intermediate connecting means interconnecting the piston crown of the multi-part piston with the first guide means of the multi-part piston. 
   
   
       27 . A scotch yoke fluid device according to  claim 2  in which the piston crown and the restricting means are each parts of a multi-part piston, and at least the piston crown of the multi-part piston is pivotably mounted to at least one of the other parts of the multi-part piston. 
   
   
       28 . A scotch yoke fluid device according to  claim 3  wherein the restricting means is chosen from a group comprising a post, a rod, a tube, a bar, a web, a channel, a slot, and the third guide means comprises a bearing surface arrangement adapted for engagement with the restricting means. 
   
   
       29 . A scotch yoke fluid device according to  claim 3  wherein the first axis extends within 5° of perpendicular relative to the piston axis. 
   
   
       30 . A scotch yoke fluid device according to  claim 3  wherein in an end view the first guide means comprises opposed bearing surfaces parallel to the first axis and at least one of which extends in a direction other than perpendicular to the piston axis. 
   
   
       31 . A scotch yoke fluid device according to  claim 3  wherein the engagement of the restricting means with the third guide means is such that rotation of the piston around an axis generally perpendicular to the cylinder axis is substantially prevented. 
   
   
       32 . A scotch yoke fluid device according to  claim 3  wherein the engagement of the restricting means with the third guide means is such that rotation of the first guide means around an axis parallel to the main axis is substantially prevented. 
   
   
       33 . A scotch yoke fluid device according to  claim 3  which comprises a pair of pistons in a Vee configuration having an included angle selected from 60°, 72° and 90°, each piston of the pair mounted for reciprocation within a respective cylinder, the crankshaft being adapted to be selectively moved along the bisector of the included angle such that the compression ratio of each piston of the pair within their respective cylinder may be selectively raised or lowered without change of phase of either piston motion relative to crankshaft rotation. 
   
   
       34 . A scotch yoke fluid device according to  claim 3  which comprises a pair of pistons in a Vee configuration of cylinders, each piston of the pair being mounted for reciprocation within a respective cylinder, the crankshaft being adapted to be selectively moved along a path such that the compression ratio of each piston of the pair of piston within its respective cylinder may be selectively raised or lowered without change of phase of either piston motion relative to crankshaft rotation. 
   
   
       35 . A scotch yoke fluid device according to  claim 3  wherein the slider connecting means comprises adjustable slider means, and hydraulic ram means being adapted to selectively raise or lower the adjustable slider means relative to the cylinder to selectively alter the compression ratio of the respective piston in the cylinder. 
   
   
       36 . A scotch yoke fluid device according to  claim 3  wherein the slider connecting means comprises adjustable slider means, and hydraulic ram means adapted to selectively vary the angle of the adjustable slider means relative to the cylinder. 
   
   
       37 . A scotch yoke fluid device according to  claim 3  further comprises intermediate connecting means interconnecting the piston crown with the first guide means; and means including a compressible connecting rod for adjusting the distance along the cylinder axis over which the piston may travel. 
   
   
       38 . A scotch yoke fluid device according to  claim 3  in which the piston crown and the restricting means are each parts of a multi-part piston including intermediate connecting means interconnecting the piston crown of the multi-part piston with the first guide means of the multi-part piston. 
   
   
       39 . A scotch yoke fluid device according to  claim 3  in which the piston crown and the restricting means are each parts of a multi-part piston, and at least the piston crown of the multi-part piston is pivotably mounted to at least one of the other parts of the multi-part piston. 
   
   
       40 . A scotch yoke fluid device according to  claim 1  wherein the crankshaft is adapted to be moved along a path which is transverse relative to the cylinder axis such that the compression ratio of the piston within the cylinder may be selectively raised or lowered without change of phase of the piston motion relative to crankshaft rotation. 
   
   
       41 . A scotch yoke fluid device according to  claim 2  wherein the crankshaft is adapted to be selectively moved along a path which is transverse relative to the cylinder axis such that the compression ratio of the piston within the cylinder may be selectively raised or lowered without change of phase of the piston motion relative to crankshaft rotation. 
   
   
       42 . A scotch yoke fluid device according to  claim 3  wherein the crankshaft is adapted to be selectively moved along a path which is transverse relative to the cylinder axis such that the compression ratio of the piston within the cylinder may be raised or lowered without change of phase of the piston motion relative to crankshaft rotation. 
   
   
       43 . A scotch yoke fluid device according to  claim 1  in which the piston crown and the restricting means are each parts of a multi-part piston including intermediate connecting means interconnecting the piston crown of the multi-part piston with the first guide means of the multi-part piston, the intermediate connecting means including restricting means adapted for engagement with third guide means within the second volume and the third guide means being adapted to be selectively moved in a transverse direction to the cylinder axis. 
   
   
       44 . A scotch yoke fluid device according to  claim 2  in which the piston crown and at least one of the at least two restricting means are each parts of a multi-part piston including intermediate connecting means interconnecting the piston crown of the multi-part piston with the first guide means of the multi-part piston, the intermediate connecting means including restricting means being adapted for engagement with third guide means within the second volume and the third guide means being adapted to be selectively moved in a transverse direction to the cylinder axis. 
   
   
       45 . A scotch yoke fluid device according to  claim 3  in which the piston crown and at least one of the at least two restricting means are each parts of a multi-part piston including intermediate connecting means interconnecting the piston crown of the multi-part piston with the first guide means of the multi-part piston, the intermediate connecting means including restricting means adapted for engagement with third guide means within the second volume and the third guide means being adapted to be selectively moved in a transverse direction to the cylinder axis. 
   
   
       46 . A scotch yoke fluid device according to  claim 1  wherein the first guide means further comprising a plain bearing. 
   
   
       47 . A scotch yoke fluid device according to any one of  claim 1  wherein the first guide means further comprising a roller bearing. 
   
   
       48 . A scotch yoke fluid device according to any one of  claim 1  wherein the engagement of a restricting means with a third guide means further comprises a roller bearing. 
   
   
       49 . A scotch yoke fluid device according to any one of  claim 1  wherein the engagement of a restricting means with a third guide means further comprises a plain bearing.