GB1566832A - Steam engines - Google Patents

Description

(54) IMPROVEMENTS RELATING TO STEAM ENGINEES (71) We, J. WARNE CARTER, SR, of 4520 Weeks Park Lane, Wichita Falls, Texas 76308, United States of America and J.

WARNE CARTER, JR, of P.O. Box 684, Burkburnett, Texas 76354, United States of America, both citizens of the United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to steam engines, and more particularly to improvements in poppet valves for high speed steam engines.

The main object of the invention is to provide a steam engine having an improved poppet valve structure with a substantial degree of cutoff and wherein there is high valve impact velocity, the improved structure being relatively simple, employing a minimum number of parts, and reducing the amount of stress on the parts during operation.

According to the present invention, there is provided a steam engine, comprising a cylinder containing a reciprocable piston, a steam admission chamber communicating with the cylinder through a circular valve port in an end wall of the cylinder, an annular surface portion of the end wall surrounding the port and forming a valve seat in said chamber, a valve element in the chamber having an annular sealing surface to engage the valve seat, spring means biasing the valve element into a seated position to close the valve port, and a relatively rigid valve lifter member fixed to an uppermost portion of the piston, the piston, the valve element, spring means and valve lifter member being disposed on a common longitudinal axis, the lifter member having an abutment surface for engaging a cooperable surface on the valve element to unseat the valve element against the force of said spring mean ;r open the valve port, the spring means having sufficient strength to maintain the abutment surface and the cooperable surface in engàbevnent while the valve element is unseated, said abutment surface and said cooperable surface comprising nonplanar conforming surfaces of revolution coaxially related to said valve seat, whereby the sealing surface of the valve element is maintained both parallel to and centered in relationship to the valve seat in the seating of the valve element. The steam engine poppet valve structure has the advantage that the components possess low mass thus reducing the inertia effects.

Furthermore, the lifter element and the valve element can have matching or conforming configurations for optimum sealing action and uniform deceleration force distribution, the centering action thus provided preventing the valve element from floating away from the associated lifter element.

To reduce impact stresses, annular recesses may be formed in the end wall of the cylinder to provide resiliency in the region of the valve seat, and the lifter member may comprise a resilient body.

The clearance volume of the cylinder may be adjusted manually or automatically to regulate the horsepower output and efficiency of the engine.

The invention is illustrated by way of example in the fficcompanying drawings in which, Figure i is a vertical cross-sectional view taken through the upper portion of a cylinder of a steam engine according to the present invention and showing one form of poppet valve structure, the valve element being shown in its seated position.

Figure 2 is a vertical cross-sectional view similar to that of Figure 1 but showing the valve element in open position at the top end of the stroke of the associated piston.

Figure 3 is a side elevational view showing the valve disc and lifter elements of the valve structure of Figures 1 and 2.

Figure 4 is a vertical cross-sectional view similar to Figure 1, but showing a modified form of poppet valve structure.

Figure 5 is a horizontal cross-sectional view taken substantially on line 5-5 of Figure 4.

Figure 6 is a side elevational view of the valve lifter element employed in the embodi ment of Figure 4.

Figure 7 is a fragmentary vertical cross sectional view showing another form of valve element.

Figure 8 is a fragmentary vertical cross sectional view showing still another form of valve element.

Figure 9 is a fragmentary vertical cross sectional view showing an additional form of valve element.

Figure 10 is a fragmentary vertical crosssectional view showing a still further form of valve element.

A prime purpose of the present invention is to provide practical and improved poppet valve structures in a high speed steam engine wherein the piston speed is relatively high, for example, of the order of twenty-five hundred feet per minute, and with substantial cutoff, for example, of the order of three per cent. Under these conditions, with previously employed valve structures, the impact at which the piston strikes the valve would be very great and the stresses generated under these conditions would be dangerously excessive. Generally speaking, the impact stresses are functions of the piston speed, the degree of cutoff and the mass of the associated valves. Previously employed structures have employed round valve balls, and such valve balls have considerable mass and substantial inertia relative to the amount of valve opening generated with a given lift.As the ball size increases, the inertia likewise increases, the increase being at a much faster rate than the valve opening. Thus, with the round ball valve, the impact velocity must be kept low because of the inertia effects of such a valve. Impact stresses increase approximately with the square of the impact velocity. Thus, when the impact velocity is doubled, the impact stresses will increase approximately four times.

The present invention aims to provide a valve system designed to operate at piston speeds of the order of twenty-five hundred feet per minute with cutoff of approximately three percent without exceeding the endurance limit of the valve material at elevated temperatures, for example, of the order of 9500 F. The structure of the present invention employs a valve element of relatively low mass to reduce inertia effects, and the lifter element or member and the valve element are arranged to have matching or conforming interfitting configurations so that when the valve element returns to its seat, it will be in proper position for sealing purposes and so that the deceleration forces will be substantially uniformly distributed.The valve structure employs a relatively strong spring acting on the valve element to force the valve element to remain centered and aligned on top of the associated lifter element during the operation of the valve. Thus, the maximum acceleration of the associated piston occurs at top dead center and there would be a natural tendency for the valve element to float away from its lifter during closing action of the valve.

This would cause a tendency for the valve element to engage its seat at an improper angle and with a much higher velocity than if it were constrained to follow its associated lifter element, due to the pressure differential across the valve element. The matching interfitting configuration employed between the valve element and its lifter is preferably conical in the structure of the present invention for minimizing the above-described tendency for improper valve action. The cone-shaped valve element is also the most efficient structural design which allows for a lighter valve element with minimum inertia.

The structure of the present invention further aims to decrease impact stress by employing a lifter element and valve seat which are somewhat resilient and which are allowed to have a small deflection. This small deflection greatly reduces impact stresses since the valve element itself can be accelerated and decelerated with some yielding action instead of with unyielding impact.

Referring to the drawings, and more particularly to Figures 1 and 2, 11 generally designates a cylinder of a high speed steam engine of the type contemplated in the present invention, the cylinder being provided with the top cylinder head portion 12 which provides the end wall 1 2a of the cylinder and which is threadedly secured on the lower cylinder body portion 13, employing an annular sealing gasket 14 between the head portion 12 and the body portion 13.

A piston 15 reciprocates in the cylinder and a valve lifter member or element 17 is centrally mounted in or fixed to the uppermost portion or top face of the piston 15, the lifter member 17 having a threaded shank 18 which is threadedly engaged centrally in the top piston portion. The lifter member has a hexagonal flange 19 which is engageable with the top face of the piston and the lifter member is further provided with a surface of revolution in the form of an upwardly convergent conical top portion or abutment surface 20.

The head portion 12 has a steam admission chamber 21 and is further provided with a threaded cover cap 22 axially aligned with cylinder 13 and formed with a downwardly facing annular recess 23 which provides a seat for one end of a relatively strong coiled compression spring 24, the other end of the coiled spring bearing on a valve disc member or element 25 in the chamber which has a surface of revolution in the form of a conical bottom surface or recess 26 matching and conformingly engaging with the conical top portion 20 of lifter member 17. The disc-shaped valve element 25 is provided with the flag marginal peripheral portion 27 defining a seat for the bottom end portion of the biasing spring 24.

The valve disc 25 is further provided with a downwardly convergent annular frustoconical bottom face or sealing surface 28 which is engageable with the correspondingly shaped end wall surface or valve seat 29 provided in chamber 21 surrounding the circular valve passage or port 30 which is located in end wall 12a immediately above the center portion of piston 15 to provide communication between the chamber and the cylinder, as is clearly shown in Figure 1. Abutment surface 20 of the lifter member and cooperable surface 26 of the valve element are concentric with sealing surface 28 of the valve element and valve seat 29.

The conforming surfaces of revolution 20 and 26 are coaxially related to the valve seat 29, and with the spring means 24 having sufficient strength to maintain these conforming surfaces in engagement while the valve element 25 is unseated, whereby the sealing surface 28 of the valve element is maintained both parallel to and centered in relationship to the valve seat 29 in the seating of the valve element 25.

Figure 1 shows the valve element 25 biased into seated position by spring 24 for closing the valve port before lifter 17 has risen to its valveopening position. Figure 2 shows piston 15 substantially in its uppermost position with the lifter element 17 engaged in the recess 26 and causing the valve element 25 to be lifted against the force of spring 24 to its open position wherein fluid can pass through the valve passage 30. As the piston descends, the valve element 25 moves downwardly to the seating position of Figure 1, causing cutoff.

The generally conical-shaped valve element 25 has relatively small mass so that the inertia effects are minimized, and the spring 24 holds the valve element 25 in proper position for effective sealing as it returns toward engagement with the seat 29, and is held in the proper position so that deceleration forces will be uniformly distributed. The spring 24, acting concentrically with surfaces 26 and 28 of the valve element, forces the valve element 25 to remain on top of the lifter element 17 during the operation of the valve and maintains the generally conical member 25 in properly centered position during its closing.In other words, the spring has sufficient strength to maintain surface 26 of the valve element 25 in engagement with abutment surface 20 of lifter member 17 in both the unseating and seating of the valve element to ensure that the sealing sur face 28 of the valve element is both parallel to and centered in relationship to the valve seat 29 in the seating of the valve element. Since the impact forces generated by the seating of the valve element 25 are distributed substantially uniformly over the sealing surface 28, the valve element will sustain minimum damage and will operate over long periods of time.

The modification shown in Figures 4, 5 and 6 represents a further means for decreasing the impact stress on the valve element and associa ted parts of the high speed valve assembly. In the modified structure of Figures 4 through 6, a head member 12' is threadably engaged on the cylinder body 13' and a resilient end wall or valve seat member 31 is interposed between the head member 12' and the top rim of the cylinder body 13'. To provide resiliency in the region of valve seat 29, the valve seat member 31 is generally annular in shape and is annularly corrugated by the provision therein of concen tric recesses or channels 32 and 33 respectively facing downwardly and upwardly, as shown in Figure 4, the recesses being concentric with the central fluid passage 30' defined by the annular valve seat member 31.The member 31 is provided with the relatively rigid cylindrical outer skirt portion 34 which is equal in diameter and shape with the top rim portion of the cylinder body 13' and which is clamped thereto by the head member 12'. Annular sealing gaskets 36 and 37 are provided in respective annular recesses 38 and 39 formed in the rim portion of member 13' and of member 31 to seal the member 31 relative to the parts adjacent thereto, namely, relative to the rim of cylinder body 13' and the adjacent portion of head member 12'.

It will be noted that while the outer portion 34 of the valve seat member 31 is rigidly clamped, the annularly corrugated inner portion thereof is free to flex somewhat to provide a valve cushioning action, as will be presently described.

Head member 12' is provided with a central cap portion 22, formed with a downwardly facing annular spring seat 23 which receives the top end of the valve biasing spring 24. The bottom end of the biasing spring 24 bears on a valve element 25 similar to that employed in the embodiment of Figures 1 and 2, biased downwardly toward engagement with the downwardly convergent frusto-conical seat portion 29 of member 31. The bottom conical surface or recess of the valve element 25 is engageable by the similarly shaped top conical abutment surface 20' of a valve lifter member or element 17' threadedly, fixedly secured centrally in the top wall or face of the piston 15'.As shown in Figure 6, the member 17' is an elongated body which is generally cylindrical in shape and provided with male threads 37' on its upper portion which are threadedly engaged in correspondingly shaped female threads provided in a central opening in the top wall or face of piston 15' which receives the lifter member 17', the member 17' having a stop flange 38' located above the threads 37'. The member 17' is annularly recessed as shown at 40 to define an outer sleeve portion 40a having its end fixed to the piston and a central downwardly tapering central column member 41 of substantial height, formed at its top end with the hexagonal head portion 42 having the upwardly tapering conical lifter face or abutment surface 20' which projects from the face of the piston.

As shown in Figure 4, the column element 41 is integral with the main body of member 17' and is of substantial height and has substantial elasticity. Also, the relatively thin outer sleeve portion of member 17' is resiliently yieldable in tension. Thus, the lifter member can resiliently deform responsive to downward force exerted thereon and acts as a cushioning element when downward impact force is applied thereto, whereby it reduces the magnitude of impact stresses developing both on the lifter portion of the assembly and the valve element 25 contacted by the lifter element as it rises to open the valve. When the valve element descends, to engage seat 29, the annularly resilient seat 31 cushions the descent of the valve element 25 thereagainst and likewise acts to reduce impact stresses generated by the seating of the valve element on the seat 29.The valve seat member 31 thus acts as a strong spring, and may have a maximum deflection at its central portion of the order of .0015 inch. This small deflection serves to greatly reduce the impact stresses, since the allowable movement of the valve element 25 under impact develops a much smaller net maximum stress than would be generated in the case of solid unyielding impact.

Similarly, the column element 41 is resiliently yieldable to some extent in compression and the cylindrical outer portion of member 17' is yieldable in tension in the manner abovedescribed. The conical engaging or abutment surface portion 20' has a resilient connection to the top wall of the piston 15' and therefore the lifter element is slightly yieldable to provide a cushioning action which again serves to reduce the maximum stresses generated as a result of impact with the valve element 25.

As in the previously described embodiment of the invention shown in Figures 1 and 2, the conical lifter or abutment portion 20' co operates with the conformably shaped conical bottom surface or recess in the conical valve element 25 and with the centering spring 24 to properly position the valve element 25 so that stresses generated by the contact of its sealing surface with the valve seat 29 are distributed in a substantially uniform manner around the conical valve element, and so that satisfactory and positive sealing action is obtained.

It will be noted that from Figures 4 and 6 the hexagonal top flange portion 42 of the column portion 41 of lifter member 17' is normally spaced a short distance above the stop flange 38' of member 17', said distance being sufficient to allow for the above-described resilient deflection of member 17' generated by impact of abutment surface 20' with the conical valve element 25 during operation of the high speed engine. The resiliency of the lifter element 17' combined with the resiliency of the valve seat member 31 provides substantial reduction in the stress generated in the conical valve element 25 as it is engaged by conical element 20' for lifter action and as it descends to engage seat 29 for valve cutoff action.

Figure 7 shows a modification wherein the valve element shown at 101 has a downwardly convergent conical bottom surface or face 102 having a central portion receivable in a matching conical recess or abutment surface in the lifter element 103 and an outer annular portion engageable with conical valve seat 29. The valve element is provided with an annular seat 104 which receives the bottom coil of the biasing spring 24.

Figure 8 shows another modification wherein the valve element shown at 105 has an upwardly convergent conical central body portion 106 defining a conical bottom recess or abutment surface which receives the matching or conforming conical top end surface 107 of the valve lifter element shown at 108. The valve element 105 has a flat annular peripheral seat 109 on which the bottom coil of the biasing spring 24 bears.

Figure 9 shows another modification wherein the conforming engageable surfaces of revolution which provide the abutment surface of the lifter member and the cooperable surface of the valve element comprise spherical surfaces.

Specifically, the valve element, shown at 110, has a generally hemispherical, downwardly concave main body portion 111 which receives the spherically curved matching top end portion 112 of the valve lifter element 113. A peripheral flange 114 formed integrally with said main body portion provides a seat for the bottom coil of the biasing spring 24.

In the forms shown in Figures 8 and 9, the valve elements have flat or planar annular bottom sealing surfaces 115 cooperating with mating flat annular seats provided around the central fluid passages shown respectively at 116 and 117.

Figure 10 shows still another modification wherein the valve element, shown at 120, is in the form of a hollow ball or sphere and is sealingly receivable in a spherically curved annular seat 121 provided around the fluid flow passage 30. The lifter element 122 is formed with a matching spherically curved recess 123, and the bottom coil of the biasing spring 24 bears on the top of the hollow ball member 120 opposite the lifter element 122.

As in the case of the previously described valve elements, the hollow ball valve element 120 has a high degree of structural efficiency which enables it to be relatively light and thus to have relatively low inertia. The valve element may be elliptical in vertical cross section rather than circular.

The above-described steam admission valves may have constant cutoff or, if desired, means may be provided for varying the clearance volume of the cylinders associated with such valves. By varying the clearance volume, it is possible to increase or decrease the amount of steam admitted to the top of the cylinder, depending upon the horsepower or efficiency required of the associated motor. A large clearance volume will increase the power developed by the engine, while a small clearance volume will increase the efficiency thereof.

WHAT WE CLAIM IS: 1. A steam engine, comprising a cylinder containing a reciprocable piston, a steam admission chamber communicating with the cylinder through a circular valve port in an end wall of the cylinder, an annular surface portion of the end wall surrounding the port and forming a valve seat in said chamber, a valve element in the chamber having an annular sealing surface to engage the valve seat, spring means biasing the valve element into a seated position to close the valve port, and a relatively rigid valve lifter member fixed to an uppermost portion of the piston, the piston, the valve element, spring means and valve lifter member being disposed on a common longitudinal axis, the lifter member having an abutment surface for engaging a cooperable surface on the valve element to unseat the valve element against the force of said spring means to open the valve port, the spring means having sufficient strength to maintain the abutment surface and the cooperable surface in engagement while the valve element is unseated, said abutment surface and said cooperable surface comprising non-planar conforming surfaces of revolution coaxially related to said valve seat, whereby the sealing surface of the valve element is maintained both parallel to and centered in relationship to the valve seat in the seating of the valve element.

2. A steam engine as set forth in Claim 1, wherein said abutment surface and said cooperable surface comprise spherical surfaces.

3. A steam engine as set forth in Claim 2, wherein the valve element comprises a hollow sphere.

4. A steam engine as set forth in Claim 1, wherein said abutment surface and said cooperable surface comprise conical surfaces.

5. A steam engine as set forth in Claim 4, wherein said co-operable surface and said sealing surface comprise portions of a conical surface of the valve element.

6. A steam engine as set forth in Claim 1, wherein said valve seat and said sealing surface comprise planar surfaces.

7. A steam engine as set forth in Claim 1, wherein the spring means comprises a coiled compression spring acting substantially coaxially with said cooperable surface and said sealing surface of the valve element.

8. A steam engine as set forth in Claim 1, wherein the end wall of the cylinder has an annular recess substantially concentric with the valve seat for providing resiliency in the end wall in the region of the valve seat.

9. A steam engine as set forth in Claim 1, wherein the relatively rigid lifter member is mounted to deflect in compression, the face of the element providing said abutment surface.

10. A steam engine as set forth in Claim 1 wherein the lifter member comprises a generally cylindrical elongated body having an annular recess formed therein to provide an outer sleeve portion and a central column portion, the base of the column portion being connected to said sleeve portion, the body being received by an opening in the face of the piston with an end of the sleeve portion being fixed to the piston, and wherein the central column portion projects from the face of the piston and provides said abutment surface.

11. A steam engine as set forth in Claim 1, wherein the valve element is generally discshaped.

12. A steam engine as set forth in Claim 4, wherein the valve element is generally discshaped.

13. A steam engine substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (13)

**WARNING** start of CLMS field may overlap end of DESC **. which enables it to be relatively light and thus to have relatively low inertia. The valve element may be elliptical in vertical cross section rather than circular. The above-described steam admission valves may have constant cutoff or, if desired, means may be provided for varying the clearance volume of the cylinders associated with such valves. By varying the clearance volume, it is possible to increase or decrease the amount of steam admitted to the top of the cylinder, depending upon the horsepower or efficiency required of the associated motor. A large clearance volume will increase the power developed by the engine, while a small clearance volume will increase the efficiency thereof. WHAT WE CLAIM IS:

1. A steam engine, comprising a cylinder containing a reciprocable piston, a steam admission chamber communicating with the cylinder through a circular valve port in an end wall of the cylinder, an annular surface portion of the end wall surrounding the port and forming a valve seat in said chamber, a valve element in the chamber having an annular sealing surface to engage the valve seat, spring means biasing the valve element into a seated position to close the valve port, and a relatively rigid valve lifter member fixed to an uppermost portion of the piston, the piston, the valve element, spring means and valve lifter member being disposed on a common longitudinal axis, the lifter member having an abutment surface for engaging a cooperable surface on the valve element to unseat the valve element against the force of said spring means to open the valve port, the spring means having sufficient strength to maintain the abutment surface and the cooperable surface in engagement while the valve element is unseated, said abutment surface and said cooperable surface comprising non-planar conforming surfaces of revolution coaxially related to said valve seat, whereby the sealing surface of the valve element is maintained both parallel to and centered in relationship to the valve seat in the seating of the valve element.

2. A steam engine as set forth in Claim 1, wherein said abutment surface and said cooperable surface comprise spherical surfaces.

3. A steam engine as set forth in Claim 2, wherein the valve element comprises a hollow sphere.

4. A steam engine as set forth in Claim 1, wherein said abutment surface and said cooperable surface comprise conical surfaces.

5. A steam engine as set forth in Claim 4, wherein said co-operable surface and said sealing surface comprise portions of a conical surface of the valve element.

6. A steam engine as set forth in Claim 1, wherein said valve seat and said sealing surface comprise planar surfaces.

7. A steam engine as set forth in Claim 1, wherein the spring means comprises a coiled compression spring acting substantially coaxially with said cooperable surface and said sealing surface of the valve element.

8. A steam engine as set forth in Claim 1, wherein the end wall of the cylinder has an annular recess substantially concentric with the valve seat for providing resiliency in the end wall in the region of the valve seat.

9. A steam engine as set forth in Claim 1, wherein the relatively rigid lifter member is mounted to deflect in compression, the face of the element providing said abutment surface.

10. A steam engine as set forth in Claim 1 wherein the lifter member comprises a generally cylindrical elongated body having an annular recess formed therein to provide an outer sleeve portion and a central column portion, the base of the column portion being connected to said sleeve portion, the body being received by an opening in the face of the piston with an end of the sleeve portion being fixed to the piston, and wherein the central column portion projects from the face of the piston and provides said abutment surface.

11. A steam engine as set forth in Claim 1, wherein the valve element is generally discshaped.

12. A steam engine as set forth in Claim 4, wherein the valve element is generally discshaped.

13. A steam engine substantially as hereinbefore described with reference to and as shown in the accompanying drawings.