US3747338A

US3747338A - Power plant

Info

Publication number: US3747338A
Application number: US00185781A
Authority: US
Inventors: E Tapp
Original assignee: County Commercial Cars Ltd
Current assignee: County Commercial Cars Ltd
Priority date: 1970-10-06
Filing date: 1971-10-01
Publication date: 1973-07-24
Anticipated expiration: 1990-07-24
Also published as: GB1336167A; GB1352510A

Abstract

The invention consists of a power plant comprising a fluid heater with an inlet and an outlet for the fluid, at least one piston and cylinder combination having an associated inlet valve for admitting fluid to the cylinder and, means to connect the outlet with the inlet valve, in which there is a chamber around a part of the valve through which chamber fluid passes to the cylinder and there is means to direct heated fluid from the chamber back to the heater to provide a continuous circuit.

Description

11 m 1/ 1: r I t Rte Stes Patent 1 1 1 Ta 1 1 .1 197 POWER PLANT 3,035,557 5/1962 Litwinofl 60/108 R Inventor: Ernest Thomas James m Fleet 3,358,450 12/1967 Schroedter et a1. 60/105 Alder-shot, gland FOREIGN PATENTS 01R APPLICATIONS [73] Assignee: County Commercial Cars Limit ed, 1,055,989 1/1967 Great Britain 60/105 Aldershot, Hempshire, England 22 Filed: Oct 1 971 Primary Examiner--Martin P. SChWKdl'Ol'l Assistant Examiner-Allen M. Ostrager PP 185,781 Attorney-Irvin S." Thompson et a1.

[30] Foreign Application Priority Data [57] ABSTRACT Oct. 6, 1970 Great Britain 47,547/70 The Invention cons1sts of a power plant compr1s1ng a 52 us. (:1 60/69 60/1 60/92 fluid heater with an inlet and the fluid 2 I418 least one piston and cylinder combination having an as- 51 Int. 01. F01b 29/12 FOlb 29/02 Miami inlet valve admitting fluid the cylinder [58] 1 1610 61 Search 60/27 105 10s with the inlet valve 6 f in which there is a chamber around a part of the valve through which chamber fluid passes to the cylinder and 56] References Cited there is means to direct heated fluid from the chamber UNITED STATES PATENTS back to the heater to provide a continuous circuit. 3,021,824 2/1962 Profos 122/406 ST 13 Claims, 7 Drawing Figures PAIimiuJuLzmla SHEEI [If 4 rowan PLANT The invention relates to power plant, for example, high power to weight ratio power plant for use in powering vehicles.

The invention provides power plant comprising a fluid heater with an inlet and an outlet for the fluid, at least one piston and cylinder combination having an associated inlet valve for admitting fluid to the cylinder and, means to connect the outlet with the inlet valve, in which there is a chamber around a part of the valve through which chamber fluid passes to the cylinder and there is means to direct heated fluid from the chamber back to the heater.

Preferably the heated fluid is water or steam (the word steam is intended to include steam above its critical point) although the fluid could be any other vapour or gas.

Preferably the arrangement is such that heated water from the outlet flashes to steam when it is admitted to the cylinder through the control valve.

A by-pass may be provided so that fluid can flow between the heated inlet and outlet without passing through the chamber, a diverter valve being provided downstream of the chamber to direct fluid either to the chamber of the by-pass.

The diverter valve may be arranged to operate gradually whereby the fluid may be directed to the by-pass and the chamber in any desired proportion.

A non-return valve may be provided downstream of the chamber to prevent fluid from the by-pass from entering the chamber.

The heater may comprise a coiled tube, having heating means which may comprise a gas or liquid fuel burner arranged to heat the tube.

A temperature sensitive device may be provided in the said continuous circuit to control the heating means automatically.

' By way of example, some specific embodiments of the invention will now be described, with reference to the accompanying drawing, in which:

FIG. 1 is a diagrammatic view of one form of steam power plant according to the invention;

. FIG. 2 is a section through an alternative form of heater;

FIG. 3 is a view of part of a heater;

FIG. 4 shows a section through part of a cylinder and valve, and also shows diagrammatically a means for controlling the valve;

FIGS. 5 and 6 show alternative means for controlling the valve of FIG. 4; and

FIG. 7 shows a variation of the embodiment shown in FIG. 1.

The plant shown in FIG. 1 comprises a heater 10, a burner 9, water supply means 11, three cylinders l2, 13, 14 each having an associated piston (see FIG. 4), and associated valves in chambers l5, 16, 117 a pump 18 and fuel control means 119.

The water supply means comprises a pump 20 and a pressure sensitive control device 21. The device 21 controls the supply of water from a supply tank (not shown) to heater by deflecting the supply from pump either to the heater or back to the pump or supply tank via by-pass pipe 22, as required. The control device 21, could also comprise a safety release valve to permit the flow of fluid-back through the device under excess pressure.

The heater comprises a casing 23 housing a coiled tube 24. The coil 24 is made up of a series of coil elements 25 (see FIG. 3) each element extending horizontally. The coil elements are alternately of left and right hand spiral form and are arranged one on top of the other to form a vertical coil as shown in FIG. 1, theelements interlocking as shown and being connected to gether to provide a continuous length of coiled tube. The connections between the elements are accessible through doors (not shown) in casing 23. The elements are supported on cross bars comprising tubes 26 located in a frame 27 The arrangement is such that in the gas space the elements do not touch or substantially obscure one another, so that a large unobstructed surface area is presented to the combustion gases from the burner 9.

The water supply means 11 are connected to the inlet endof the heater tube. An outlet provided in the hottest coil in the tube is connected via the thermostatic control 19 to the chambers l5, l6, 17 in series (or in parallel if desired). A conduit 28 defines a fluid passage which runs from the chambers via a pump 18 back to an inlet in the hottest element 29 of the heater, although the inlet could be in any element. Fuel is sup plied to burner 9 through a pipe 30 which pipe passes is controlled by the thermostatic control 19 which may be of any suitable (e.g., electrical or mechanical) type.

Referring now to FIG. 4 there is shown part of one cylinder 40 and its associated piston and valve gear. At the lower end of the piston there is a recess 44, into which is fitted a dome shaped member 42. The space 44 above the dome comprises an air space or a vacuum to restrict heat flow to the piston, in order to protect its sliding surfaces. The space may be filled with insulating material to assist restriction of heat flow.

The cylinder head 61 houses the valve. A valve chamber 41 which corresponds to the chambers 15, 16 17 in FIG. 1 is formed in the head 61 and together with the region 43 within the dome forms the expansion chamber into which fluid flows. The valve member comprises a valve stem 47 and a valve head comprising a cylindrical member 48 and a poppet 45. The member 48 slides in a bore '76 in the cylinder head 61 and the stem 47 slides in extension 71 of the head 61. A spring 72 acts between a shoulder 73 on the head 611 and an abutment 74 on the valve stem 47. The spring urges the valve into the closed position as shown.

A fluid circulating cavity 46 is provided in the cylinder head 611. The cavity 46 surrounds the upper part of the valve stem, and the pipe 24 leads into and out of the cavity.

When the valve is opened fluid within cavity 46flows to the cylinder via metering channels 75 in the surface of cylindrical member 48. The cavity 46 is in communication via a passage 64 with an annular groove 63 in the bore 76. As the valve member is raised thechannels 75 are exposed in the valve chamber 411, and fluid flows into the chamber from the channels. The higher the valve member is raised, the more the channels are exposed, and the more fluid can flow into the chamber 41. The metering channels prevent excessive fluid flow at low engine speeds.

The cylinder exhausts by the known uniflow method, the exhaust (not shown) being uncovered by the piston at the end of each stroke. Any unexhausted steam in the cylinder is compressed into the expansion chamber 43 by the return stroke of the piston.

Alternatively the exhaust from the cylinder could be fed to other cylinders for further exapansion.

Insulating packing 62 is provided between the cylinder head 61 and the cylinder 40, and the heat flow between the abutting faces of the head 61 and the cylinder 40 can be varied by adjusting this packing.

The valve operating gear will be described below.

The valves in the chambers 15, 16, 17 are similar to that shown in FIG. 4 and are operable to direct hot fluid from the heater into their associated cylinders. If the valves are closed, fluid from the heater will by-pass the valves, and may be recirculated by pump 18, via pipe 28. The plant operates as follows:

Under normal running conditions, fluid passes to the valves from the heater at a pressure and temperature close to the critical pressure and temperature for steam and water; it is then admitted through the valves to the cylinders, the admission being timed, and the pressure in the cylinders being adjusted, so that the hot fluid flashes into steam on entering the cylinders.

The engine is started from cold with the valves in the chambers 15, 16, 17 closed so that fluid flows past the valves to pump 18, and not to the cylinders (see FIG. 4). The pump supplies water to the heater, where it is heated by the burner 9, flows through the chambers l5, 16 17, and is pumped back to the hottest coil element 29. Thus the hot fluid initially flows past the valves around a ring circuit as the temperature rises, the circuit comprising coil element 29, pipe 28 and pump 18. The arrangement may be such that pump 18 automatically comes into action when the burner 9 is switched on. The water supply means 11, governed by the pressure sensitive control means 21, adjusts the water input accordingly. The fluid is passed around this circuit until the temperatures of the valves and valve chambers have reached the normal operating level. If fluid were passed into the cylinders when the valves were too cold, the fluid would either not turn to steam, or would rapidly recondense to water.

Once normal operating conditions have been reached, a proportion of fluid is admitted to the cylinders where is flashes to steam and drives the pistons. The valves in the chambers 15, 16, 17 are operable to vary the proportion of fluid passing into the cylinders as previously described. Control means 11 adjusts water input according to the demands of the system, and the output of burner 9 is adjusted by control means 19. The control means 19 are responsive to the temperature of the water issuing from the hottest coil element of the heater.

Although the cylinders shown in FIG. 1 are arranged with the valves at the upper end of the cylinders, it is advantageous to have the valves at the lower end of the cylinders as shown in FIG. 4. The temperature of each valve chamber will be higher than the temperature of the associated cylinder, and any steam which condenses to water in the cylinder will flow down the cylinder into the valve chamber, where it will be reevaporated by the higher temperature.

The valve stem of each valve has, as shown in FIG. 4, a shoe 56 mounted on the foot thereof. The shoe 56 rests on one arm of a rocker 49. The rocker is pivoted at 50 to a bracket 80 slidably mounted on a rigid guide rod 51. The rocker is actuated by a rotatable cam 54 to control the opening and closing movements of the valve. If desired the rocker could be connected to the valve stem by push rod.

The rocker 49 may be moved to the left and right of FIG. 4 by an arm 52 connected to the rocker pivot point, and a crank 53 connected to the arm 52. Movement of the rocker to left or right varies the positions of the shoe 56 and cam 54 with respect to the rocker, thereby varying the stroke of the valve member. As the rocker moves to the left of FIG. 4, the stroke of the valve member decreases, substantially reaching zero when the pivot is directly beneath the shoe 56. The arrangement is such that the entire valve gear comes to rest when the valve stroke reaches zero. The right hand rocker arm slopes downwardly at its end 55, and when the pivot 50 lies under shoe 56, the sloping end 55 lies under the cam 54 so that the cam ceases to rock the rocker.

Movement of the rocker to left or right varies the stroke of the valve, but does not vary the time for which it is open or closed, except in the zero stroke position.

The crank 53 controls the power output of the system through rod 52. If more power is required, the rocker is moved to the right so that more fluid is directed to the cylinders and less passes along pipe 28 to pump 18. In the no-power condition the pivot is positioned under the shoe 56 so that the valves remain closed.

FIG. 5 shows an alternative valve control arrangement, comprising a lever 60 pivoted at 57 to a plunger 58. The plunger, carrying the lever 60 with it, may be moved to the left and right of the Figure by a crank 59, to vary the stroke of the associated valve member.

In FIGS. 4 and 5 the main working surface of each rocker is shown as being flat. It may, however, be desirable to make the surfaces curved to vary the timing or to pivot the rocker directly onto a controlling crank, instead of connecting it to a crank by means such as arm 52 or plunger 58. The latter arrangement is shown in FIG. 6. Since the pivot point 77 performs arcuate movement, the rocker is provided with curved portions to engage the shoe and cam respectively. The sole of the shoe is curved accordingly. The curved portions compensate for the vertical component of movement of the pivot point 77.

The timing of a particular machine may be determined by the choice of an appropriate rocker profile. For example, although the main working surface of the rocker in FIG. 5 is flat, the left hand end of the rocker has a projection thereon. Although it is desirable for injection of fluid into a cylinder to take place over a very short interval of time and not to extend substantially into the stroke time of the piston, it may be necessary to increase the time for which the valves are open when starting an engine. When starting a three-cylinder or four-cylinder engine for example, torque must be exerted through a 120 crank and/or crank angle respectively. Such an increase in time when starting may be obtained by the projection. When starting the engine, the rocker is moved to the right so that cam 54 will engage the projecting follower surface 60. The action of the cam on the projection will increase the time for which the valve is open and/or the lift of the valve over that time.

In known coiled tube flash heaters where it is the practice to use throttle arrangements which can cause the rate of flow through the entire heater to vary, it has been found that the final hottest stretch of the heater is liable to develop local hot spots if the flow through it is suddenly reduced or stopped. These hot spots can cause swelling and possible bursting of the tubes.

In the arrangement according to the invention, however, flow through the last and hottest portion 29 is maintained substantially constant irrespective of power output. This reduces the risk of hot spots developing, and also serves to warm up the valves and housings before starting.

FIG. 2 shows an alternative form of heater giving improved fuel combustion. In the FIG. 1 heater, the combustion gases reach the coil fairly quickly, and are therefore cooled fairly soon after combustion has commenced. Such an arrangement can result in incomplete combustion.

In the FIG. 2 arrangement, the heater comprises two coil assemblies 32 arranged in a casing 33 with a burner 34. The assemblies extend vertically and the burner 34 is arranged between them substantially at their feet. The casing has two guards 35 and a deflector 36. The combustion gases from the burner travel almost the full height of the heater before they are divided by the deflector 36 and diverted downwardly through the two assemblies 32. Thus there is provided a reasonable combustion space above the burner, so that the gases are not cooled too soon after leaving the burner. Combustion can be considerably improved. Each coil 32 may be composed of coil elements similar in form to coil element 25, and the water supply may be arranged toenter the lowest coil element of one coil 32, then pass to the lowest element of the other coil 32, then zigzag back to the second lowest element of said one coil 32, then to the second lowest element of said other coil 32 and so on up to the topmost elements, passing to the valves from the top element of the said other coil 32. The return pipe 28 of the ring circuit is preferably connected to the beginning of the top element of the said other coil 32 so that fluid circulates through the said topelement, is being in factthe hottest element. 7

The pipes connecting the elements of each coil together are not shown in FIG. 2, but pass in front of, and behind, the burner, as viewed in the Figure.

'1 The deflector 36 may become incandescent and assist combustion.

The embodiment of FIG. 7 is similar to the embodimentof FIG. 1 except that a by-pass 70 is provided around the chambers 16, 17. The flow tothis bypass is controlled by an infinitely variable diverting valve 71 and-a non-return valve 72 is provided to preve'nt'flow to the chambers in the reverse direction.

With the valve gear of the invention applied to an internalcombus tionengine it may be possible to vary the valve timing according to the engine speed required to obtain satisfactory torquet'hroughout the entire speed range, more efficient running at low powers due to reducedvalve opening and higher fluid velocity, quieter running at low power due to the small valve movement,

and more complete fuel combustion at low power due to preservation of turbulence. More complete fuel combustion should reduce the quantity of poisonous fumes emitted by the engine. It may also be possible to provide for engine braking'by compression.

The pipes 26 which support the boiler elements in the FIG. 1 arrangement may be joined up to form a secondary pipe circuit. Water may be passed through this circuit for pre-heating purposes prior to being admitted to pump 20. a The invention is not restricted to the features of the ders, or a single cylinder, may be used.

The chambers l5, l6, 17 may be arranged in parallel instead of in series, the connection from the thermostatic control 19, and the start of pipe 28, being divided into three branches connected respectively to the three valves.

The member 48, instead of comprising an integral part of the valve head, may comprise a collar of heat resisting material, for example ceramic.

The metering member 48 is not however an essential feature of the invention. Its purpose is to serve as a protection against excessive fluid flow into the cylinder should the engine run at very slow speed with the con trol in the high power position.

The poppet valve head and metering device may be replaced by a tapered valve on the principle of a needle valve.

The invention is not restricted to the use of water as the motive agent. Other liquids could be used, particularly liquids having a lower boiling point than water.

I claim:

1. Power plant comprising a fluid heater with an inlet and an outlet for the fluid, at least one piston and cylinder combination formed in a cylinder block and having an associated inlet valve for admitting fluid to the cylinder, a cylinder head provided with a valve port for the inlet valve, a pressure chamber in the cylinder head through which chamber fluid passes to the cylinder means connecting the outlet of the fluid heater to the valve port in the cylinder head, and further means interconnecting the pressure chamber to the heater to direct heated fluid from the chamber back to the heater to provide a continuous circuit.

2. Power plant as claimed in claim 1 including a bypass around the chamber so that heated fluid can flow back to the heater without passing through the chamber, a diverter valve being provided upstream of the chamber to direct fluid either to the chamber or the bypass. I I

3. Power plant as claimed in claim 2 in which the diverter valve is arranged to operate gradually whereby the fluid may be directed to the by-pass-and the chamber in any desired proportion.

4. Power plant as claimed in claim 2 in which a nonreturn valve is provided downstream of the chamber to prevent fluid from the by-pass from entering the chamber.

5. Power plant as claimedin claim 1 in which the heater comprises a coiled tube, having heating means which may comprise a gas or liquid fuel burner arranged to heat the tube. p

6. Power plant as claimed in claim 5 in which a temperature sensitive'device is provided in the said continuous circuit to control the heating means automaticall 7. Power plant as claimed in claim 1 in which the cylinder head is heat insulated from the cylinder block, and the inlet valve is of the poppet type.

8. Power plant as claimed in claim 1 in which the cylinder is located above the cylinder head.

9. Power plant as claimed in claim 1 in which the piston is provided with a hollow crown closed by a domed cap, a space being provided between the crown and the cap.

10. Power plant as claimed in claim 9 in which the space is filled with heat insulating material.

11. Power plant as claimed in claim I in which the valve is provided with a cylindrical neck which cooperfuel burner to heat the tubes.

13. Power plant as claimed in claim 12 including baffles to direct the exhaust gases from the burner downwardly through each coiled tube assembly.

Claims

2. Power plant as claimed in claim 1 including a by-pass around the chamber so that heated fluid can flow back to the heater without passing through the chamber, a diverter valve being provided upstream of the chamber to direct fluid either to the chamber or the by-pass.

3. Power planT as claimed in claim 2 in which the diverter valve is arranged to operate gradually whereby the fluid may be directed to the by-pass and the chamber in any desired proportion.

4. Power plant as claimed in claim 2 in which a non-return valve is provided downstream of the chamber to prevent fluid from the by-pass from entering the chamber.

5. Power plant as claimed in claim 1 in which the heater comprises a coiled tube, having heating means which may comprise a gas or liquid fuel burner arranged to heat the tube.

6. Power plant as claimed in claim 5 in which a temperature sensitive device is provided in the said continuous circuit to control the heating means automatically.

7. Power plant as claimed in claim 1 in which the cylinder head is heat insulated from the cylinder block, and the inlet valve is of the poppet type.

11. Power plant as claimed in claim 7 in which the valve is provided with a cylindrical neck which cooperates with a guide bore in the cylinder head and metering grooves are found in either the neck or the bore.

12. Power plant as claimed in claim 1 in which the fluid heater comprises at least two coiled tube assemblies interconnected together and having a gas or liquid fuel burner to heat the tubes.