This invention relates to fluid-electric actuated valves for reciprocating piston engines such as internal combustion (I.C.) engine valves that are opened and closed by means of an electric current in combination with pressure applied by a fluid that may either be vapor such as steam a gas such as compressed air or a liquid such as hydraulic fluid.
The electronic operation of reciprocating piston engine valves such as internal combustion engine valves offers the potential of advancing or retarding valve actuation (phase control) as well as the possibility of electronically tailoring the valve opening and closing time within each cycle of operation by means of the engine control unit computer to reach performance goals such as reduced fuel consumption that are unobtainable with variable camshaft phasing currently used for example in cars and trucks.
Several electrical and hydraulic systems have been proposed but none have been commercially successful with regard to cost and performance. Fully electric designs exemplified by U.S. Pat. Nos. 4,829,947; 6,220,210 and 6,237,550 have been proposed but have not been adapted for wide sale commercial use. The same is true of electrohydraulic internal combustion valve actuators such as those described in U.S. Pat. Nos. 5,509,637; 4,009,695; 6,604,497; 4,878,464; 4,974,495; 6,089,197; 7,063,054 or 7,347,171. Steam engine valves have been actuated by an electromagnet and by steam, e.g., U.S. Pat. No. 8,448,440 but steam is not available in cars or trucks and there is no internal combustion (I.C.) valve nor any recognition in the patent of applicability or benefit concerning internal combustion engines.
Existing I.C. valve actuator systems ordinarily require a heavy duty engine valve closing spring for applying a force of typically about 300 lb.-1000 lb. together with one or more solenoid operated hydraulic valves each connected by ducts to a hydraulic actuator piston which is, in turn, connected to the engine intake or exhaust valve. Besides being complicated in construction, the heavy valve seating springs can reduce valve cycling speed and contribute to valve actuator power requirements which are a function of the product of spring stiffness and the square of the valve lift.
In view of these and other deficiencies found in previous reciprocating engines such as internal combustion engine valves and actuators such as those proposed for use in vehicles, e.g., cars and trucks, it is a general object of the present invention to find a mechanically simplified yet more effective way to employ electric control of a fluid (gas such as air or a liquid) for regulating the opening and closing of internal combustion (I.C.) engine valves at different selected time intervals.
Another object is to be able to open and close I.C. valves at a significantly faster rate than is accomplished by the harmonic action of a camshaft.
Another object is to find a way to actuate I.C. valves using electronic triggering that is capable of operating the I.C. valves with variable phase control at a cycling rate of at least 60 Hz (7200 rpm for a four-stroke engine).
Still another object is to provide a fluid actuated I.C. valve in which fluid at supply pressure applies a selected I.C. opening force followed by a closing force great enough to achieve an abrupt closing action.
Still another object is to provide electromagnetic valve actuation with a significant valve lift, e.g., 10 mm or ⅜ inch, yet provide a magnetic traction force to initiate valve motion that is not significantly diminished by being applied in an area of reduced magnetic flux density.
Another object is to provide I.C. engine in which I.C. valve closing motion is initiated electrically and is continued in the same direction by the application of fluid pressure
Another object is to begin closure of the I.C. valve electrically and to open the valve by the application of fluid pressure at the end of a separately determined time period.
Another object of the invention is to operate I.C. engine valves using a single signal, e.g., an electrical current sufficient to initiate timed valve closure in which the timed opening step that follows continues automatically without a need to either engage further mechanical elements or provide added electronic input.
Yet another object of the invention is to close each I.C. valve entirely or almost entirely by fluid pressure rather than by using a heavy valve spring of the kind commonly found in I.C. engines thereby eliminating the resistance of a typical valve spring, reducing valve work and achieving higher cycling rates.
These and other more detailed and specific object and advantages of the present invention will be better understood by reference to the following figures and detailed description which illustrate by way of example but a few of the various forms of the invention within the scope of the appended claims
All citations listed herein are incorporated herein by reference as fully and completely as if reproduced herein in their entirety and specifically indicated to be incorporated.
The present invention provides an actuator assembly for reciprocating piston engines such as internal combustion engines in which an electromagnet having an armature and a control valve having a valve piston or spool are all operatively associated with one another on a common valve stem that can transmit opening and closing motion to an internal combustion inlet or exhaust valve and yieldable biases the internal combustion valve to an open position. While having a simple mechanical construction the invention is able to eliminate the heavy closing spring commonly used on such inlet or exhaust valve while also eliminating cam shafts, push rods and rockers. In operation, the electromagnet armature when attracted by the electromagnet initiates movement of both the I.C. engine valve and fluid control valve by moving through a narrow air gap (typically less than 0.025 inch or 0.38 millimeter). After the control valve piston is thus moved slightly off its seat, pressurized fluid, e.g., air or hydraulic fluid is injected between the valve and its seat, instantly driving the spool the much greater distance required to seat the I.C. valve and continue to hold it closed for the rest of its cycle. An electronic control unit (ECU) controls the time the I.C. valve is allowed to remain closed. Fluid pressure is then balanced at both ends of the control valve piston (spool) which may have a different diameter at each end allowing an equal fluid pressure on the ends to drive the control valve spool in a reverse direction to open the I.C. valve. Both opening and closing events are controlled independently by the ECU thereby enabling the beginning, duration and end of the valve-open interval to each be changed separately as required to optimize engine operating conditions. Actuators according to the invention can also be used on other reciprocating piston engines such as steam engines.
The electromagnet 19 can be of various shapes such as rectangular or a donut-shape but preferably has a laminated E-shaped iron core as shown with poles as indicated and an electrical conductor winding 20. The electromagnet 19 has a downwardly opening pocket 19b to provide space for the stop 17 when the valves 14, 16 and stem 14a are elevated. Both the electromagnet 19 and the springs 19c and 19d can be held inside a housing 19e which is bolted onto cover 24 at the top of the actuator casing 11 with a gasket G between them to hermetically seal the electromagnet to the top of the cover 24. This prevents air leakage from the top of the actuator without the need for packing around the top of the stem 14a. An O-ring 20a seals the cover 24 to the casing 11.
Both the upper and lower sections of the control valve 16 are provided with compression rings R that seal the valve body and the surrounding bore. The lower edges of the bottom set of rings R can be chamfered to facilitate insertion. Alternatively, the casing 11 has a horizontal parting line (not shown) so that the rings can be more easily compressed as they are being inserted. The valve piston or spool 16 is sealingly and slidably mounted at its upper end within a sleeve 21 that is pressed into an upper bore 21a in the casing 11. The lower end of valve body 16 is slidably and sealingly mounted in a coaxial lower bore 26 of a smaller diameter in the casing 11. A partition P can be welded in place within the valve piston or spool 16 with a recess for spring 23. The larger ID of the sleeve 21 makes it possible for the same fluid supply pressure at both ends of spool 16 to create a much greater downward force on the valve body so as to overcome the upward force from below thereby opening the I.C. valve. The ratios of the large and small diameter at the ends of the control spool 16 are arranged such that an initial increase in fluid pressure on the larger diameter in control cavity 27 the instant the spool is raised together with the force of the spring 23 as installed does not exceed the fluid force at the opposing lower end of the control valve 16. In one prototype the large bore diameter was 2.25 inches and the lower bore was 2 inches.
Spool 16 is urged downwardly onto a tapered seat 16b by the compression spring 23 that can have a compressed force of about 20-30 lbs. The installed (minimum) force which can be in the range of 10-15 lbs. is arranged to exceed the efflux gas pressure on the head of the I.C. valve 14 during the exhaust stroke.
Inside the sleeve 21 within the casing 11 is a timing control cavity 27 above the valve spool 16 which when seated communicates via circumferentially distributed ports 21c in sleeve 21 through a counter bore 28 and an outlet duct 30 leading to a sump or sink at atmospheric pressure (not shown).
The lower bore 26 is surrounded by a counter bore 26a that communicates with a fluid supply or inlet duct 32 through which fluid either a gas such as air, steam or a hydraulic fluid is pumped at a selected pressure, e.g., 100-400 psi during operation. The air space within sleeve 21 below the top portion of the spool 16 is vented to atmosphere through duct 16f. The valve spool 16 has a downwardly and centrally tapered poppet valve surface 16a at its lower end which is yieldably biased by spring 23 in sealing engagement with the seat 16b while the I.C. valve 14 is fully open as shown in
In the last 0.030 inch downward movement of the spool 16 when the top ring R passes and then opens the ports 21c, momentum and spring 23 carries the spool onto seat 16b thereby removing all upward force on the spool. In the embodiment of
Just below the tapered poppet valve seat 16b is a valve chamber 40 within the casing 11 that communicates when valve spool 16 is off its seat 16b between the bore 26, the supply duct 32 and a metering duct 42. In the metering duct 42 is a metering needle valve 44 that is yieldably urged off of its seat 46 by a compression spring 48 to enable the flow rate of fluid from the supply duct 32 and valve chamber 40 to be regulated through duct 42 into the timing control cavity 27 above the valve body 16 for controlling the seating of spool 16 as will be described below.
The valve stem 14a is slidably mounted within a standard valve guide 14b which extends upwardly into a commercially available rubber valve seal 13. Above the seal 13, the valve stem 14a is sealed by means of a fiber reinforced compression packing 13a and two O-rings 13b. A lower portion of the valve stem 14a can be secured to on upper portion by screw threads 14d that are secured in place by means of a set screw 14c.
It is preferred that the cross-sectional area of the upper end of the spool 16 is somewhat larger than the area at the lower end of the spool, in this case for example, 2.25 inches diameter at the top and 2 inch diameter at the lower end of the spool 16. With this diameter ratio the force applied to the top of spool 16 due to compression at the moment the valve 16 is first raised to its uppermost will not exceed the force applied by supply pressure to the lower end of the spool 16. The pressure will then be able to rise in the timing chamber 27 responsive to the controlled flow rate through the valve 44 until a much greater down force and spring 23 slams the valve 16 to its seated position of
To correctly time the I.C. valve 14, the ECU 58 must have the time of its opening and closing.
Operation with Compressed Air or Steam
The operation of the apparatus for controlling I.C. valve timing when using compressed air or other vapor, gas as a working fluid will now be described. Before starting, the spring 23 holds valve spool 16 closed and I.C. valve open. A current pulse from the ECU 58 at the time selected energizes the electromagnet 19 raising the armature 12, first taking up tappet clearance to bring its upper surface into contact with the lower surface of the stop 17. The armature then rises through the air gap, typically about 0.010 to 0.025 inch until the armature is seated on the pole face A-B of the electromagnet 19 while imparting upward movement to the valve stein and both valve 14 and spool 16. Because the armature is little more than a microscopic distance from the electromagnet 19, it can be seen that the force applied by the electromagnet 19 can approach the maximum that its magnetic force field is capable of achieving, i.e., a force that is not significantly diminished by having been produced in an area of reduced magnetic flux density. This helps maximize both the magnetic traction force and cycling rates.
While the piston 16 is seated, there is no axial thrust applied to it regardless of the pressure of the compressed air supply in duct 32. However, as the valve spool 16 is lifted off its seat 16b slightly by the armature 18, compressed air or other fluid is injected past the valve seat 16b below the valve spool forcing the spool upwardly closing the I.C. engine valve 14 as well as closing the outlet vent ports 21c that lead through duct 30 to the sump. In this way the upward fluid pressure applied to the valve spool 16 from below makes it possible to eliminate the heavy spring commonly used in I.C. engines. As the valve 16 rises off its seat the valve stem 14a slides upwardly through the opening 18a in the armature and the stop 17 moves up into the pocket 19b.
With spool 16 off its seat, air flows past the control needle 44 through duct 42 into the control cavity 27. When the pressure above valve spool 16 exceeds the force of spring 23 and the upward force from below the valve, the spool 16 is propelled onto its seat 16b at the time established by the setting of needle 44 thereby opening the I.C. valve at the time selected by ECU 58. The larger ID on the top of the spool in the sleeve 21 makes it possible for the same fluid supply pressure at both ends of spool 16 to create a greater downward force on the valve body so as to greatly exceed the upward force from below thereby driving open the I.C. valve. The closer metering valve 44 is moved to its seat 46, the longer is the time interval required for the pressure in cavity 27 to exceed upward fluid pressure on valve 16. When metering valve 44 is opened more, the time interval is shortened.
Operation with Liquid Hydraulic Fluid
Operation is generally as described above. However, to prevent a relatively static fluid condition in the duet 42 past the control needle 44, a commercial hydraulic accumulator 60 preferably of the gas pressurized type having a sealed chamber 60a can be coupled to duct 42 between needle valve 44 and control chamber 27 through a port 61. During operation when magnet 19 raises the armature 18 causing pressurized hydraulic fluid to be injected below valve body, the I.C. valve 14 is almost instantly driven onto its seat 12a and the outlet ports 21c which lead to the sump at atmospheric pressure are closed. Pressurized hydraulic liquid then flowing past needle 44 in duct 24 charges the accumulator 60 to the supply pressure, at a rate regulated by setting of the control needle 44. When the rising pressure in accumulator 60 and timing control chamber 27 overcomes the hydraulic lifting force on valve body, the spool 16 is forced down against its seat 16b moving the I.C. valve 14 to its fully open position at the selected time. If the ECU 58 and the control rod 54 move each valve 44 closer to its seat 46, the timing of the opening of I.C. valve 14 is phased later in the cycle. When each valve 44 is raised further off its seat, each I.C. valve 14 is opened earlier in the cycle.
Refer now to
A test article comprising a laminated electromagnetic 19 and armature 18 measuring 2.5×3×1 inch with a stator winding of 40 turns and an armature air gap set at 0.010 inch when supplied with 12.4 amperes DC will develop an indicated traction force on the armature of about 150 lbs. When using a return spring 23 of 30 lbs., the net upward force on the armature therefore is 120 lbs.
When running at 7200 RPM, the duration of each cycle of two revolutions in a four-stroke engine would be 60 cycles per second or 16.7 ms. per cycle. A typical exhaust valve is open about 250/720 of each 16.7 ms. cycle or 5.8 ms. and closed for 10.9 ms.
A cycling test was conducted using a snubber type network circuit of known construction in which the test article having an air gap of 0.010 inch drew 12.4 amps at 60 hertz. Conditions were as follows during the test: Stator winding 0.049 ohms at an inductance of 0.003 heneries, sensing resistor 0.113 ohms at 1.4 volts and current measured at 12.4 amperes. An oscilloscope indicated the time period required to build up flux in the magnet was 3.5 ms.
The remaining time indicated to move the armature and the entire valve train weighing about 0.5 lb. up 0.375 inches by applying a pressure of 100 psi to control valve 16 having an OD at its lower end of 2 inches to a fully closed position is 1.7 ms. resulting in a total control valve opening time of 5.2 ms. (3.5+1.7 ms) out of the complete cycle lasting 16.7 ms. at 7200 RPM. During operation the closing of the I.C. valve can then be detected by the sensor 51 so that the ECU 58 has information to then advance or retard the actuation pulse to the electromagnet 19 such that closing of the I.C. valve occurs at the desired point in the cycle. When cycled at 120 Hz for over an hour, the total electromagnet energy loss was 15 watts which was within acceptable limits.
The terms “up”, “down”, “raise”, “lower” and the like are used relative to other parts of the device not to orientation relative to the earth.
Many variations of the invention within the scope of the foregoing specification will apparent to those skilled in the art once the principles described herein are read and understood.
The present application is a continuation-in-part of Ser. No. 13/532,853, filed Jun. 26, 2012, now U.S. Pat. No. 9,316,130, which is a continuation-in-part of application Ser. No. 12/959,025, filed Dec. 2, 2010, which in turn is a continuation-in-part of application Ser. No. 12/539,987, filed Aug. 12, 2009, which in turn is a continuation-in-part of application Ser. No. 12/492,773, filed Jun. 26, 2009 (now abandoned), a continuation-in-part of copending application Ser. No. 12/844,607, filed Jul. 27, 2010, a continuation-in-part of Ser. No. 12/387,113, filed Apr. 28, 2009 and Ser. No. 12/075,042, filed Mar. 7, 2008. The applicants also claim the benefit of the following provisional applications: 61/309,640, filed Mar. 2, 2010; and 61/320,959, filed Apr. 5, 2010; and 60/905,732, filed Mar. 7, 2007, all of which are incorporated herein by reference.
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Number | Date | Country | |
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Parent | 13532853 | Jun 2012 | US |
Child | 15055138 | US | |
Parent | 12959025 | Dec 2010 | US |
Child | 13532853 | US | |
Parent | 12844607 | Jul 2010 | US |
Child | 12959025 | US | |
Parent | 12539987 | Aug 2009 | US |
Child | 12959025 | US | |
Parent | 12492773 | Jun 2009 | US |
Child | 12539987 | US | |
Parent | 12387113 | Apr 2009 | US |
Child | 12492773 | US | |
Parent | 12075042 | Mar 2008 | US |
Child | 12387113 | US |