GB2122257A

GB2122257A - Valve operating mechanism for internal combustion and like-valved engines

Info

Publication number: GB2122257A
Application number: GB08315465A
Authority: GB
Inventors: Paul Julian Moloney
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-06-04
Filing date: 1983-06-06
Publication date: 1984-01-11
Also published as: GB8315465D0; GB2122257B

Abstract

A valve 12 is operated by a piezo- electric device 1 responsive to engine operating conditions. The device 1 may act hydraulically or pneumatically on a valve-actuating piston (26, Fig. 2) or operate a valve or valves controlling fluid flow to an actuating piston (Figs. 3 and 4). The device 1 may receive signals from a micro-processor (91, Fig. 5) with feed back from a valve movement sensor (93) <IMAGE>

Description

SPECIFICATION Valve operating mechanism for internal combustion and like-valved engines This invention relates to a valve operating mechanism for internal combustion and likevalved engines.

It has for some time been realized that the requirements for engine valve timing in an internal combustion engine are variable depending upon the speed of the engine when optimum operation is desired. Thus in the use of the usual mechanically operated valve system, operated by means of a camshaft, selection is dependent upon the maximum engine power at high speed operation, minimum exhaust emissions at low speed part-load operation, or on some form of compromise between the two.

Considerable research has been undertaken on this subject which have largely produced the conclusion that, ideally, full control over every parameter of valve movement is required; and these parameters need to be varied in response to the operating conditions of the engine at any particular time. As a result of this research, various modifications have been proposed for existing camshaft installations, and in different ways in dependence upon the particular objectives which have been considered in the particular research involved. Nevertheless, no modification has been found which is capable of providing a full optimum control of the valve operation over the whole of the operating conditions of the engine, and, as a result, any proposed system is effectively only a compromise.

The present invention seeks to provide a valve operating mechanism for an internal combustion, or like-valved engine in which the operating mechanism enables a substantially full control to be exercised over all parameters for each of the valves of the engine.

According to the invention, there is provided a valve operating mechanism for an internal combustion engine or like-valved engine comprising a piezo-electric control device arranged to control the operating movement of the engine valve in accordance with the extension of the control device and control means for controlling the electrical feed to the piezo-electric control device in accordance with parameters of the engine operation fed to it.

In a first form of the invention, the piezoelectric device is coupled to the engine valve through an amplifying mechanical linkage.

In a second form of the invention, the piezoelectric device is connected to the engine valve through a fluid linkage including a hydraulic or pneumatic piston and cylinder arrangement for directly driving the valve.

In a third form of the invention, the piezoelectric device is connected to operate a spool valve, the spool valve in turn being connected to a slave cylinder connected directly to the engine valve.

In a fourth form of the invention, the engine valve is directly connected to a double acting piston and cylinder arrangement, the piston and cylinder arrangement being controlled by piezoelectrically controlled valves in the feed to the piston and cylinder arrangement.

Control of the piezo-electric device is preferably carried out with a feedback loop control circuit, the control circuit being fed with instructions by a microprocessor with associated memory which in turn is fed by values representing engine operating parameters. Such parameters may include crankshaft position, engine speed, mixture information, and exhaust information.

The invention will now be described in greater detail, by way of example, which reference to the drawings, in which: Figure 1 is a diagrammatic view of a value operating mechanism in accordance with the invention, with mechanical linkage between the piezo-electric device, and the valve.

Figure 2 is a diagrammatic view of a valve operating mechanism in accordance with the invention, in which two piezo-electric devices act as fluid/gas pumps.

Figure 3 is a diagrammatic view of a valve operating mechanism in accordance with the invention, in which a piezo-electric device is connected to a spool valve to control a hydraulic system.

Figure 4 is a diagrammatic view of a valve operating mechanism in accordance with the invention, in which four piezo-electric devices are connected to four hydraulic valves to control a hydraulic system, the piezo-electrically controlled hydraulic valves being shown in more detail in figure 4a.

Figure 5 is a block circuit diagram showing a typical proposal for the circuitry of the control means for control of the piezo-electric devices as shown in Figures 1-4.

Referring firstly to Figure 1 , there is shown a mechanical version of the valve operating mechanism. In this figure, the piezo-electric device is indicated as 1 and comprises a stack of piezo-electric discs 2 to which a voltage can be applied by a means not shown. One end of the stack of discs 2 is fixedly mounted at 3 in a housing 4 while the other end of the stack is freely movable. At this end of the stack, there is provided, an operating pin 5 which engages an operating lever arm 6 pivoted at 7 and carried by a carrier 8 mounted on the engine block 9. This lever arm 6 is connected at 10 to the actuating rod 11 of the valve 12. As will be seen, the relatively small movement of the piezo-electric device 1 is converted by the lever arm 6 into a considerably larger movement for actuating the valve 12.

In this embodiment, the voltage supplied to the piezo-electric devices acts by direct mechanical linkage on the valve 12, and the valve 12 will move thus in accordance with the voltage supply to the piezo-electric device 1. While in this embodiment no motion sensor has been provided for clarity, in order to enable operation with a feedback loop, a suitable sensor would be mounted to sense the movement of the valve.

Figure 2 shows a second form of the invention, where two piezo-electric devices, 13 and 14, generate and control the pressure of the fluid/gas, and hence control the movement of the valve 1 5 of an internal combustion engine. The two piezoelectric devices suitably comprise a number of piezo-electric discs, 16 and1 7, to which a voltage can be applied by a means not shown. One end of the stack of discs 16, 1 7 is fixedly mounted at 18, 19 in a housing 20, 21, while the other ends of the stacks are freely movable.At these ends of the stacks, there are connections 22, 23, which lead to a control ram 24, for actuating the valve 1 5. This ram comprises a cylinder 25 in which lie the piston 26 carried by a rod 27 which is suitably an extension of the rod 28 of the valve 1 5.

Connections 29, 30, are provided which are connected to the connections 22, 23, respectively, and provide for the feed or exhaust of fluid/gas from either side of the piston 26. The end of the rod 27 is suitably provided with a motion sensor, indicated schematically in the variable resistor 31. The system can be closed in that the same fluid/gas is used repeatedly, and connections 32, 33 are not needed, or, alternatively, connections 32, 33 can lead to connections 34, 35 through which extra fluid/gas can be supplied from the reservoir 36 under the control of the one-way valves 37, 38. These oneway valves could be controlled electrically or mechanically, by a means not shown.

In operation, voltages are applied to the stacks of piezo-electric discs 1 6, 1 7, (the magnitude and form of the voltage depending upon the required parameters of valve movement of the valve 1 5).

This voltage can be converted into an expanding longitudinal movement of one or more 'strokes' so as to feed fluid/gas under pressure to one side of the control ram 24. Alternatively, the voltage can be converted to a contracting longitudinal movement of one or more 'strokes' so as to control the flow of fluid/gas being exhausted from the control ram 24. Thus the actuating piston 26 will be moved longitudinally in the cylinder 25 in response to the voltages applied to the piezoelectric devices 13 and 14, and will open and close the valve in a controlled way. Feedback of the movement carried out is provided by the movement sensing device 31, and this information is fed back to control apparatus, as will be seen hereafter, in order to provide a control loop for control of the piezo-electric devices 1 3 and 14.

In some circumstances, particularly in this embodiment and those shown in figures 3 and 4, it may be desirable to provide a damper for the operation of the engine valve. This could take the form of a piston and dashpot connected to the end of the valve operating rod, suitably at the position indicated for the motion sensor. The motion sensor could then be suitably relocated.

Figure 3 shows a hydraulic control system actuated by a piezo-electric device 39, for controlling the valve, 40, of an internal combustion engine. For control of the engine, each individual valve would be controlled by an individual arrangement as shown in the drawing.

Thus, with a four cylinder engine, eight units would be necessary.

The piezo-electric device suitably comprises a number of piezo-electric discs 41, arranged in a stack and secured against any motion at one end, at any suitable stationary part, indicated in this case diagrammatically at 42. The other end of the stack of discs, 41, is in engagement with the spool 43, of a hydraulic spool valve 44. This valve consists of a casing 45 having two spool elements, 46 and 47, running in a bore 48 in the casing. A feed of hydraulic fluid under pressure is indicated at 49, and two return passages are indicated at 50 and 51. Also provided are connections 52 and 53 which lead to a control ram 54, for actuating the valve 40. This ram comprises a cylinder 55 in which lie the piston, 56 carried by a rod 57 which is suitably an extension of the rod 58 of the valve 40.

Connections 59 and 60 are provided, which are connected to the connections 52 and 53, respectively, and provide for the feed or exhaust of hydraulic fluid from either side of the piston 56.

The end of the rod 57 is suitably provided with a motion sensor, indicated schematically in the variable resistor 61. Note, that, although not shown, in practice, there is very likely to be either hydraulic or mechanical amplification of the movable end of the stack 41, resulting in a larger movement of the spool 43.

In operation of the device, a voltage is applied to the stack of piezo-electric discs 41, (the voltage depending upon the required position of the valve 40). This voltage is converted in the piezo-electric device 39 into a longitudinal movement, which is possibly amplified hydraulically or mechanically, (by a means not shown), and transmitted to the rod 43 of the spool valve 44, and controls input and output of hydraulic fluid to and from the cylinder 55, which carries the actuating piston 56. Thus the actuating piston 56 will be moved longitudinally in the cylinder in response to the voltage supplied to the piezo-electric device 39, and will open and close the valve as a result. Feedback of the movement carried out is provided by the movement sensing device 61, and this information is fed back to control apparatus, as will be seen hereafter, in order to provide a control loop for control of the piezo-electric device.

If the stack of discs 41 is not connected directly to the spool valve, but is connected hydraulically through amplification means, then the spool valve 44 may be provided with a return spring or may be controlled in each direction by a separate piezo-electric device.

Figure 4 shows a hydraulic control system actuated by four piezo-electric valves 62,...65, for controlling the hydraulic ram 66 which, by means of a connection 67, is connected to an internal combustion engine valve, (not shown).

For control of the engine, each individual valve would be controlled by an individual arrangement as shown in the drawing. Thus with a four cylinder engine, sixteen piezo-electric valves would be necessary.

The piezo-electric valves 62,...65, are shown in more detail at 68, in figure 4A. Each piezoelectric valve suitably comprises a number of piezo-electric discs 69, arranged in a stack, and secured against any motion at one end, at any suitable stationary part, indicated in this case diagrammatically at 70. The other end of the stack of discs 69, has its longitudinal motion amplified to move the disc 71, This motion amplification can be hydraulic or mechanical, but in this case is hydraulic via the fluid-filled chamber 72, and the movable piston 73, directly connected to the disc 71. The piezo-electric valve is normally held closed to fluid flow due to the spring 74 holding the disc 71 across the fluid orifices 75, 76, and hence preventing the flow of pressurized fluid.The spring 74 could however, be replaced by a second stack of piezo-electric discs.

A feed of hydraulic fluid under pressure is indicated at 77, 78, and two exhaust passages are indicated at 79 and 80. As can be seen, the two pairs of piezo-electric valves 62, 63 and 64, 65, are connected together at 81 and 82 respectively, which lead to two connections at 83 and 84, respectively. Connections 85 and 86, which are connected to connections 83 and 84 respectively, lead to a control ram 66 for actuating the internal combustion engine valve, which would be connected at 67. This ram 66 comprises a cylinder 87 in which lies the piston 88 carried by a rod 89 which is suitably an extension of the valve via connection 67. The end of the rod 89 is suitably provided with a motion sensor, indicated schematically as the variable resistor 90.

In operation of the device, a voltage is applied to the stack of piezo-electric discs 69 of some or all of the piezo-electric valves 62,...65, depending upon the parameters of motion of the internal combustion engine valve. This voltage is converted in the piezo-electric valve 62,...65 into a longitudinal movement, which is amplified hydraulically or mechanically, and hence uncovering the respective fluid orifices, shown in detail as 75, 76, and allowing pressurized fluid to flow to or from the control ram 66. Thus, the actuating piston 88 will be moved longitudinally in the cylinder in response to the voltages supplied to the piezo-electric valves 62,65, and will open and close the internal combustion engine valve via connection 67, as a result.

Feedback of the movement carried out is provided by the movement sensing device 90, and this information is fed back to the control apparatus, as will be seen hereafter, in order to provide a control loop for control of the piezo-electric valves.

Figure 5 is a block diagram of a suitable electronic control arrangement for operating the valves of an internal combustion engine, and provide for control of the piezo-electric devices as shown in Figures 1-4. In the arrangement of Figure 5, all the valves of an internal combustion engine are to be controlled by a single microprocessor and it's associated memory indicated at 91. In this figure, two groups of piezo-electric control devices are shown, indicated 92 and 92n, each group having one, (see Figure 1 8 3), two, (see Figure 2), or four (see Figure 4) piezo-electric devices associated with one motion sensing transducer, 93 and 93n, which feeds information into a piezo-electric feedback loop control circuit, 94 and 94n.

The loop control circuit 94 and 94n provides a single to a high-voltage interface, 95, 95n, which feeds it's associated group of piezo-electric devices, 92, 92n. This part of the circuit provides for a loop control system so that the movement transmitted by the piezo-electric device(s) to the valve is sensed and any deviation from the correct movement is corrected by means of the control circuit. In addition to this loop, instructions are also fed into the piezo-electric feed-back loop control circuit 94, 94n, by way of a data bus 96, which transmits instructions from the microprocessor and it's associated memory 91, to the control circuit. The microprocessor unit is fed with the necessary input data providing information as to the operational state of the engine.In the particular example shown, this information is provided at two inputs 97 and 98.

The input 97 is provided with a value indicating the crankshaft position, which may be detected by an optical or magnetic sensor. The input 98 is provided with values representing the engine load, and can be determined by an optical or magnetic sensor on a roadbearing wheel. Other information which can be included in the information presented to the microprocessor include engine speed, mixture, inlet conditons, and exhaust conditions.

The microprocessor is programmed to convert the information which is provided by it's inputs, 97 and 98 into instructions which indicate the optimal operation of the valve in question. These instructions modify the loop control circuit of the individual piezo-electric devices, 92 and 92n, so that optimum operation of the valves results. Thus the processor output data may represent timing, lift position and velocity profile for the operation of the associated valves.

Additional functions of the microprocessor can control the valve to provide a number of different effects. Firstly, admitted fuel-air mixture could be increased so as to make starting of the engine easier. Secondly, the engine could be used as a brake by causing the inlet valves to remain shut during intake strokes of the engine, and in this way cause an increase in deceleration of the vehicle to which it is connected. Thirdly, the lift of the inlet valve can be varied in such a fashion as to increase the pressure drop at the intake port. In this way, the velocity in Reynolds Number of the incoming mixture can be increased. Thus, the thermal efficiency of the engine can be increased, and it is possible to use very lean fuel-air ratios where there is only a part-load. It is also possible to dispense with, entirely, the carburettor butterfly, and rely entirely on valve control.This piezo-electric valve operating system can also easily cope with the extra demands of a turbocharger-supercharger installation; and in the hydraulic mode of the system, can provide valuable cooling to help cope with the increased heat generated.

Considering the construction of the piezoelectric stack itself, a typical piezo-electric material which would be suitable, is that known as PXE5 manufactured by Phillips, which provides an extension of 616x10-12 meters/volt. If a construction of 1 to 200 discs were used, each disc say 10 mm diameter, and over 5 mm thick, adequate, operation will be provided for the hydraulic systems outlined in Figures 2, 3, 4. For the mechanical arrangement such as shown in Figure 1, an even more responsive piezo-electric device would be needed, to obviate the necessity having an over large mechanical ratio.

In a typical situation, an operating voltage of between 500 and 2000 volts could be used. The current supply into the piezo-electric device would be of the order of milliamps, the power needed for driving the piezo-electric devices of an eight cylinder engine for example, would be very approximately the order of 1 H.P.

It will be appreciated that various modifications may be made to the above described embodiments without departing from the scope of the invention. For example, the loop control circuit could be omitted, only direct control of the piezo-electric device being provided. The hydraulic control could be replaced by a simple pneumatic control. Instead of providing a double-acting ram for the actual operation of the valve, this could be replaced by a single-acting ram with a return spring. Where the hydraulic control is used, the hydraulic control apparatus could all be housed together at a position spaced from the actuating cylinders of the valves, so that in this way a single control function limit is formed. In some circumstances, a single spool valve could be used to control a number of the valves which were required to operate in sequence and without overlap. In such a case, sleeve valves would be provided for switching from valve to valve.

From the above described embodiment, it will be seen that there is provided a valve operating mechanism which, with sufficient control functions, can control the operation of the valves of an internal combustion engine in respect of all their parameters of movement.

Claims

1. A valve operating mechanism for an internal combustion engine or like valved engine comprising a piezo-electric control device arranged to control the operating movement of the engine valve in accordance with the extension of the control device and control means for controlling the electrical feed to the piezo-electric control device in accordance with parameters of the engine operation fed to it.

2. A mechanism as claimed in claim 1 , wherein the piezo-electric device is coupled to the engine valve through an amplifying mechanical linkage.

3. A mechanism as claimed in claim 2, wherein the linkage comprises a lever arm pivoted at one end and acting on the engine valve at the other end, the piezo-electric device having an operating means engageable with the lever arm close to its pivot.

4. A mechanism as claimed in claim 1, wherein the piezo-electric device is connected to the engine valve through a fluid linkage including an hydraulic or pneumatic piston and cylinder arrangement for directly driving the valve.

5. A mechanism as claimed in any one of claims 1 to 4, wherein the engine valve is provided with a return spring.

6. A mechanism as claimed in any one of claims 1 to 4, wherein two piezo-electric devices are provided, one for driving the engine valve in the opening direction and the other for driving the engine valve in the closing direction.

7. A mechanism as claimed in claim 1, wherein the piezo-electric device is connected to operate a spool valve, the spool valve in turn being connected to a slave cylinder connected directly to the engine valve.

8. A mechanism as claimed in claim 1 wherein the engine valve is directly connected to a double acting piston and cylinder arrangement, the piston and cylinder arrangement being controlled by piezo-electrically controlled valves in the feed to the piston and cylinder arrangement.

9. A mechanism as claimed in claim 8, wherein four piezo-electrically controlled valves are provided, two of the valves controlling inlet and outlet of fluid respectively on one side of the piston while the other two valves control the inlet and outlet of fluid respectively on the other side of the piston.

10. A mechanism as claimed in any one of claims 1 to 9, wherein the or each piezo-electric device comprises a stack of individual piezoelectric eiements.

11. A mechanism as claimed in any one of claims 1 to 10, wherein the engine valve is fitted with a motion sensor to provide feedback for control of the piezo-electric member.

12. A mechanism as claimed in any one of claims 1 to 11, wherein the control means includes a microprocessor to which data on engine operation are fed.

13. A mechanism as claimed in claim 12, wherein the microprocessor is fed with the crankshaft position and the engine load.

14. A valve operating mechanism for an internal combustion engine or like valved engine substantially as described herein with reference to the drawings.