IMPROVEMENTS IN COMPRESSED AIR STARTER

Abstract: A compressed air starter including pneumatically operating starting valves for diesel engines, whereby includes one main starting valve connected to the cylinder head of the engine and provided with a valve body, which co-operates with a valve seat in order to alternatively open and close an inlet opening for compressed air to one cylinder, whereby during the start up of the engine, starting air (compressed air) continuously is supplied to the main starting valve, said valve body including one servo piston, which is controlled by servo air from a supply of servo air, which servo air is acting on the servo piston during moments related to the working phase of the engine. The object of the invention is to simplify the pipe arrangement for the compressed air at a diesel engine with several cylinders where it is usually arranged a main distributor for distributing the servo or pilot air, which controls the starting valves. The invention consists of a magnetic valve (17), which is connected to the main starting valve (8, 9, 10) and has a valve slide, which in one position (I-II) connects the supply (16) of servo air with a compression face of the servo valve (10), said servo valve hereby being activated to drive the valve body (8, 9) to the opening position and that, in a second position (II-III) of the valve slide, it controls the outlet from the supply (16) of servo air so that the servo piston drives the valve body (8, 9) to a closing position, said magnetic valve (17) being controlled by electric signals from a transmitter (20) controlled by the crank shaft or by an axis (22) rotating in accordance with the working phase of the engine.

Description: IMPROVEMENTS IN COMPRESSED AIR STARTER This invention relates to a compressed air starter including pneumati¬ cally operating starting valves for diesel engines, whereby includes one main starting valve connected to the cylinder head of the engine and provided with a valve body, which co-operates with a valve seat in order to alternatively open and close an inlet opening for compres¬ sed air to one cylinder, whereby during the start up of the engine, starting air (compressed air) continuously is supplied to the main starting valve, said valve body including one servo piston, which is controlled by servo air from a supply of servo air, which servo air is acting on the servo piston during moments related to the working phase of the engine. The object of the invention is to simplify the pipe arrangement for the compressed air at a diesel engine with several cylinders where it is usually arranged a main distributor for distributing the servo or pilot air, which controls the starting valves. Ordinary arrangements means that the piping must be doubled because of it is a need of sepa¬ rate pipes for the compressed air and separate pipes transporting the servo air. By this invention it is possible to reduce the length and the amount of pipes by that it only will be necessary with a short branch pipe for taking out the servo air from the main piping for the compressed air and this branch pipe is branched closely to the start¬ ing valve of each cylinder. It is also possible to achieve a more se¬ cure and more simple controlling of the starting procedure, which also applies for reversing the engine. The invention will also simpl fy the possibility of braking the engine with compressed air in the event that the engine must be stopped for reversed driving direction, which means that when the invention is used with a diesel engine for a ship the braking distance of the ship will be very much reduced. The invention is characterized by that a magnetic valve is connected to the main starting valve ancl has a valve slide, which in one position connects the supply of servo air with a compression face of the servo valve, said servo valve hereby being activated to drive the valve body to the opening and that, in a second position of the valve slide, it controls the outlet from the supply of servo air so that the servo piston drives the valve body to a closing position, said magnetic valve being control- O PI led by electris signals from a transmitter controlled by the crank shaft or by an axis rotating in accordance with the working phase of the engine. According to another embodiment of the invention the outlet from the supply of servo air is closed in said second position of the valve slide and the pressure face of the servo piston is hereby released of pressure. By this embodiment the piping is more simplified over the embodiment stated in claim 1. According to a third embodiment of the invention the supply of servo air is connected with the opposite side of the servo piston in said second position of the valve slide. The movement of the servo piston will hereby be controlled distinctly by the servo air instead of for instance the return stroke of the servo piston being carried out by means of a compression spring. According ' to still another embodiment of the invention the electric signals are produced by a capacitive transmitter placed in front of a sector formed plate, which is mounted on said axis, whereby the rela¬ tive position of said sector and its size of angle determines the moment of generation of the signal and its length (duration). The signals in this way will give a very reliable function with great possi bilities to so adapt the servo air that it acts on the servo piston in the precise moment and with a length of time which is exact long enough The relevant parameters are the size of the sector and also its rota¬ ting time in relation to the crank shaft. The relative position of the plate may easily be adjusted and moreover it is possible to construct the sector formed plate so that its angle may be varied or adjusted. Components of these kinds are very reliable in their operation and can stand vibrations and shocks. In the case of several cylinders, which is most common, there is one capacitive transmitter for each magnet valve. Alternatively, one single transmitter may be used, which is connected to each one of the magne¬ tic valves via an electric distributor, which means that it is only necessary to arrange on.capacitive transmitter for each engine. An embodiment of the invention will now be described with reference to the enclosed drawings. Fig. 1 is thereby a section of a part of a cylinder head in which there is installed a main starting valve of known type. Fig. 2 is a partly diagramatically cross-section of a starting valve including a servo piston, whereby the embodiment is mounted on the valve house of the starting valve. The impulse transmitter and the piping is shown diagramatically. With reference to Fig. 1 there is shown a cylinder head 1 of a usual diesel engine. A main starting valve generally designated with 2 is placed in the cylinder head. The main starting valve is of a known type but shall be described shortly. It includes a sleeve 3, which is inser¬ ted in a hole through the cylinder head 1 and with close fitting to the inner. surface of the hole, for instance by jointing rings 4. The sleeve 3 has also a closed fitting in a hole 5, which goes into the top of the cylinder. Starting air under high pressure is inserted through a channel 6 and an inlet 7 into the sleeve. Within the sleeve there is a valve bo¬ dy including a shaft 8 and a valve disc 9. The compressed air, which enters the sleeve 3, can pass out through the opening 5 when the valve disc 9 opens the corresponding opening in the under end of the sleeve. The shaft 8 is in the upper end connected to a servo piston 10, which is forced upwards by a compression spring 11. A space within the sleeve is above the servo piston 10 and the servo air can be inserted to that space through a channel 12. The upper end of the sleeve 3 is covered by a cap 13. The operation of the main starting valve is as follows: Starting air or compressed air is supplied continuously during the starting procedure of the engine through , the channel 6 but the valve body will not be affected to move in any direction because the starting valve is balan- ced by equal areas of the servo pistons 10 and the valve disc 9. Further, the compression spring 11 acts upwards preventing the valve disc 9 from being moved to opening position. When servo air is supplied via the channel 12 to the upper side of the servo piston, the balancing action will be ceased and the valve shaft 8 with the valve disc 9 will be quickly moved downwards, so that the main starting valve is open and starting air or compressed air may pass from channel 6 through inlet 7 and- through the inner space of the sleeve 3 and over the val disc 9 and through the opening 5 and into the upper end of the cyli The engine piston (not shown) will hereby be pressed downwards from initial top position whereby the engine will start running. An embodiment of the invention will now be described with reference Fig. 2. Fig. 2 shows, at right side, a section through a part of a c linder head with its main starting valve, whereby 8 designated the s of the valve and 9 designates its valve disc and 10 designates the s piston. There are also the inlet channel 6 for the starting air for ressed air and an inlet channel 12 for the servo air. The starting a is supplied to channel 6 from a supply pipe 14, which has a branch p 15 leading to the channel 16. From the supply pipe 14 there is a sec branch pipe 16, from which the servo air is passed in order to contr the servo piston 10 and the supply is carried out via the channel 12 The control of supply of servo air is carried out by a magnet valve, which is generally designated with 17. The magnet valve has a slide (not shown), which has two end positions so that in one of these end positions the two ports designated with the arrows I and II are conn ted, whereby the supply of servo air to channel 12 is carried out, a that in the second end position, when, the ports designated with the arrows II and III are connected, channel 12 is vented and the port a the arrow I is closed. The slide of the magnet valve 17 " is controlle according to the working phase of the cylinder to which " the main sta ting valve 8, 9 and 10 belongs. The control of the magnet valve 17 i carried .out by electric pulses, which are supplied by a.circuit, whi includes the leads 18 and 19. The pulses are supplied by a capacitive transmitter 20, which is pla in front of a sector formed plate 21, which is fastened on a shaft 2 which is at right angle to the plate and which is rotating in time t the rotation of the crank shaft. The capacitive.transmitter is mount excentric in relation to the axis 22 and thus also- excentric in rela tion to the centre of rotation of the sector formed plate 21. The fo of the sector is shown in Fig. 2 by the section A-A. The sector form plate 21 is mounted in a ring and which is suspended " by a stubb axis via spokes (not shown). The ring 31 has a peripheric groove, in which the sector formed plate 21 is mounted. The s ' tubb axis 32 and thus the rimg 31 is rotated by the axis 22. In order to drive the plate 21 in the rotational movement of the ring, a shoulder 33 is placed in the groove of the ring. The position of the shoulder 33 thus determines the rela¬ tive position of the sector formed plate in relation to the angular position of the crank shaft and in relation to the position of the capa¬ citive transmitter 20. The capacitive transmitter produces an electric pulse when the sector formed plate is in front of the transmitter but as soon as the plate has passed, the electric pulse or the signal will be ceased. The supplied electric signal arrives to the magnetic valve 17, which adjusts the slide so that the ports at the arrows I and II are connected and thus servo air is supplied from the branch pipe 16 via.channel 12 to the upper side of the servo piston 10. Hereby the valve disc 9 is opened and starting air is inserted in to the cylinder of the engine. When the piston of said cylinder has reached its bottom dead centre, the sector formed plate 21 will pass over the transmitter 20, whereby the electric signal accordingly is ceased. This means that the magnetic valve 17 wi]] hold a different position meaning that its slide is closing the connection between the ports at the arrows I and II and will open a connection between the ports at the arrows II and III, which means that the pressure is released above the servo piston 10, whereby the main starting valve is closed and the supply of starting air is cut off. When the engine shall be.started in reversed direction (backward mo¬ tion) the magnet valve 17 shall open for supply of servo air at another angular position of the crank shaft (known per se). The correct position of the sector formed plate 21 in relation to the angular position of the crank shaft is adjusted by that a second shoulder 39 is mounted on the other side of the sector in the groove of the ring 31. This shoulder 39 :t. will drive the plate during the reversed motion, so that the electric signal is produced during a different moment than that which applies to forward motion of the engine. When the engine has several cylinders, the same amount of transmitters 20 are mounted in front of the rotation area of the sector formed plate 21. Alternatively, one transmitter may be used, whereby, however, the number of revolutions of the sector formed plate must be higher and j. relation to the number of cylinders. It is also to take into considera tion whether the engine is a two-stroke cycle engine or a four-stroke cycle engine. When, thus, one transmitter is used for several cylinder a distributor must be used for distribution of the electric signals fr the only transmitter and such a distributor is known per se and used w the usual Otto-cycle machines. As can be seen from the above description, one magnet valve is mounted to each main starting valve and hereby only a short pipe 16 will be necessary to supply servo air to the servo valve and control it. It, thus, will be unnecessary to have two different pipings along for the air as is taught by the known art. In Fig. 2 there is shown only sche¬ matically a magnet valve, but it is of known type and it shall be note that there are many different types which can be used. The specific construction of the magnet valve may be dependent on the type of main starting valve to be used and thereby the operation and the form of the servo piston 10. Thus, in the shown embodiment, one side of the servo piston is pressurized when the servo piston shall be moved in on direction and the pressure will be released from this side of the pis¬ ton when the piston is performing its return stroke. However, it is possible, in an alternative embodiment, that one side of the servo piston is pressurized for carrying out the motion in one direction whereas the other side of the piston is pressurized for performing the return stroke of the servo piston. If so, a different type of slide of the magnetic valve 17 must be used than the one schematically shown an described above. Further on it is possible within the scope of the invention to use an alternative form of signal to be supplied to the magnet valve. Thus, it is. possible to use an impressed voltage on the magnet valve to keep it in one of the two positions, while the magnet valve will have its second position when the ypltage is null. This control may be carried out by switches of known type which are controlled to operate according to the working phase of the engine. Also, it is possible to control the. signal by a photo-cell. When starting up for reversed motion of the engine, it is possible to alter the signals by that the order between the signal transmitter and the cylinders are changed and this can be accomplished by an electric switching means between the transmitters and the magnet valve. This means that a signal from one transmitter will reach the magnet valve of for instance a fifth cylinder instead of the magnet valve of the first cylinder.

Claims: CLAIMS: 1. Improvements in compressed air starter for diesel engines includi a main starting valve connected to a cylinder head and including a val body, which co-operates with a valve seat for opening and closing of a inlet for compressed air to the cylinder of the engine, whereby compres sed air during the starting operation continuously is supplied to the main starting valve and whereby the valve body includes a servo piston, which is controlled by servo air from a supply, which servo air is acti on the servo piston during moments which are related to the working pha se of the engine, c h a r a c t e r i z e d by that a magnet valve is connected to the main starting valve and has a valve slide, which in one position connects the supply of servo air with a pressure side of the servo piston, so that it can drive the valve body to an opening position and which valve slide in a second position controls the supply of servo air so that the servo piston drives the valve body to a closin position, said magnet valve being controlled by electric signals from a transmitter controlled by the crank shaft or a shaft rotating synchro¬ nously with the crank shaft. 2. Improvement according to claim 1, c h a r a c t e r i z e d by that the supply of servo air is closed and that the pressure side of the servo piston is vented in said second position of the valve slide. 3. Improvement according to claim 1, c h a r a c t e r i z e d by that in said second position of the valve slide the supply of servo air is connected with the opposite side of the servo piston. r 4. Improvement according to claim 1, c h a r a c t e r i z e d by that the electric signals are produced by a capacitive transmitter, which is mounted in front of a sector formed plate, which is mounted on said axis and rotates thereby, whereby the angular position of the sector and the size of the angle determines the moment of generation of the signal and its length. 5. Improvement according to claim 4, whereby the engine includes se¬ veral cylinders, c h a r a c t e r i z e d by that one capacitive transmitter is incorporated with each one of the magnet valves and that the transmitters are mounted along a circular path in front of the IJUREA O PI rotating plane of the sector formed plate. 6. Improvement according to claim 4, whereby the engine has several cylinders, c h a r a c t e r i z e d by that the capacitive trans¬ mitter is connected with a magnet valve for each main start valve via an electric distributor. 7. Improvement according to claim 4, c h a r a c t e r i z e d by that the sector formed plate is mounted freely rotating in a ring in its plane and concentric with the ring, whereby the ring is fastened on said rotating axis and has at least one shoulder, which drives the sector formed plate in at least one direction of rotation. 8. Improvement according to claim 7, c h a r a c t e r i z e d by that the ring has a second shoulder, which drives the sector formed plate in an opposite direction of rotation and which shoulder is so positioned, that the sector formed plate will have a position in relation to the angular position of the crank shaft, which position corresponds to reversed motion of the engine. 9. Improvement according to claim 1, c h a r a c t e r i z e d by that the electric signal is an impressed voltage, which is changed in time and length by a switching menas, which is controlled in relation to the working phase of the crank shaft. IJUREA^ OMPI

Inventors: HELLEMAA H, SAMUEL O
Applicants: HELLEMAA H, NORDSTJERNAN REDERI AB, SAMUEL O
Application year: 1979
Main classification: F02N9
IPC codes: F02B3, F02N9