FUEL INJECTION APPARATUS

Abstract: Fuel is pumped and supplied to an injector (114, 208, 308, 408) which injects the fuel in the form of mist. The quantity of fuel injected from the nozzle is regulated by quantity control means. The control means is comprised of a control valve (152, 210, 310, 410), which is disposed on the injection hole (153, 238, 342, 426) of the injector for controlling the area of the injection hole. When the control valve has sufficient stroke to close the injection hole, the valve serves not only as a control valve, but also as a timing control valve. The movement or stroke of the control valve is accomplished by an actuator (126, 218, 338, 418) which is controlled by electrical control means, for example a microcomputer (122, 205, 305, 405), to enable a precise injection of fuel and an ideal combustion.

Description: The invention generally relates to fuel injection apparatus for an internal combustion engine and particularly, though not exclusively, to fuel injection apparatus for a compression ignition or Diesel engine. The conventional Diesel engine has a fuel injection pump to inject fuel into each of the cylinders. The fuel injection pump pumps the fuel and supplies it to a fuel injector which has an injecting nozzle. A timer is provided on a cam shaft of the fuel injection pump to control the timing of the fuel injection. The injection pump also requires a mechanical governor, which is connected to a control rack of the pump to regulate the quantity of fuel injected at one time, and thereby to ensure the supply of a suitable quantity of fuel to the engine in response to the condition thereof. Thus, the conventional fuel injection apparatus includes a fuel injection pump, a mechanical governor and a timer, which are all complex mechanical structures, thus making the fuel injection apparatus very expensive. Furthermore, these complex apparatus require highly skilled maintenance. Moreover, the conventional fuel injection apparatus is not suitable for electric control for example by a microcomputer. Additionally in using the conventional apparatus, it is very difficult to control the pattern of fuel injection, and more specifically it is very difficult to decrease the quantity of fuel at the initial period of the injection. Therefore the engine generates noises and the exhaust gas of the engine contains large quantities of nitrogen oxide. My Patent Specification EP-A-147026 discloses fuel injection apparatus for an engine comprising a fuel accumulator to hold fuel under pressure, a timing control valve to control flow of fuel from the accumulator to any injection nozzle, a quantity control valve to control the quantity of fuel injected by the injecting nozzle at any one time and electric control means to control the timing control valve and the quantity control valve in accordance with the speed of and load on the engine. USA-4 669 429 discloses an injector in which upward fullstroke of a nozzle needle is controlled. Such an injector is to be connected to a conventional injection pump and the injector is periodically supplied with pressurised fuel which displaces the needle upwardly against a spring to separate the needle from a valve seat so that the pressurised fuel can be injected through the injection aperture. US-A-4 462 368 discloses an injector with an injection aperture formed laterally on the periphery of the injector, a cylindrical quantity control valve, an actuator and electric control means. According to the invention there is provided fuel injection apparatus for an engine, wherein fuel under substantially constant pressure is continuously supplied to an injector to inject a mist of fuel, the injection apparatus comprising: an injection aperture formed substantially laterally on the periphery of the injector to inject fuel; a quantity control valve formed as a hollow cylinder to control the quantity of the fuel by regulating the effective area of the injection aperture; an actuator to displace the quantity control valve axially in the injector; and electric control means to control the actuator in response to speed of and load on the engine; characterized in that the actuator moves the quantity control valve in an axial stroke sufficient to close the injection aperture, thereby to operate the opening and closing of the injection aperture so that the quantity control valve serves as a timing control valve, and longitudinally extending slits or slots are provided in the wall of the cylindrical quantity control valve to allow deformation of the wall by the pressure of the fuel so as to give close contact with an edge or a valve seat of the injection aperture. Such fuel injection apparatus can eliminate a periodical fuel injection pump, a mechanical timer and a mechanical governor, need not require highly skilled maintenance thereof, can be completely electrically controlled and can reduce the quantity of fuel during the initial fuel injection period in order to decrease the engine noise and nitrogen oxide in the exhaust gas when the quantity control valve is controlled by the electric control means through the actuator so that the quantity control valve reduces the size of the injection aperture to accomplish a pilot injection at an initial stage of each injection cycle. The invention is diagrammatically illustrated by way of example in the accompanying drawings, in which:- Figure 1 is a block diagram of fuel injection apparatus according to a first embodiment of the invention; Figure 2 is a cross section of an injector according to the first embodiment; Figure 3 is a perspective view of a quantity control valve of this injector; Figure 4 is a cross section of the quantity control valve of the injector; Figure 5 is a front view of a control opening formed on the quantity control valve; Figure 6 is a flow chart of the operation of this injection apparatus; Figure 7 is a diagram of the injection pattern of the fuel injection apparatus obtained by the first embodiment; Figure 8 is a cross section of an injector of a modified embodiment; Figure 9 is a cross section of an injector according to a second embodiment; Figure 10 is a fuel injection pattern obtained by the injector of Figure 9; Figure 11 is a cross section of the injector according to a third embodiment; Figure 12 is a fuel injection pattern according to the injector of Figure 11; Figure 13 is a block diagram of a modified fuel injection apparatus; Figure 14 is a block diagram of a modified pump drive system; Figure 15 is a gearing diagram of the system of Figure 14; Figure 16 is a cross section of an injector according to a fourth embodiment of the invention; Figure 17 is a perspective view of the quantity control valve of the injector of Figure 16; Figure 18 is a cross section of the quantity control valve; Figure 19 is a diagram of an injection pattern obtained by the injector of Figure 16; Figure 20 is another diagram of an injection pattern obtained by this embodiment; Figure 21 is a cross section of an injector according to a fifth embodiment; Figure 22 is a perspective view of a quantity control valve of the fifth embodiment; Figure 23 is an enlarged cross section of the fuel control valve; Figure 24 is a front view of an oblong opening formed in the quantity control valve; Figure 25 is a front view of an actuator for the quantity control valve according to a sixth embodiment; and Figure 26 is a front view of a modified actuator. Referring to the drawings, and firstly to Figure 1, fuel is sucked from a fuel tank 201 by a high pressure feed pump 202. The pump 202 is driven by a direct current motor 203 and the motor 203 is controlled by a microcomputer 205 through a drive circuit 204. The fuel pumped by the high pressure feed pump 202 is pushed into and stored in an accumulator 206. The accumulator 206 is connected to an injector 208 by means of a feed pipe 207. An injection nozzle 209 is provided at the top end of the injector 208 and has a quantity control valve 210. The quantity control valve 210 is controlled by a control signal from the microcomputer 205. The injector 208 is provided on a cylinder head 213 which is fixed at the top of the cylinder 212 which receives slidably a piston 211. The construction of the injector 208 is shown in Figure 2. The injector 208 comprises a nozzle holder 216 which holds an injection nozzle 209 by means of a retainer 217. A solenoid coil 218 is provided in the nozzle holder 216. A plunger 219 is connected to the quantity control valve 210 by a connecting rod 220. A spring seat 221 is provided at the top of the plunger 219 and receives a coil spring 222. The spring seat 221 has a rod 223 projecting upward therefrom and an abutting plate 224 is connected to the top of the rod 223. A stepping motor 225 is arranged in the nozzle holder 216. A rotor 226 of the stepping motor 225 has a centre through hole 227 with a female thread. The female thread of the through hole 227 is engaged with a male thread formed on the periphery of the sleeve 228. A stopper rod 229 is situated so that the rod 229 goes through the sleeve 228. The rod 229 is connected to a plunger 231 situated at the centre of a solenoid coil 230. The plunger 231 is pushed downward by a coil spring 232 and hence the bottom end of the plunger 231 engages with a step 233 of the nozzle holder 216. The injection nozzle 209 has the quantity control valve 210 which is formed as a cylinder, as shown in Figure 3 and Figure 4, and the valve 210 has control openings 236 which extend axially. Slots 237 are formed at the both sides of the oblong openings 236. The valve 210 is received inside the injection nozzle 209 so that each control opening 236 coincides with an injection aperture 238 of the injection nozzle 209. On the internal peripheral surface of the injection nozzle 209, valve seats 239 are located at the edge of the injection aperture 238 and the quantity control valve 210 slides on the valve seat 239. In operation, the microcomputer 205 reads in the number of revolutions and the angular position of the engine through a revolution detecting sensor 240 and also reads in the load of the engine through a load sensor 241. Furthermore, the microcomputer 205 detects the pressure of the fuel in the accumulator 206 through the pressure sensor 242. The microcomputer 205 controls the motor 203 through the drive circuit 204 in order to maintain the pressure of fuel at a suitable value. The microcomputer 205 controls the solenoid coils 218, 230 and the stepping motor 225 in accordance with the flow chart shown in Figure 6 and gives the control valve 210 a stepping displacement, thereby to control the quantity of fuel injected at one time and also to open and close the injection aperture 238 of the injection nozzle 209. Thus, the microcomputer 205 detects the number of revolutions and load of the engine through the revolution detecting sensor 240 and the load sensor 241, and based on these informations the microcomputer 205 calculates the quantity of fuel injected at one time. This quantity corresponds to the height b in the injection pattern shown in Figure 7. To obtain the calculated quantity, the microcomputer 205 drives the stepping motor 225 which rotates the rotor 226 to a predetermined angular position. Then the sleeve 228 moves axially because the male thread of the sleeve 228 engages with the female thread 227 of the rotor 226. Therefore the gap b between the bottom end of the sleeve 228 and the top surface of the abutting plate 224 is regulated, and the stepping motor 225 is controlled. Then the microcomputer 205 calculates the timing of the injection, and moves the valve 210 at the proper moment so that the control opening 236 and the injection aperture 238 coincide. This operation starts fuel injection. That is, the microcomputer 205 energises the solenoid coil 218 at the proper time. Then the plunger 219 moves upward against the coil spring 222 and the abutting plate 224 provided at the top of the rod 223 makes contact with the stopper rod 229. Accordingly, the control valve 210 moves upwards in a stroke corresponding to the gap a between the abutting plate 224 and the stopper rod 229. Thus, the injection aperture 238 is slightly opened. Hence it is possible to decrease the quantity of fuel at the initial period of the injection, and a pilot injection is accomplished by this operation. When the stopper rod 229 which is connected to the plunger 231 is made of piezo electric material, the length of the rod 229 may be expandable to regulate the gap a to control the quantity of fuel at the initial period of injection. After the predetermined time duration from the start of the injection, the microcomputer 205 changes the fuel injection from pilot injection to main injection. That is, the microcomputer 205 energizes the solenoid coil 230 to displace upwardly the plunger 231 against the coil spring 232. Then the stopper rod 229 connected to the plunger 231 moves upward and is drawn inside the sleeve 228. Then the plunger 219 moves upwards until the abutting plate 224 comes in contact with the bottom end of the sleeve 228 because the plunger 219 is urged by the solenoid coil 218. As a result the quantity control valve 210 moves upwards with stepping displacement. Accordingly, the quantity control valve 210 moves upwards by the stroke b , thereby making the injection aperture 238 wide open. Since the effective area of the injection aperture 238 is proportionate to the stroke of the quantity control valve 210, the quantity of fuel injected is controlled by the quantity control valve 210. After a predetermined time has passed, the solenoid coils 218 and 230 are deenergised and the quantity control valve 210 is pushed downward by the coil spring 222. The quantity control valve 210 moves downward to a position where the control opening 236 does not coincide with the injection aperture 238 to close the injection aperture 238. In this way, the fuel injection is terminated. The fuel injection apparatus of this embodiment does not require the use of a periodical fuel injection pump, a mechanical governor or a mechanical timer thereof. Furthermore, according to this embodiment it is possible to control the apparatus by the microcomputer 205, and ensure that a suitable quantity of fuel is injected at the proper time. Additionally, according to this arrangement, a control of an injection pattern as shown in Figure 7 can be accomplished and it is possible to decrease the quantity of fuel at the initial period of the injection. Therefore, it becomes possible to decrease the noise of the engine and to decrease the quantity of nitrogen oxide in the exhaust gas. A modification of the first embodiment is described with reference to Figure 8. A feature of this modification is that the injector 208 includes another stepping motor 245. A rotor sleeve 246 of the stepping motor 245 has a centre hole 247 and the centre hole is threaded with a female screw which is engaged with a male screw of the stopper rod 229. Additionally, another solenoid coil 248 is provided under the solenoid coil 218. In operation, the stepping motor 225 regulates the gap b to control the quantity of the fuel of main injection. Another stepping motor 245 regulates the gap a to control the quantity of fuel in the pilot injection. At the proper moment the solenoid coil 218 is energized to displace the plunger 219 to a position where the abutting plate 224 makes contact with the stopper rod 229 by the force of the coil 218. The injection aperture 238 is then slightly opened by the control opening 236 of the valve 210 to accomplish the pilot injection. After a predetermined time has passed the second solenoid coil 248 is energized, and the upward force is increased. As a result, the sleeve 246 of the stepping motor 245 which holds the stopper rod 229 moves upward against the coil spring 232 and the abutting plate 224 makes contact with the bottom end of the sleeve 228 to displace the quantity control valve 210. In this way the injection aperture 238 is opened wide to accomplish the main injection of fuel. The quantity of fuel is increased at this moment and the stepping pattern shown in Figure 7 is accomplished as in the above-mentioned first embodiment. Furthermore, by this modification it is possible to control the quantity of fuel of the pilot injection by the second stepping motor 245. A second embodiment of this invention is shown in Figure 9 and Figure 10. A feature of this modification is that a linear stepping motor is used for the axial displacement of the quantity control valve 210. The slider 252 of the motor 251 is connected to the quantity control valve 210 by the connecting rod 220. A pair of guide members 253 and 254 are provided to ensure a smooth displacement of the slider 252. The microcomputer 205 controls the linear stepping motor 251 to displace the quantity control valve 210 resulting in the fuel injection pattern shown in Figure 10. According to this arrangement, a single linear stepping motor 251 moves the quantity control valve 210 in steps and hence it is possible to simplify the structure of the injector and minimize the number of motors 251. Furthermore, it is possible to eliminate the coil spring 222 when the return motion of the quantity control valve is also accomplished by the linear stepping motor 251. By this arrangement structure is more simplified. A third embodiment is described with reference to Figure 11 and Figure 12. In this embodiment, a moving coil 256 wound on a bobbin 255 is used for moving the quantity control valve 210. That is, the moving coil 256 constitutes the actuator for the control valve 210. The moving coil 256 wound on the bobbin 255 is connected to the control valve 210 by the connecting rod 220. The moving coil 256 is located between a centre pole 258 which is mounted at the top of a magnet 257 and an outside yoke 259. Upward or downward force is applied to the moving coil 256 in accordance with the principle of the voice coil of a dynamic speaker when an electric current is supplied to the moving coil 256. The quantity control valve 210 is moved by this force. A position detecting sensor 260 is provided to hold the quantity control valve 210 at a predetermined position. That is, the position detecting sensor 260 detects the position of the valve 210 and supplies a signal to the microcomputer 205 to control the moving coil 256. Thus, a feedback control is accomplished by the position detecting sensor 260. Accordingly, it is possible to simplify the structure of the actuator and also it is possible to control the injection pattern voluntarily and precisely as shown in Figure 12 to accomplish an ideal combustion of fuel. Figure 13 shows a modification of a pressured feed system. A feature of this modification is that a relief valve 262 is provided so that the accumulator can be eliminated. The relief value 262 is connected to the fuel feed pipe 207. A spring 263 of the valve 262 is controlled by the microcomputer 205 through an actuator 264 to control the relief pressure of the relief valve 262. The microcomputer 205 regulates the spring 263 through the actuator 264 in response to the pressure detecting sensor 242 precisely to control the pressure on which the relief valve 262 operates. Accordingly, it is possible to control the output pressure of the fuel feed pump 202 and to accomplish fuel injection without an accumulator. Figure 14 and Figure 15 show a modification of a feed pump drive system. A feature of this modification is that a differential gear apparatus 348 is used to drive the high pressure feed pump 302, instead of a direct current motor. The differential gear apparatus 348 is combined with an engine 347 and the rotary output speed of the apparatus is controlled by a direct current motor 303. A microcomputer 305 reads in the revolution number and the engine load through the revolution detecting sensor 345 and the load sensor 346. The motor 303 is controlled by the microcomputer 305 through a drive circuit 304. More specifically, a gear 349 takes out the torque of the engine 347 as shown in Figure 15 and the gear 349 is connected to a sun gear 350 which engages a planet gear 351. The planet gear 351 is supported by an arm 352. The arm 352 is fixed on the input shaft of the feed pump 302. The planet gear 351 supported by the arm 352 is engaged with an internal gear 353. The outside gear of the internal gear 353 is driven by a pinion 354 which is fixed on the output shaft of the motor 303. Accordingly, the torque of the engine 347 transmitted to the gear 349 is transformed to rotation of a pair of planet gears 351 by means of the sun gar 350. Therefore, the planet gears 351 makes the internal gear 353 revolve. The revolution is transmitted to the feed pump 302 by means of the arm 352. The motor 303 drives the internal gear 353 through the pinion 354. The revolutional speed of the arm 352 is increased when the motor 303 drives the internal gear 353 in the plus direction, and decreased when rotated in the minus direction. Furthermore, it is possible to stop the pump 302 by the motor 303. Therefore, it is possible to obtain torque from the engine 347 and control the number of revolutions of the feed pump 302 by the motor 303. The feed pump 302 may be a plunger pump, vane pump, or another kind of pump, and the feed pump may be made of a multistage pump to obtain the required output pressure. A fourth embodiment of this invention is described with reference to Figure 16 to Figure 20. A feature of this embodiment is that the control valve 310 of the injector 308 constitutes not only the quantity control valve but also the timing valve and that a column of piezoelectric element 338 is received in the nozzle holder 324 of the injector 308, and the bottom end of the column 338 is guided in the axial direction by a pair of projections 359 provided inside the nozzle holder 324. A cylindrical valve member 339 is connected to the piezoelectric element 338 by the connecting member 360 which has a feed hole 361 to feed fuel into the valve member 339. The piezo-electric element 338 has electrodes 362 which are connected to a drive circuit 363. The valve member 339 has the control openings 341 as shown in Figure 17 and Figure 18, and the control openings 341 control the effective area of the injection aperture 342 of the nozzle 326. Furthermore, longitudinal slots 364 are formed in the valve member 339. The slots 364 serve to deform the valve member 339 to contact the valve seat 365 by the pressure of the fuel. In operation the microcomputer 305 supplies a control signal to the drive circuit 363 to generate a pattern of voltage for the piezoelectric element 338 as shown in Figure 19 or Figure 20. As the voltage applied to the piezo-electric element 338 is substantially proportional to the stroke of the valve member 339, the injection aperture 342 is opened and the effective area of the injection aperture 342 is controlled by the control opening 341 of the valve member 339. Specifically, it is possible to obtain an injection pattern of ideal or suitable combustion when the quantity of fuel at the initial period of the injection is decreased as shown in Figure 20. Furthermore, in this arrangement, the valve member 339 moves to a position where the control opening 341 does not coincide with the injection aperture 342 when the voltage is relieved. This operation makes it possible to omit the timing valve, because the valve member 339 performs not only the quantity control valve function but also the timing valve function. Also, it is not necessary to use a timing control valve formed as a solenoid valve. Additionally the valve member 339 is pressed on the valve seat 365 of the nozzle 326 by the pressure of the fuel, and by this arrangement it is possible to close the injection aperture securely. The closing operation is assisted by the slots 364 which serve to deform the valve member 339. A fifth embodiment of the invention is described with reference to Figure 21 to Figure 24. Figure 21 shows an injector 408 which includes a nozzle holder 416 and a fuel feed pipe 407. A nozzle 409 is connected to the bottom of the nozzle holder 416 by a retainer 417. A pair of bimorph plates are arranged parallel and longitudinally in the nozzle holder 416. A rod 419 is secured with an adjusting screw 420 and the rod 419 has a bracket 421 which supports the top ends of the pair of bimorph plates 418 rotatably. The lower ends of the pair of bimorph plates 418 are connected rotatably to the quantity control valve 410 by a connecting rod 423. The quantity control valve 410 is cylindrical as shown in Figure 22 and Figure 23 and has control openings 424 or oblong openings and longitudinal slots 425 at both sides of the control openings 424. The quantity control valve 410 is arranged inside the nozzle 409 so that the control openings 424 coincide with an injection aperture 426 of the nozzle 409. The valve member 410 slides axially on a valve seat 427 formed on the internal peripheral surface of the nozzle 409 with the injection aperture 426. In operation the microcomputer 405 reads in the rotary speed and the angular position of the engine through a revolution detecting sensor, and the engine load through a load sensor. The microcomputer 405 also reads in the pressure of the fuel held in the accumulator (not shown) by a pressure sensor. The microcomputer 405 then controls the pump, through the motor to maintain the pressure of the fuel at a suitable value. The microcomputer 405 also controls the pair of bimorph plates 418 to displace the quantity control valve 410 thereby to control the quantity of fuel injected at one time. The control valve 410 opens and closes the injection hole 426 of the nozzle 409. Thus, the microcomputer 405 reads in the speed and the load of the engine, and then calculates the timing of the injection, the quantity of fuel, and the injection pattern based on the abovementioned information. Resulting from these calculations, the microcomputer 405 controls the drive circuit 433 which controls the voltage applied to the bimorph plates 418. The bimorph plates 418 deform as shown by the chain line in Figure 21 when electric voltage is applied. The pair of bimorph plates 418 deform in such a manner that intermediate portions of these plates 418 are separated from each other. As a result of this deformation the lower bracket 422 moves upward. This movement is transmitted to the quantity control valve 410 by the rod 423. Accordingly, as shown in Figure 24 the control opening 424 controls the effective area of the injection aperture 426, thus performing the quantity control operation. In the apparatus the quantity control valve 410 has sufficient stroke to close the injection aperture 426. Therefore, the quantity control valve 410 not only controls the quantity of fuel but also controls the opening and closing of the injection aperture 426. Furthermore, the injection pattern is controlled when the voltage applied to the bimorph plates 418 is controlled. More specifically, when the quantity of fuel at the initial stage of the fuel injection is decreased, it is possible to decrease the engine noise and amount of nitrogen oxide in the exhaust gas. As mentioned above, according to this embodiment, the control of fuel quantity, the injection timing, and the injection pattern are all accomplished by the quantity control valve 410 associated with the pair of bimorph plates 418. Furthermore, the control valve 410 is pressed against the valve seat 427 by the pressure of the fuel through the longitudinal slots 425 to accomplish perfect sealing operation when the quantity control valve 410 displaces to the position where the injection aperture 426 is closed. A sixth embodiment of this invention is described with reference to Figure 25 which shows a single bimorph plate 418 for displacing the quantity control valve 410. The bimorph plate 418 is disposed horizontally. One end of the plate 418 has a bracket 421' and the other end has a bracket 422' which is connected to an oblong opening 437 of a supporting bracket 436 by means of a pin 438 to permit the deformation of the bimorph plate 418 to the shape of arch. By this arrangement it is possible to displace the quantity control valve 410 by a relatively slight deformation of the intermediate portion of the bimorph plate 418. In this way the mechanism for opening and closing the quantity control valve 410 is simplified and is compact. A modification is shown in Figure 26, in which a single bimorph plate 418 is used and one end of the plate 418 is fixed. The free end of the plate 418 is connected to the quantity control valve 410 by a connecting rod 423. According to this arrangement, the mechanism for supporting the bimorph plate 418 is more simplified and hence the structure of the injector can be simple. An actuator of monomorph plate may be used instead of the bimorph plate in the last embodiment, and further magnetostrictive elements may be used for the actuator to control the displacement of the quantity control valve instead of the piezo-electric element. Furthermore, various materials may be used for the nozzle or the injector, and the nozzle may be made of ceramic materials to protect the quantity control valve or the piezo-electric element from heat. Furthermore, the invention is applicable not only to fuel injection apparatus of a Diesel engine but also to that of a gasoline engine when the pressure of the fuel is reduced.

Claims: Fuel injection apparatus for an engine, wherein fuel under substantially constant pressure is continuously supplied to an injector (208, 308, 408) to inject a mist of fuel, the injection apparatus comprising: an injection aperture (238, 342, 426) formed substantially laterally on the periphery of the injector to inject fuel; a quantity control valve (210, 310, 410) formed as a hollow cylinder to control the quantity of the fuel by regulating the effective area of the injection aperture; an actuator (218, 251, 256, 338, 418) to displace the quantity control valve axially in the injector; and electric control means (205, 305, 405) to control the actuator in response to speed of and load on the engine; characterized in that the actuator moves the quantity control valve in an axial stroke sufficient to close the injection aperture, thereby to operate the opening and closing of the injection aperture so that the quantity control valve serves as a timing control valve, and longitudinally extending slits or slots (237, 364, 425) are provided in the wall of the cylindrical quantity control valve to allow deformation of the wall by the pressure of the fuel so as to give close contact with an edge or a valve seat (239, 365, 427) of the injection aperture. Fuel injection apparatus according to claim 1, including a feed pump (202, 302) to pressurise the fuel, and an accumulator (206) to store the fuel under pressure, the fuel pressurised by the feed pump being pushed into the accumulator. Fuel injection apparatus according to claim 2, wherein the pressure of the fuel in the accumulator is detected by a pressure detecting sensor (242) and the feed pump is controlled in response to the detecting signal of the pressure detection sensor to maintain the pressure of the fuel in the accumulator substantially constant. Fuel injection apparatus according to claim 1, including a feed pump (202, 302) to pressurise the fuel, and a relief valve (262) connected to the feed pump, the relief pressure of the relief valve being controlled to maintain the output pressure of the feed pump substantially constant. Fuel injection apparatus according to claim 1, wherein the quantity control valve has a constant opening (236, 341, 424) to control the effective area of the injection aperture in response to the displacement thereof. Fuel injection apparatus according to claim 1, wherein the actuator operates as a stopper (228) of the quantity control valve, and the axial stroke of the quantity control valve is controlled by the stopper. Fuel injection apparatus according to claim 1, wherein the actuator is a magnetic coil (218). Fuel injection apparatus according to claim 1, wherein the actuator is a stepping motor (225, 251). Fuel injection apparatus according to claim 1, wherein the actuator is a linear motor (251). Fuel injection apparatus according to claim 1, wherein the actuator is a moving coil (256) and the position of the moving coil is detected by a position sensor (260), the moving coil driving the quantity control valve according to the principle of a dynamic speaker. Fuel injection apparatus according to claim 1, wherein the actuator is a piezo-electric element (338, 418). Fuel injection apparatus according to claim 11, wherein the piezo-electric element is made of the bimorph plate (418). A fuel injection apparatus according to claim 12, wherein the actuator is made of a pair of bimorph plates (418) which are longitudinally and parallely disposed and both ends of which are rotatably connected. Fuel injection apparatus according to claim 12, wherein one end of the bimorph plate (418) is fixed and the other free end of the bimorph plate is connected to the quantity control valve. Fuel injection apparatus according to claim 7, including a stopper (229) to restrict the stroke of the quantity control valve at the initial period of the fuel injection to accomplish a pilot injection, the pilot injection being released by another magnetic coil (230, 248) to step the quantity control valve and change the fuel injection from the pilot injection to main injection. Fuel injection apparatus according to claim 15, wherein the quantity of fuel of the pilot injection is constant. Fuel injection apparatus according to claim 15, including another actuator (245) to control the quantity of fuel of the pilot injection. Fuel injection apparatus according to claim 11, wherein electric voltage applied on the piezo-electric element (338, 418) is changed during the time duration of the injection thereby to displace the quantity control valve during the injection operation.

Inventors: MATSUMURA, OSAMU
Applicants: MATSUMURA, OSAMU
Application year: 1986
Main classification: F02M63
IPC codes: F02M61, F02M45, F02M51, F02M69, F02M63