The subject of the invention is an apparatus for diesel engines for the electronically controlled feeding of liquid or compressed gas for use in duplex diesel-gas fuelled vehicles, and a method for the application thereof. The apparatus is particularly suitable for being installed or retrofitted in either mechanically or electronically controlled engines. It is a well-known fact that the use of gas, particularly when stored in liquid form, as fuel for the operation of vehicle engines would be quite advantageous for environmental protection and financial reasons if the use thereof were not hindered by several obstacles. This is why alternative vehicles running either only gasoline or only gas have become widespread, retaining the advantages of running gasoline engines independent of gas supply.

Although diesel engines, in general, pollute the air to a lesser extent than gasoline engines and exhaust less carbon monoxide and unburned hydrocarbons, it may yet be disadvantageous that, following the injection of diesel oil into the cylinder, the chance of forming a homogeneous mixture degrades due to dispersion time being short and, therefore, black smoke is exhausted into the air if the engine is worn or adjusted incorrectly, etc. On the other hand, diesel engines cannot, without significant conversion, run on pure gas as fuel as the gas-air mixture compressed in the cylinders cannot explode without a spark-plug. This is why the idea, namely that gas in conventional diesel engines is used for improving combustion, came to light. Another major advantage is that the use of a gas-air mixture renders the mixing, dispersion and burning of diesel oil better and hence the engine's performance smoother and higher.

Based on this recognition, several solutions are known for feeding gas into diesel engines. Such is the solution appearing in Hungarian Patent Description No. HU 171 169 entitled "Method and apparatus for feeding diesel oil and propane butane gas into diesel engines". The essence thereof is that only diesel oil is added up to 70% of the engine's performance, and a mixture of diesel oil and gas is added thereafter. This solution assists by feeding gas only at a high diesel engine load although it would be required at medium and the most frequently used performance ranges. On the other hand, the likewise Hungarian description No. P8803102, entitled "Fuel feeding apparatus for gas-diesel engines", for the simultaneous regulation of liquid and gaseous substances describes an outdated and insufficiently demonstrated mechanical solution. The essence of the solution in Patent Description HU 223 128 entitled "Method and apparatus for the operation of vehicles equipped with diesel engines with a mixture of diesel oil and propane-butane gas" is that the automatically proportioned feeding of diesel oil and gas is combined with a mechanical rack-and-pinion feeding pump, which is completed with an electronic control unit. Today, most modern diesel engines employ electronic gas feeding and gas injection for which this apparatus is no longer appropriate. Installation of encoders on the rack-bar and into the engine block requires the partial modification of the engine.

According to British Patent Description GB 2437098 entitled "Engine running on two fuel types with appropriate fuel controllers", the engine is capable of running on two types of fuel rather than a mixture of them. To this end, it features ignition and a control unit for detecting the fuel type used and implementing switch-over accordingly. The solution in this invention necessitates a special engine configuration and control again. It cannot be connected to general-purpose diesel engines or used as a retrofitted gas feeding apparatus but rather as an entirely new complete engine construction.

In accordance with the embodiment of Patent Document US 7,509,209 entitled "Methods and apparatus for the operation of multiple fuel engines", the apparatus features a common electronic control unit governing the diesel engine and gas feeding, which can be connected to the existing components of an engine in order to control the operation of a multiple fuel engine. The engine system may be either mechanically or electronically controlled. In one solution, diesel oil is used as the primary fuel and natural gas as the secondary fuel. The operation of the engine is controlled by operating instructions (software) linked to the different characteristic curves of the engine. The unit that controls the feeding of gas and the injection of diesel oil is a complex apparatus in the vehicle and cannot be divided into separate components and thus cannot be retrofitted. It is a complex and expensive solution.

Thus, our task is to develop an apparatus and a method that comprise a mixed dual diesel oil and gas fuelled engine which is free from the deficiencies of the aforementioned solutions and can be retrofitted in electronically controlled or mechanically governed diesel engines that are used nowadays, without the need to modify or convert their existing control system. Another task is that the vehicle's emissions control system must not change after installing the apparatus described in the present invention, so that the existing diesel fuel system of the vehicle is retained. It should be easily installed and operated and should be able to operate using a single signal received from the engine, as well as complemented by its own sensors.

The invention is based on a recognition that if a sampling stub is installed into the inlet throat of a diesel engine and the current air pressure present in the inlet throat is transmitted through a pipe connected to the outlet of the sampling stub and used for the feedback control of the gas injection, gas feeding and decompression unit, then we achieved our goal and completed our task. If the foregoing is completed with the installation of a knock sensor and that the gas nozzle is combined with a reducer calibrated to the size of the engine, then a better and more reliable running of the engine is achieved.

The most general configuration of the invention is realized according to the primary apparatus and method claims. The individual configuration methods are included in the sub-claims. The apparatus and methods in the present invention are demonstrated in detail through figures where: Figure 1 is the arrangement drawing of the apparatus used for the electronic control of feeding liquid or compressed gas into the diesel engine,

Figure 2 is a magnified section of the apparatus in Figure 1 with the gas container and connected pipes,

Figure 3 is the front view of the gas injection nozzle,

Figure 4 is the longitudinal sectional view of the gas injection nozzle,

Figure 5 is the A- A sectional view of the gas injection nozzle,

Figure 6 is the magnified cross-sectional view of injection nozzle nose-piece. The top of Figure 1 shows an arrangement block diagram of the control units 5 of a well-known modern electronically controlled diesel engine 40 without gas feeding together with the key service modules thereof, the diesel engine signal transmitters 3 and the data transmitter cable harness 4 for diesel operation. A key part of the control unit 5 is the diesel engine data processor and central control unit 7 and the diesel engine control memory 9. The connection and the transfer of input and output signals are provided by a terminal strip 6 and a connecting cable harness 8. The diesel fuel injection valve 1, in which the diesel fuel 2 is fed, is controlled electronically through the valve control cable 10. The drawing shows with dotted line that the diesel engine 40 has electronically controlled diesel fuel injection valves 1 corresponding to the number of its cylinders. Six cylinders are displayed in Figure 1. All these, including the air filter 42, the devices and units providing for the operation of the diesel engine 40 even without gas, are not parts of the apparatus described in the present invention. According to the present invention, the diesel engine 40 is connected to the apparatus only through a single injection signal transfer cable 12. Thus, the precondition that the apparatus in the present invention does not directly interfere with the existing operation of the diesel engine 40 and that it can be retrofitted and removed, is also met.

The other parts of Figure 1 show the connections of the apparatus according to the present invention with the diesel engine 40 after installation. Figure 2 illustrates an enlarged part of the apparatus in the present invention, completed with the gas container 48, the gas feeder valve 49 and the multi-functional multi-valve 50. Figures 1 and 2 show that, according to the design in the sample, the apparatus in the present invention includes a feeder valve operating in a high pressure gas circuit, a magnetic valve 37 and a pressure reduction unit 35 which also serves as vaporizer, an electronically controlled unit which controls gas feeding 13 in the low pressure gas circuit, and a unit delivering gas into the air intake 41 of the diesel engine 40, which has a newly configured gas injection nozzle 32 according to our invention. The heating section of the pressure reduction unit 35 is connected to the cooling water system of the diesel engine 40 using the inlet pipe 51 and outlet pipe 52, to allow the vaporizer of the pressure reduction unit 35 to always remain at the optimum temperature. The unit which controls gas feeding 13 features a central gas operation data processing and control unit 15, a gas operation control memory 17, moreover the terminal strip 14 and an interconnecting cable harness 16 serving the same.

According to the invention, there is a sampling stub 47 installed in the air intake 41 of the diesel engine 40, which is partly connected to the pressure reduction unit 35 through the pipe 44, and partly connected to the comparator unit 28 which compares the pressure in the air intake 41 with the pressure in the gas injection valve 30 through the pipe 43. The operation of the invention described in Figures 1 and 2 can be best followed by demonstrating the method according to the present invention. First, the gas container 48 of the vehicle is filled with liquefied or compressed gas through the gas feeder valve 49 at an appropriate filling station. Please note that due to safety regulations, the gas container 48 is equipped with a multi-functional multi-valve 50, which measures the fuel level of the gas container 48 and the pressure of the gas therein at the same time. In addition to the feeder and connection valves, the multi-valve 50 is also equipped with a pressure limiting safety valve. The gas stored in the gas container 48 is delivered through the high pressure pipe 38 to the feeder valve, preferably to the magnetic valve 37. Also see Figure 2. The high pressure gas is delivered to the pressure reduction unit 35 from the magnetic valve 37 through the high pressure pipe 36, where low pressure gas is obtained through vaporization. Vaporization causes heat removal, therefore, the heater part of the pressure reduction unit 35 is connected to the cooling water system of the diesel engine 40 through the inlet pipe 51 and outlet pipe 52 to ensure an optimum operating temperature. From the pressure reduction unit 35, the low pressure gas is delivered through the gas feeder pipe 46 to the gas injection valve 30 configured according to the present invention, which is electronically controlled by the unit which controls gas feeding 13. The gas, fed by the gas injection valve 30, is delivered through the interconnecting pipe 39 and the reducer 31, calibrated to the size of the diesel engine 40, to the gas injection nozzle 32 which introduces the gas into the air intake 41 of the diesel engine 40. To achieve better and more perfect gas-air mixing, the recessed part 56 of the gas injection nozzle 32 is fitted with a nose-piece 57. Also see Figure 3. It is also possible to integrate the gas injection nozzle 32 and the reducer 31, calibrated to the size of the diesel engine 40. Thus, diesel engines 40 of various types and sizes can be served by simply replacing the gas injection nozzle 32.

Pursuant to our invention, a sampling stub 47 is installed in the air intake 41 of the diesel engine 40 and the prevailing air pressure in the air intake 41 is used for control, whether it is normal, turbo charged or compressor. Thus, the apparatus in the present invention automatically becomes suitable for any kind of diesel engine 40, including suction, turbo charged and compressor. Part of the air is directed from the sampling stub 47 through the pipe 44 to the pressure reduction unit 35 where the pressure reduction unit 35 is controlled by the pressure of air, preferably by way of its membrane 58. The rest of the air is directed from the sampling stub 47 through the pipe 43 to the comparator unit 28 where this air pressure is compared to that of the gas which comes from the gas injection valve 30 received through the gas pressure transmitting pipe 45. The result of the comparison is communicated through the comparator cable 27 to the unit which controls gas feeding 13. Then, the electronically controlled unit which controls gas feeding 13 is used to regulate the gas injection valve 30 through the control cable 29 so that the pressure of the gas exiting the gas injection nozzle 32 is always higher than the pressure in the air intake 41. The apparatus in the present invention can be installed for the purpose of achieving dual diesel-gas operation not only in electronically controlled diesel engines 40 that are commonly used nowadays but also in diesel engines with mechanically controlled diesel oil injection. In the latter case, the single control signal for the apparatus according to the present invention is provided by the mechanically controlled diesel engine signal source 11 shown in the figure with a dotted line. The preferred embodiment of the apparatus in the present invention also possesses gas operation encoders 18 and a data transmission cable harness 19 that transmits the signals thereof. Of the gas operation encoders 18, the roles and structures of the revolution sensor 20, the speed sensor 21, the gas pedal angular rotation sensor 22 and the butterfly valve angular rotation sensor 25 are known. Therefore, their use, role and connection - as necessary and varying depending on engine type - is not presented separately. We wish to draw attention to the fact that the feeding of gas is stopped in case of engine braking mode using the butterfly valve angular rotation sensor 25, and the feeding of gas is also stopped by the speed sensor 21 if the vehicle is stationary. Cautious and safe operation is ensured by the pressure reduction unit 35 being equipped with an engine cooling water temperature probe 34 whose signal is transferred through the temperature data cable 33 to the unit which controls gas feeding 13.

The apparatus in the present invention is preferably equipped with a knock transmitter 23 and a knock sensor 24 mounted on the diesel engine 40. A knock sensor 24 is mounted on the diesel engine 40 and is connected with an electric cable to the knock transmitter 23 comprising a preferably analogue-to-digital signal converter. Furthermore, the knock transmitter 23 is also connected via a signal transmission chain with the central gas operation data processing and control unit 15 in order to transmit signals. The signal transmission chain preferably comprises a gas operation data transmission cable harness 19, a terminal strip 14 and an interconnecting cable harness 16.

According to our method, a knock sensor 24 is installed in the diesel engine 40. The analog knocking signal is generated using a piezoelectric crystal and then the analog signal received is forwarded to the knock transmitter 23 where the analog signal is converted into a digital one. The so obtained digital signal is introduced through the gas operation data transmission cable harness 19 into the unit which controls gas feeding 13, where the feeding of gas in the apparatus is stopped in case knocking is detected. Once knocking ceases, the feeding of gas is resumed, preferably gradually, while the subsequent signals of the gas operation encoders 18 are monitored and evaluated. Corresponding to the state of the art, the apparatus in the present invention is also equipped with a diagnostic and programming unit 26 which is connected to the unit which controls gas feeding 13. The role of this unit is to electronically detect any failure and to restore operation of the apparatus as required. The gas injection nozzle 32 of the invention is further detailed in figures 3, 4, 5 and 6. Figure 3 shows the front view of the gas injection nozzle 32, while Figure 4 presents its axial sectional view where the round threaded part 53, the nozzle box 54, the external threaded part 55, the recessed part 56 into the air intake 41 and the nose-piece 57 are located. The interconnecting pipe 39 is connected to the gas injection nozzle 32 by its round threaded part 53, preferably through a reducer 31. The gas injection nozzle 32 is screwed into the air intake 41 by the external threaded part 55. The enlarged configuration of the nose-piece 57 on the recessed part 56 which extends into the air intake 41 according to the present invention is shown in Figure 6. Figure 5 contains an A-A sectional view of the gas injection nozzle 32. If the reducer 31 is integrated with the gas injection nozzle 32, it can be configured inside the nozzle box 54, e.g., by narrowing it.

An advantage of the apparatus is that it can be installed in any diesel engine currently sold without directly interfering with its operation. The original fuel system would remain unchanged and the emissions control system is not modified, either. The use of the apparatus is independent of whether the air supply method of the diesel engine is normal, suction, turbo charged or compressor. It can be easily installed and used. It is capable of running with a single signal received from the engine, where the signal is to be preferably obtained from the control of the diesel fuel injection valve. However, if so required, the apparatus can be operated using the revolution signal of mechanically controlled diesel engines. If so, a simple method for generating the revolution signal is the hall sensor. The installation and use of the knock sensor will facilitate safer operation and overloading of the diesel engine can also be avoided.

Another advantage of the apparatus compared to other known gas injection systems is that it can use the same high performance gas injection valve in a wide performance range. The reason is that the gas exiting the gas injection valve feeding the gas is delivered to the air intake through a separate gas injection nozzle, either equipped with a reducer calibrated according to the type and output of the diesel engine or integrated with it. Another advantage thereof is that injection lasts longer and the pulse and fluctuation of gas feeding decreases, thus ensuring a constant gas feed. These advantages are further enhanced by the configuration of the gas injection nozzle and the nose-piece as it allows for better air-gas mixing due to its configuration improving the mixing of gas than known gas/air mixing pieces that still limit or block the volume of air entering the diesel engines.