Patent Description:
<CIT> discloses a method for testing an injector valve for liquid gas such as methanol. The injector valve may be used for a two-stroke combustion engine. The injector valve is supplied with sealing oil and control oil for controlling the supply of liquid gas. The disclosed injector valve holds a plunger piston chamber for forming a compression chamber, a suction valve with a suction piston and a nozzle valve with a nozzle piston, one or more nozzle openings, and a control oil channel, wherein the fuel fluid channels provide a fluid connection from the plunger piston chamber to the nozzle openings when the suction valve is open by a pressure on the suction piston provided by a fluid pressure in the plunger piston chamber and when the nozzle valve is open by a pressure on the nozzle piston provided by a control oil pressure supplied via the control oil channel. For the test disclosed in <CIT>, the injector valve is placed in a holder and the top cover is removed and substituted with a connecting piece and the pressure of the control oil is increased until the opening pressure for the nozzle valve is reached and the injector valve sprays oil from the nozzle openings into a spray chamber. As a result, the opening pressure of the nozzle valve can be checked. However, there is no disclosure of a leakage test of the suction valve.

A new injector valve for methanol for a two-stroke combustion engine has been developed by MAN Diesel & Turbo. The injector valve is supplied with sealing oil and control oil for controlling the supply of liquid gas. Leaks if any could be very dangerous.

Thus, there is a need for an improved method for testing an injector valve for leaks, and there is also a need for an improved working test of an injector valve.

It is an object of the present disclosure to provide an improved method for testing an injector valve for valve leaks.

This object is achieved in accordance with the invention defined in claim <NUM> by providing a method of testing a valve body of an injector valve for a combustion engine, which valve body holds
a plunger piston chamber for forming a compression chamber, a suction valve with a suction piston, one or more fuel fluid channels, a nozzle valve with a nozzle piston, one or more nozzle openings, and a control oil channel, wherein the fuel fluid channels provide a fluid connection from the plunger piston chamber to the nozzle openings when the suction valve is open by a pressure on the suction piston provided by a fluid pressure in the plunger piston chamber and when the nozzle valve is open by a pressure on the nozzle piston provided by a control oil pressure supplied via the control oil channel; said method comprising:.

The supplied test gas may reach via the suction valve, the fuel fluid channels, the nozzle valve and out through the nozzle openings.

In a possible implementation form, a flexible hose is connected to the nozzle openings and further connected to a separate container with liquid, whereby any test gas reaching through the nozzle openings into the flexible hose is observed as bubbles in the liquid of the container. The liquid may be water.

If any gas bubbles are observed in in the separate container, the suction valve is not completely tight. If no bubbles are observed, the suction valve is tight.

In a possible implementation form, the control oil is supplied at a first control oil pressure in the range of <NUM>-<NUM> bar, such as about <NUM> bar.

In a possible implementation form, the test gas is supplied at a first test gas pressure below <NUM> bar.

In a possible implementation form, the method further comprises:.

In a possible implementation form, the step of checking the amount of test gas reaching out through the nozzle openings comprises checking the amount of test gas bubbles in the liquid of the separate container.

If an increased amount of test gas bubbles is observed in when compared to the amount of test gas bubbles observed at the first test gas pressure, the suction valve is open as required.

In a possible implementation form, the test gas being supplied at the second test gas pressure is supplied at a pressure being above <NUM> bar, such as not below <NUM> bar, such as not below <NUM> bar, such as about <NUM> bar.

In a possible implementation form, the step of checking whether any test gas reaches out through the nozzle openings or not comprises checking whether there are any test gas bubbles or not in the liquid of the separate container.

In a possible implementation form, the test gas being supplied at a pressure being above or equal to the predetermined test gas opening pressure required for opening the suction valve is supplied at a pressure being above <NUM> bar, such as not below <NUM> bar, such as not below <NUM> bar, such as about <NUM> bar.

If any test gas bubbles are observed, the nozzle valve is not completely tight. If no bubbles are observed, the nozzle valve is tight.

In a possible implementation form, a connecting piece is provided, said connecting piece having a top part with a first fluid inlet port and a second fluid inlet port and further having a dummy thrust piece holding a test fluid channel in fluid connection with the second fluid inlet port, and wherein before the steps of supplying control oil and test gas, the method comprises.

In a possible implementation form, the injector valve further comprises:.

In a possible implementation form, the top cover further holds a sealing oil inlet port, and the valve body holds a sealing oil channel and a nozzle valve chamber holding the nozzle piston, which sealing oil channel is in fluid connection with the sealing oil inlet port, in fluid connection with the plunger piston chamber for sealing the plunger piston, and in fluid connection with the nozzle valve chamber for sealing the nozzle piston.

In a possible implementation form, the valve body further comprises:.

In a possible implementation form, then before the step of connecting the connecting piece to the valve body, the method comprises disconnecting the top cover and the plunger piston from the valve body.

In a possible implementation form of the first aspect, the test gas in a non-burnable gas, such as Nitrogen.

These and other aspects of the invention will be apparent from the embodiments described below.

An injector valve according to a preferred embodiment is designed by MAN Diesel & Turbo for a two-stroke combustion engine. The engine is a duel fuel engine, which can run on standard heavy fuel oil or on a liquefied petroleum gas, LGP, such as propane.

The injector valve may be used as a fuel booster injection valve for the liquefied petroleum gas, LGP, and may be designed for performing two functions: to pressurize or boost the LPG to the desired injection pressure, and to ensure the correct timing and duration of the LPG injection.

During normal operation, the injector valve is supplied with sealing oil, plunge oil, control oil, and liquid petroleum gas, LPG, as fuel. Sealing oil is to prevent internal leak of liquid gas from entering unintended areas of the injector valve. Plunge oil is to pressurize the fuel, LPG. Control oil is to control the timing of opening the injector valve for delivering compressed fuel gas to the combustion chamber. Liquid fuel is supplied to the injector valve constantly.

An embodiment of the injector valve <NUM>, an embodiment of a valve holder <NUM> and a connecting piece <NUM> used for testing the injector valve are described in the following with reference to <FIG>.

The injector valve <NUM> holds a top cover <NUM>, see <FIG>, <FIG>, <FIG>, a plunger piston <NUM>, and a valve body <NUM>, and when the injector valve is assembled, the plunger piston <NUM> is inserted into a plunger piston chamber <NUM> hold by the valve body <NUM>, with the top cover <NUM> secured on top of the valve body <NUM>, leaving the plunger piston <NUM> to be moved within the plunger piston chamber <NUM>.

The top cover <NUM> holds a plunge oil inlet port 12a, a control oil inlet port <NUM> and a sealing oil inlet port <NUM>, see <FIG>. The top cover <NUM> further holds a cover chamber 12b in direct fluid connection with the plunge oil inlet part 12a, and in fluid connection with the control oil inlet port <NUM> via two cover fluid channels 15a, 15b, see <FIG>, which is a cross-sectional cut through view of the top cover <NUM> to illustrate the channels 15a and <NUM> providing the fluid connection between the plunge oil inlet port 12a and the control oil inlet port <NUM>.

The plunger piston <NUM> holds a plunger chamber <NUM>, a plunger valve <NUM> formed by a plunger valve piston <NUM> and a plunger valve spring <NUM>, see <FIG>, <FIG>, and plunger fluid channels <NUM>, see <FIG>, where the plunger fluid channels <NUM> provide a fluid connection from the plunger chamber <NUM> to the bottom of the plunger piston <NUM> when the plunger valve <NUM> is open by the plunger valve piston <NUM> being pressed downwards. When the plunger piston <NUM> is inserted into the plunger piston chamber <NUM>, a compression chamber <NUM> is formed in the valve body <NUM> below the bottom of the plunger piston <NUM>, where the compression chamber <NUM> is in fluid connection with the plunger chamber <NUM> via the plunger fluid channels <NUM> when the plunger valve <NUM> is open. The downwards movement of the plunger piston <NUM> may be controlled by oil supplied to the cover chamber 12b from the plunge oil inlet port 12a.

The valve body <NUM> holds a first fuel inlet port <NUM> in fluid connection with the plunger chamber <NUM> via a first fuel inlet channel 27a, see <FIG> and <FIG>, whereby a pressure provided by a fuel fluid supplied from the first fuel inlet port <NUM> to the plunger chamber <NUM> may open the plunger valve <NUM>, whereby the fuel fluid may flow form the plunger chamber into the compression chamber <NUM> via the plunger fluid channels <NUM>. The valve body also holds a second fuel inlet port <NUM> in direct fluid connection with the compression chamber <NUM> via a second fuel inlet channel <NUM>, see <FIG> and <FIG>.

The plunger chamber <NUM> and the part of the first fuel inlet channel 27a feeding the fuel fluid to the plunger chamber <NUM> are configured so as to provide the fuel fluid connection between the first fuel inlet port <NUM> and the plunger chamber <NUM> at all positions of the plunger piston <NUM>. The compression chamber <NUM> and the second fuel inlet channel <NUM> are configured to provide the fuel fluid connection between the second fuel inlet port <NUM> and the compression chamber <NUM> when the plunger piston <NUM> is in an uppermost position when no control oil pressure is supplied to the plunger piston <NUM> and further configured to close the fuel fluid connection between the second fuel inlet port <NUM> and the compression chamber <NUM> when the plunge piston <NUM> is moved downwards by an oil pressure supplied via the cover chamber 12b.

The valve body <NUM> holds a suction valve chamber <NUM> with a suction valve <NUM> positioned at the bottom of the compression chamber <NUM>, see <FIG>, where the suction valve <NUM> includes a suction piston <NUM> and a suction piston spring <NUM>. The valve body <NUM> also holds a nozzle valve chamber <NUM> with a nozzle valve <NUM> including a nozzle piston <NUM> and a nozzle piston spring <NUM>. The bottom of the valve body <NUM> holds a nozzle <NUM> with nozzle openings <NUM> for output of the liquid fuel. A number of fuel fluid channels <NUM> are formed in the valve body <NUM>, see <FIG> and <FIG>, where the fuel fluid channels <NUM> are configured to provide a fluid connection from the compression chamber <NUM> to the nozzle openings <NUM> when the suction valve <NUM> is open by a pressure on the suction piston <NUM> provided by a fluid pressure in the compression chamber <NUM> and when the nozzle valve <NUM> is open by a pressure on the nozzle piston <NUM>.

A control oil channel <NUM> is provided in the valve body <NUM>, see <FIG> and <FIG>, where control oil is supplied to the control oil channel via the control oil inlet port <NUM> during normal operation. The control oil channel <NUM> is configured to provide a pressure for upwards movement of the nozzle piston <NUM> to thereby open the nozzle valve <NUM> and allowing the liquid fuel to escape through the nozzle openings <NUM>.

Besides supplying fuel fluid to the plunger chamber <NUM>, the first fuel inlet port <NUM> also supplies fuel fluid via first fuel inlet channel 27b to the suction valve chamber <NUM> via a suction valve fuel oil channel <NUM> to thereby assist the suction piston spring <NUM> in providing an upwards pressure on the suction piston <NUM>, see <FIG>. The first fuel inlet port <NUM> further supplies fuel fluid via first fuel inlet channel 27b to a nozzle piston fuel oil chamber <NUM> surrounding the nozzle piston <NUM>.

A sealing oil channel <NUM> is provided in the valve body <NUM>, where sealing oil is supplied to the sealing oil channel via the sealing oil inlet port <NUM> during normal operation, see <FIG>. The sealing oil channel <NUM> is configured to deliver sealing oil to a plunger piston sealing chamber <NUM> for sealing the plunger piston <NUM> within the plunger piston chamber <NUM>, see <FIG> and <FIG>, and to deliver sealing oil to the nozzle valve chamber <NUM> holding the nozzle valve spring <NUM>, see <FIG>. The nozzle piston <NUM> holds a nozzle piston oil channel <NUM>, which is in fluid connection with a nozzle piston sealing chamber <NUM> surrounding the nozzle piston <NUM>, see <FIG>. The sealing oil passes nozzle valve spring <NUM> and flows via the nozzle piston oil channel <NUM> into the nozzle piston sealing chamber <NUM> for sealing the nozzle piston <NUM> and to provide a downwards pressure on the nozzle piston <NUM>.

<FIG> is an amplified longitudinal sectional view showing the suction valve <NUM> of the injector valve <NUM> below the compression chamber <NUM>, where the suction piston <NUM> is in an uppermost position closing the suction valve <NUM> and thereby closing for fluid flow from the compression chamber <NUM> and into the fuel fluid channels <NUM>. <FIG> shows the situation where the suction piston <NUM> has been pressed downwards to thereby open the suction valve <NUM> for providing a fluid connection between the compression chamber <NUM> and the fuel fluid channels <NUM>.

<FIG> is an amplified view of a lower part of the sectional view of <FIG> illustrating the situation for which the nozzle valve <NUM> is open with the nozzle piston <NUM> being pressed upwards to thereby provide a fluid connection between the fuel fluid channels <NUM> and the nozzle openings <NUM>.

<FIG> and <FIG> illustrate the injector valve <NUM> of <FIG> when placed in the valve holder <NUM> for testing of the assembled injector valve <NUM>, where the valve holder <NUM> is connected to a spray chamber 5a. The valve holder <NUM> is provided with a top plate 2a and a lower plate 2b, where the lower plate 2b is connected to the spray chamber 5a. The injector valve <NUM> is connected to the valve holder <NUM> by upper nuts 3a securing the top cover <NUM> to the top plate 2a, and by lower nuts securing the top plate 2a to the lower plate 2b. The valve holder <NUM> is provided with a fuel inlet 4a for inlet of fuel fluid to the first and second inlet ports <NUM> and <NUM> of the valve body <NUM>, see <FIG>, and further provided with a leak outlet 4b for outlet of any oil being leaked from the injector valve <NUM> during a test. The upper part of the valve body <NUM> is inserted into an opening in the top plate 2a, while the nozzle <NUM> of the valve body <NUM> reaches through an opening in the lower plate 2b into the spray chamber 5a.

<FIG> shows how the valve body <NUM> is placed in the valve holder <NUM> with the first fuel inlet port <NUM> positioned in fluid connection with the fuel inlet 4a of the valve holder <NUM>. The inside of the valve holder <NUM> and the outside of the valve body <NUM> are formed so as to provide a fuel inlet chamber surrounding the valve body <NUM> and being sealed by a lower sealing ring and an upper sealing ring. Both the first fuel inlet port <NUM> and the second fuel inlet port <NUM> reach into this fuel inlet chamber, whereby fuel oil can be supplied via the fuel inlet 4a to both the first and second fuel inlet ports <NUM> and <NUM>.

In order to test whether the suction valve <NUM> and the nozzle valve <NUM> are tight, a connecting piece <NUM> is provided. For this kind of test, the top cover <NUM> and the plunger piston <NUM> are disconnected from the valve body <NUM>, and the connecting piece <NUM> is inserted into the plunger piston chamber <NUM> of the valve body <NUM>.

<FIG> illustrates an embodiment of such a connecting piece <NUM> to be placed in the valve body <NUM> of injector valve <NUM> of <FIG>, when the top cover <NUM> and the plunger piston <NUM> are removed from the valve body <NUM>. The connecting piece <NUM> holds a top part <NUM> with a top part first fluid inlet port 8a and a top part second fluid inlet port 8b and a dummy thrust piece 9a extending below the top part <NUM>. The dummy thrust piece 9a holds a throughgoing thrust piece fluid channel 9b, see <FIG>, which at the top is connected to the top part first fluid inlet port 8a for supply of fluid and which is open at the bottom for output of fluid.

<FIG> illustrates the injector valve <NUM> placed in the valve holder <NUM> and the spray chamber 5a when the top cover <NUM> and plunger piston <NUM> are replaced by the connecting piece <NUM>.

The top part <NUM> of the connecting piece <NUM> is secured to the valve body <NUM> by connecting piece nuts 8c. The valve holder <NUM> is provided with a top plate 2a and a lower plate 2b, where the lower plate 2b is connected to the spray chamber 5a. The valve body <NUM> and the connecting piece <NUM> is connected to the valve holder <NUM> by upper nuts 3a securing the top part <NUM> of the connecting piece <NUM> to the top plate 2a, and by lower nuts securing the top plate 2a to the lower plate 2b. The valve holder <NUM> may be provided with a fuel inlet 4a for inlet of fuel fluid to the first and second inlet ports <NUM> and <NUM> of the valve body <NUM>, see <FIG>, and further provided with a leak outlet 4b for outlet of any oil being leaked from the injector valve <NUM> during a test. However, for testing the suction valve <NUM> and the nozzle valve <NUM>, there is no fuel inlet to the valve body <NUM> through the fuel inlet 4a.

In a preferred embodiment for testing the suction valve <NUM> and the nozzle valve <NUM>, the spray chamber 5a is replaced by a flexible hose 5b, which is in fluid connection with the nozzle openings <NUM> of the valve body <NUM> and further connected to a separate container 5c holding a liquid, such as water, see <FIG>. The nozzle openings <NUM> are connected to a pipe having a pipe end connected to a non-return valve 5d, and a pipe outlet with a relatively small diameter, such as a diameter of <NUM>,<NUM>, being connected to the flexible hose 5b. The non-return valve 5d may be designed for opening at a pressure of <NUM> bar. Thus, if any test gas is output from the nozzle openings <NUM>, this test gas can be observed as bubbles in the liquid of the separate container 5c, and if the pressure of the test gas being output from the nozzle openings <NUM> gets above the opening pressure of the non-return valve 5d, this valve 5d will open in order to avoid too much test gas spraying out through the liquid in the separate container 5c.

<FIG> is a longitudinal sectional view of the valve body <NUM> with the connecting piece <NUM> inserted into the plunger piston chamber <NUM> when placed in the valve holder <NUM>, see also <FIG>. The top part <NUM> of the connecting piece <NUM> is secured to the valve body <NUM> by connecting piece nuts 8c. The valve holder <NUM> is provided with a top plate 2a and a lower plate 2b, where the lower plate 2b is connected to the spray chamber 5a. The valve body <NUM> and the connecting piece <NUM> is connected to the valve holder <NUM> by upper nuts 3a securing the top part <NUM> of the connecting piece <NUM> to the top plate 2a, and by lower nuts securing the top plate 2a to the lower plate 2b. The valve holder <NUM> may be provided with a fuel inlet 4a, but for testing the suction valve <NUM> and the nozzle valve <NUM>, there is no fuel inlet to the valve body <NUM> through the fuel inlet 4a.

<FIG> shows how the dummy thrust piece 9a is inserted into the plunger piston chamber <NUM> with the throughgoing thrust piece fluid channel 9b connected to the top part first fluid inlet port 8a for supply of fluid and with a bottom opening reaching through the bottom of the plunger piston chamber <NUM> in order to deliver a fluid pressure on the suction valve <NUM>. <FIG> also shows the arrangement of the nozzle valve <NUM> with the nozzle valve spring, and the nozzle <NUM> going though an opening in the lower plate 2b of the valve holder <NUM> in order to allow a fluid output from the nozzle openings below the lower plate 2b. When both the suction valve <NUM> and the nozzle valve <NUM> are open, then a fluid delivered through the thrust piece fluid channel 9b will pass the suction valve <NUM>, flow through the fuel fluid channels <NUM>, see <FIG>, and pass the nozzle valve <NUM> into the nozzle openings <NUM>.

<FIG> is a diagram of a test system <NUM> with lines for supply of control oil 100d and test gas 100c for testing the suction valve <NUM> and the nozzle valve <NUM> of the valve body <NUM> of the injector valve <NUM> of <FIG>, for which test the top cover <NUM> and the plunger piston <NUM> are replaced by the connecting piece <NUM> of <FIG>.

For this test, the valve body <NUM> with the connecting piece <NUM> inserted into the plunger piston chamber <NUM> is placed in the valve holder <NUM>, see also <FIG> and <FIG>. A test gas in the form of Nitrogen is supplied from the system <NUM> via a gas outlet 100c to the first fluid inlet port 8a of the top part <NUM> of the connecting piece <NUM>, and control oil is supplied via a control oil outlet 100d to the second fluid inlet port 8b of the top part <NUM>. The nozzle openings <NUM> are connected to a pipe having a pipe end connected to the non-return valve 5d, where the pipe outlet placed before the non-return valve 5d is connected to the flexible hose 5b, which flexible hose 5b ends in the liquid of the separate chamber 5c, whereby test gas may flowing out through the nozzle openings can bae observed as bubbles in the liquid of the separate container 5c.

The test system <NUM> illustrated in <FIG> and <FIG> comprises an air inlet 100b for inlet of air at a pressure in the range of <NUM> - <NUM> bar, which pressurized air is used as input to three pressure control valves, a control oil pressure control valve <NUM>, a sealing oil pressure control valve <NUM>, and a fuel oil pressure control valve <NUM>. A gas inlet 100a is provided for inlet of a test gas in the form of Nitrogen at a pressure in the range of <NUM>-<NUM> bar. The pressurized Nitrogen is supplied to a gas stop valve <NUM>, with a gas pressure control valve <NUM> being provided for controlling the pressure of the gas being output from the gas stop valve <NUM> to the gas outlet 100c. A gas pressure relief valve <NUM> is connected to the gas line connection between the gas stop valve <NUM> and the gas outlet 100c and the gas pressure can be read from a gas pressure gauge <NUM>.

In order to deliver a test fluid in the form of a hydraulic oil, which may be a mineral hydraulic oil with a viscosity of <NUM> centistokes (cSt), and oil thank <NUM> holding the hydraulic oil is provided. An outlet of the oil tank <NUM> is connected to three air driven pumps, a control oil air driven pump <NUM> being controlled by the control oil pressure control valve <NUM>, a sealing oil air driven pump <NUM> being controlled by the sealing oil pressure control valve <NUM>, and a fuel oil air driven pump <NUM> being controlled by the fuel oil pressure control valve <NUM>. The oil pressure from the control oil air driven pump <NUM> can be read from a control oil pressure gauge <NUM>, and the oil pressure from the control oil air driven pump <NUM> can be released by a control oil pressure relief valve <NUM>, in which case released hydraulic oil will flow back to the oil tank <NUM>.

A hydraulic accumulator <NUM> is provided, which accumulator <NUM> may be charged by opening or closing a control oil stop valve <NUM>. A control oil pressure safety valve <NUM> is provided as a safety valve adjusted to a maximum working pressure of <NUM> bar for the hydraulic accumulator <NUM> in order to protect the accumulator <NUM> against too high pressure. The hydraulic accumulator <NUM> is a membrane type of accumulator. It has a chamber which is divided by a rubber membrane. On one side of the membrane is Nitrogen at a pressure of <NUM> bar, on the other side of the membrane is hydraulic oil supplied from the control oil air driven pump <NUM>. While the pressure of hydraulic oil is <NUM> bar, then the whole volume of accumulator is filled with Nitrogen. While applying hydraulic oil at a pressure above <NUM> bar, then the Nitrogen will start compress, as the hydraulic oil will start filling the volume of hydraulic accumulator. The purpose of the accumulator <NUM> in the test system <NUM> is to accumulate hydraulic oil inside with a pressure. While releasing oil pressure it is possible to get a high peak oil flow output from the accumulator <NUM>.

A control oil directional valve <NUM> is provided for opening or closing of control oil supply from the control oil air drive pump <NUM> and the hydraulic accumulator <NUM> to a control oil outlet 100d. While testing the assembled injector valve <NUM>, it is necessary to provide control oil with a high flow in a short time through the control oil directional valve <NUM> to the control oil outlet 100d. The pump <NUM> is not able to provide the required control oil flow alone, wherefore the high peak control oil delivery from the hydraulic accumulator <NUM> is needed.

Sealing oil is provided from the sealing oil air driven pump <NUM> to a sealing oil outlet 100e, and the oil pressure from the sealing oil air driven pump <NUM> can be read from a sealing oil pressure gauge <NUM>, while the oil pressure from the sealing oil air driven pump <NUM> can be released by a sealing oil pressure relief valve <NUM>, in which case released hydraulic oil will flow back to the oil tank <NUM>. A sealing oil pressure safety valve <NUM> is provided for protection of the sealing oil pressure gauge <NUM>. The sealing oil pressure safety valve <NUM> is adjusted to a maximum working pressure of <NUM> bar at the output side of the sealing oil air driven pump <NUM>. If the sealing oil pressure exceeds the <NUM> bar, the sealing oil safety valve <NUM> will open and hydraulic oil will flow back to the oil tank <NUM>.

Fuel oil is provided from the fuel oil air driven pump <NUM> to a fuel oil outlet 100f, and the oil pressure from the fuel oil air driven pump <NUM> can be read from a fuel oil pressure gauge <NUM>, while the oil pressure from the fuel oil air driven pump <NUM> can be released by a sealing oil pressure relief valve <NUM>, in which case released hydraulic oil will flow back to the oil tank <NUM>. A fuel oil pressure safety valve <NUM> is provided for protection of the fuel oil pressure gauge <NUM>. The fuel oil pressure safety valve <NUM> is adjusted to a maximum working pressure of <NUM> bar at the output side of the fuel oil air driven pump <NUM>. If the fuel oil pressure exceeds the <NUM> bar, the fuel oil safety valve <NUM> will open and hydraulic oil will flow back to the oil tank <NUM>.

<FIG> shows the diagram of the test system <NUM> described above in connection with <FIG>, which test system <NUM> holds the outlets for supply of sealing oil 100e, fuel oil 100f, and control oil or plunger oil 100d for a working test of the assembled injector valve <NUM> of <FIG>.

For this working test, the assembled injector valve <NUM> holding the valve body <NUM>, the plunger piston <NUM> and the top cover <NUM> is secured to the valve holder <NUM>, as illustrated and described in connection with <FIG>, where the valve holder <NUM> is connected to a spray chamber 5a with the nozzle <NUM> entering the spray chamber, whereby any hydraulic oil reaching out through the nozzle openings will be sprayed in the spray chamber 5a. The plunge oil inlet part 12a of the top cover <NUM> is supplied with hydraulic oil from the control oil outlet 100d, the sealing oil inlet port <NUM> of the top cover <NUM> is supplied with hydraulic oil from the sealing oil outlet 100e, and the fuel inlet 4a of the valve holder <NUM> is supplied with hydraulic oil from the fuel oil outlet 100f. The hydraulic oil supplied to the fuel inlet 4a is further supplied from the fuel inlet 4a to the first and second fuel inlet ports <NUM> and <NUM> of the valve body, as described in connection with <FIG>. For this test the control oil inlet port <NUM> is closed, and the supplied hydraulic oil will reach from the plunge oil inlet port 12a via the cover fluid channels 15a, 15b into the control oil channel <NUM>.

This test is performed using the test system <NUM> and test set-up as illustrated and described in connection with <FIG>. The purpose of this test is to verify that the suction valve <NUM> is tight by having the suction piston <NUM> fully closing the inputs to the fuel fluid channels <NUM>, see also <FIG>:.

If any gas bubbles are observed in in the liquid of the separate container 5c, the suction valve <NUM> is not completely tight. If no bubbles are observed, the suction valve <NUM> is tight.

The test of the suction valve <NUM> may further include the step of.

If an increased amount of test gas bubbles is observed when compared to the amount of test gas bubbles observed at the first test gas pressure of <NUM> bar, the suction valve (<NUM>) is open as required.

This test is performed using the test system <NUM> and test set-up as illustrated and described in connection with <FIG>. The purpose of this test is to verify that the nozzle valve <NUM> is tight by having the nozzle piston <NUM> fully closing the outputs from the fuel fluid channels <NUM>, see also <FIG> and <FIG>:.

If any test gas bubbles are observed a step <NUM>, the nozzle valve <NUM> is not completely tight. If no bubbles are observed, the nozzle valve <NUM> is tight.

This working test of the assembled injector valve <NUM> is not part of the invention and the working test is present for illustration purposes only.

This test is performed using the test system <NUM> and test set-up as illustrated and described in connection with <FIG>. The purpose of this test is to verify that the assembled injector valve <NUM> is operating as supposed to in normal operation mode. The injector valve <NUM> shall be assembled completely for this test. For this test the control oil inlet port <NUM> is closed, and the supplied hydraulic oil will reach from the plunge oil inlet port 12a via the cover chamber 12b into the plunger piston chamber <NUM> for providing a pressure on the plunger piston <NUM>, and from the plunge oil inlet port 12a via the cover fluid channels 15a, 15b into the control oil channel <NUM> for providing a pressure on the nozzle piston <NUM>.

If hydraulic oil sprays out from the nozzle openings <NUM> into the spray chamber at step <NUM>, then the valves <NUM>, <NUM>, <NUM> of the complete injector valve <NUM> are open as supposed to in normal operation mode.

The working test may further include a sealing test of the nozzle valve <NUM>:.

If hydraulic oil sprays out from the nozzle openings <NUM> into the spray chamber 5a, then the nozzle valve <NUM> is not completely tight. If no hydraulic oil is observed, the nozzle valve <NUM> is tight.

Claim 1:
A method of testing a valve body (<NUM>) of an injector valve (<NUM>) for a combustion engine, which valve body (<NUM>) holds
a plunger piston chamber (<NUM>) for forming a compression chamber (<NUM>), a suction valve (<NUM>) with a suction piston (<NUM>), one or more fuel fluid channels (<NUM>), a nozzle valve (<NUM>) with a nozzle piston (<NUM>), one or more nozzle openings (<NUM>), and a control oil channel (<NUM>), wherein the fuel fluid channels (<NUM>) provide a fluid connection from the plunger piston chamber (<NUM>) to the nozzle openings (<NUM>) when the suction valve (<NUM>) is open by a pressure on the suction piston (<NUM>) provided by a fluid pressure in the plunger piston chamber (<NUM>) and when the nozzle valve (<NUM>) is open by a pressure on the nozzle piston (<NUM>) provided by a control oil pressure supplied via the control oil channel (<NUM>); characterized in that the method comprises:
supplying control oil to the nozzle piston (<NUM>) via the control oil channel (<NUM>) at a first control oil pressure, said first control oil pressure being higher than or equal to a predetermined control oil opening pressure for which the nozzle valve (<NUM>) is configured to open;
supplying a test gas to the suction piston (<NUM>) via the plunger piston chamber (<NUM>) at a first test gas pressure being lower than a predetermined test gas opening pressure for which the suction valve (<NUM>) is configured to open; and
checking whether any of the supplied test gas is reaching out through the nozzle openings (<NUM>).