JPH08105371A - Method and equipment for measuring small fuel injection quantitty - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the measurement precision even of extremely small injection quantities of fuel by maintaining a constant return speed of a measuring piston and delaying changeovers of a solenoid valve. SOLUTION: While a measuring chamber 3 is exhausted again to a reference volume BV, the return speed of a measuring piston 5 is held practically constant, and the travel of the measuring piston 5 to be made in the changeover delay time of an electrically controlled valve 12 is estimated in consideration for the changeover delay obtained from the closing-motion characteristic curve of the valve 12, after which a predetermined changeover threshold, before the initial position of the measuring piston 5, triggers a changeover signal output to the solenoid valve 12 to close a pressure relief line 11 again by the solenoid valve 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a small fuel injection amount, in which the fuel injection amount is injected into a measurement chamber by a fuel injection valve during an injection process to increase the volume of the measurement chamber. Detected via a measuring piston, in this case
From the starting position corresponding to the reference volume of the measuring chamber to the end position corresponding to the measuring volume after the end of the injection process, from the starting position corresponding to the reference volume of the measuring chamber to the end position corresponding to the measuring volume, The injection amount is obtained from the difference from the measurement piston movement amount, and subsequently, after the measurement process, the measurement chamber is provided via a valve provided in the pressure relief line derived from the measurement chamber and electrically controlled by the movement of the measurement piston. Of the type which discharges to the reference volume again.

Further, the present invention is a measuring device for carrying out such a method, which is provided with a measuring chamber,
The measurement chamber is partitioned by one end surface of the measurement piston, and the measurement piston is movable in the cylinder against a constant returning force by the fuel injected into the measurement chamber, and the measurement piston moves. The quantity is adapted to be detected by a distance signal generator, a pressure relief line is derived from the measuring chamber, and an electrically controlled valve is provided in the pressure relief line, which valve , The pressure release line is opened after the end of fuel injection into the measurement chamber, and when the measurement piston reaches a prescribed position when the measurement piston returns, the pressure release line is closed again by a control signal activated by the measurement piston. About the format that is supposed to be done.

[0003]

2. Description of the Prior Art A method of this type and the associated device are known from DE-A 39 16 419. The known method and device do not take into account the switching delay of the controlled solenoid valve provided in the pressure relief line during readjustment of the reference volume of the measuring chamber. Due to this, the measurement results must accept the inaccuracy.

[0004]

SUMMARY OF THE INVENTION The object of the present invention is to improve the method of the type mentioned at the outset by providing a method in which the measuring accuracy is significantly increased even when measuring very small fuel injection quantities. is there.

A further object of the invention is to provide an advantageous measuring device for carrying out such a method.

[0006]

In order to solve this problem, in the method of the present invention, in the process of discharging the measuring chamber to the reference volume again, a substantially constant return speed of the measuring piston is maintained, and In consideration of the switching delay permissible on the basis of the closing motion characteristic curve of the valve controlled by the control valve, the distance traveled by the measuring piston within the time of the switching delay is taken into account and placed in front of the starting position of the measuring piston. At a switching threshold, a switching signal is sent to the electrically controlled valve for reclosing the pressure relief line by the electrically controlled valve.

Further, in order to solve the above-mentioned problems, in the structure of the measuring apparatus of the present invention, a pressure limiting valve is additionally provided in the pressure relief line in addition to the electrically controlled valve. .

[0008]

According to the present invention, the measurement accuracy is remarkably improved even when measuring a very small fuel injection amount. In the method according to the invention, the reference volume is maintained with high accuracy, since the return speed of the measuring piston can be kept constant and the switching delay of the solenoid valve can be determined. This requires little effort and no separate control unit is required to adjust this reference volume. This makes it possible to obtain a reproducible starting position of the measuring piston at each measurement and an accurate detection of each fuel injection quantity. In particular, fluctuations in the measurement result due to dynamic influences on the measurement result due to the return speed difference of the measuring piston are also avoided.

In an advantageous configuration according to the second aspect of the invention, if the specified displacement of the measuring piston cannot be exceeded during the injection process, then the return of the measuring piston is not carried out, but the individual injection processes are cumulatively performed. By sequentially performing the above, the measurement error at an extremely small fuel injection amount is reduced. In this case, in the configuration according to claim 3, the injection amount is continuously measured with respect to the moving distance of the measurement piston.
Volumetric as the difference between two jets.

In the structure of the measuring device according to the present invention as set forth in claim 4, the pressure release valve for releasing the pressure in the measurement chamber is provided with a pressure limiting valve in addition to the electrically controlled valve. , A constant return speed of the measuring piston is obtained.
In an advantageous configuration according to claim 6, the pressure limiting valve is
The valve member is exposed to the same pressure as the measuring piston as the return force. As a result, a constant differential pressure can be adjusted in the flow cross section of the pressure relief line by using a spring, so that the amount of outflow from the measuring chamber per unit time and thus the return speed of the measuring piston can be kept constant. can do.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

In order to measure a very small amount of fuel injected by the fuel injection valve 1, this fuel injection valve 1 is inserted into the measuring device 2 as shown in FIG. Such a fuel injection valve 1 is preferably a high-pressure injection valve used in a self-igniting internal combustion engine. This fuel injection valve 1
Is the minimum fuel injection amount, and the measuring chamber 3 formed in the measuring device 2
To inject. This measuring chamber 3 is formed as a closed cylinder 4 in the exemplary embodiment shown.
A measuring piston 5 is slidably arranged therein.
The end face 6 of this measuring piston 5 is located inside the cylinder 4 in the measuring chamber 3
Is partitioned. The back surface of the measuring piston 5 divides a gas filling chamber 7 filled with gas, and nitrogen under a constant pressure is supplied from the nitrogen reservoir tank 22 to the gas filling chamber 7. The pressure of the nitrogen gas is adjusted so that the measuring piston 5 can be displaced against the returning force of the nitrogen gas when the fuel is injected into the measuring chamber 3. The movement of the measuring piston 5 is detected by the distance signal generator 8. The distance signal generator 8 is connected to the contact pin 9 by the end face 6 of the measuring piston 5.
Is acting on the back side of. The fuel injection valve 1 is attached to a pipe piece 10 which communicates with the measurement chamber 3. A pressure relief line 11 is led out from the measurement chamber 3, and an electrically controlled valve, for example, a solenoid valve 12 is arranged in the pressure relief line 11. The solenoid valve 12 is a 2-port 2-position valve that opens and closes the flow passage of the pressure release pipe 11. The pressure relief line 11 continues to extend to the downstream side of the solenoid valve 12, and the pressure relief line 11 is provided with a pressure limiting valve 14. The pressure release pipe 11 communicates with the fuel outlet through the pressure limiting valve 14 without pressure.
The pressure limiting valve 14 has a movable wall in the form of a piston 16, which is guided in a bore 17 provided in a casing 18 of the pressure limiting valve 14. One of the pistons 16, that is, the first end surface 19 is adjacent to the pressure chamber 20 provided in the casing 18 of the pressure limiting valve 14. This pressure chamber 20 is connected via a supply line 21 to the same nitrogen reservoir tank 22 as the nitrogen reservoir tank that supplies the pressure applied to the back surface of the measuring piston 5.

The other end of the piston 16, that is, the second end face 24, partitions the inflow chamber 25. A supply pipe line 26 opens in the inflow chamber 25 in parallel with the axis of the hole 17. This supply line 26 is always connected to the pressure release line 11 that has entered the pressure limiting valve 14. An outflow passage 27 is led out on the side facing the second end face 24 coaxially with the axis of the hole 17. This outflow passage 27
The opening to the inflow chamber 25 is formed as a valve seat 28. This valve seat 28 cooperates with a ball 29 which acts as a valve member. The ball 29 is fixed to the second end surface 24 of the piston 16. In the range of the outflow passage 27, the plunger 31 is pressed against the valve member 29. The plunger 31 is closely guided at its rear end into the outflow passage 27. The back surface 33 of this plunger 31 is loaded by a spring 32 supported by the casing of the pressure limiting valve 14. Further, the back surface 33 of the plunger 31 is connected to the pressure release line 11 that has entered the pressure limiting valve 14. The plunger 31 holds the operating pin 34 on the side facing the valve member 29. The operating pin 34 opens an annular chamber with the outflow passage 27. This annular chamber is always connected laterally to the hole 35 led out from the outflow passage 27. This hole 35 is formed by the pressure relief line 11 extending continuously.
Is connected to the part. In this case, the pressure relief line 11 supplies the fuel derived from the pressure limiting valve 14 to the fuel reservoir tank without pressure.

Using the above measuring device, the fuel capacity can be enclosed in the measuring chamber 3 by means of the electromagnetic valve 12 which closes the pressure release line 11. The solenoid valve 12 takes such a position at the start of measurement of a small fuel injection amount. At this time,
The measuring piston 5 is in the starting position. In this starting position, the measuring piston 5 supplies a reference volume of fuel to the measuring chamber 3
It is enclosed inside. This starting position is fed back to the control device 36 via the distance signal generator 8. This control device 36 also serves to control the solenoid valve 12. The fuel in the measurement chamber 3 has a value defined by the nitrogen pressure in the gas filling chamber 7. In the illustrated embodiment, fuel is injected into the measurement chamber 3 via the fuel injection valve 1 by the fuel injection pump. At this time, an increase in volume occurs, and as a result,
The measuring piston 5 is moved. This measuring piston 5
The movement of is also detected by the distance signal generator 8.
The injection volume is calculated by the control device 36 and the connected computer from the volume difference obtained by subtracting the reference volume from the measurement volume measured at the end position of the measuring piston 5 after the injection process.

In order to adjust the same state for the next measuring process, the measuring piston 5 is returned to its starting position again after the end of the first measuring process. In this starting position, the measuring piston 5 also partitions the reference volume. This return of the measuring piston 5 is carried out by opening the pressure relief line 11 by means of a solenoid valve 12. The fuel flowing out at this time first flows into the pressure limiting valve 14 via the pressure release pipe 11. In the pressure limiting valve 14, the valve member 29 is located in the closed position under the action of the pressure in the pressure chamber 20. The pressure in the pressure chamber 20 applies a synthetic force to the piston 16 that is larger than the force transmitted to the piston 16 by the spring 32. By introducing the fuel into the inflow chamber 25, the piston 1
6 is additionally supplied by the second end face 24 from the inflow chamber 25, and this pressure also acts on the piston 16 via the rear face 33 of the plunger 31. The pressure flowing into the inflow chamber 25 is defined by the pressure in the gas filling chamber 7, while the same pressure as that formed in the gas filling chamber 7 also acts on the first end face 19 of the piston 16, so that the piston 1
6 is force-compensated for the fluid force acting on this piston 16. However, the spring force of the spring 32 acts on the piston 16 in addition. This spring 32, in combination with the pressure in the inflow chamber 25, can then lift the valve member 29 out of the valve seat 28 and allow the fuel to flow out into the bore 35 or into the relief line 11 which continues. Inflow chamber 2
When the pressure decreases due to the excessive fuel flow cross section in the valve seat 28 provided in FIG.
The closing force exerted on the piston 16 from the side of ∘ becomes dominant and the flow cross section is reduced. Thus, such a valve allows a constant pressure drop to be regulated in the flow cross section between the valve member 29 and the valve seat 28 of the pressure limiting valve. As a result of the constant amount of fuel flowing out per unit time, the measuring piston 5 is returned to the starting position at a constant speed.

The return of the measuring piston 5 is completed by the solenoid valve 12
By closing the. This means that when the defined position of the measuring piston 5 detected by the distance signal generator 8 is exceeded, a control signal is sent to the control device 36,
This is performed by operating the solenoid valve 12 via the control device 36. The mode of operation of the solenoid valve is clear from the diagram shown in FIG. In this diagram, curve A shows the movement of the measuring piston 5. Starting from the measured volume MV corresponding to the predetermined level reached, that is to say the end position of the measuring piston 5 after the injection process has taken place, the pressure relief line 11 is opened at time t1, so that the measuring piston 5 Corresponding to the inclination shown, returns to its starting position, that is to say the reference volume BV reached at time t2, at a substantially constant speed. At this position, the measuring piston 5 moves at time t
In the new measuring process at 3, the fuel remains until it is injected into the measuring chamber 3 again. When fuel is again injected into the measuring chamber 3 at time t3, the measuring piston 5 is displaced, with the result that the measuring piston 5 may possibly reach a predetermined end position with a slight overshoot. The measuring piston 5 is connected to the pressure relief line 1 before the introduction of a new measuring cycle.
It stays in the end position until it is returned to the starting position by opening 1.

Curve B shows the opening / closing process of the solenoid valve 12. The solenoid valve 12 is controlled by the voltage course in the solenoid valve 12 shown by curve C. As can be seen from the diagram of FIG. 2, when a voltage drop occurs in the solenoid valve 12 at time t0, the solenoid valve 12 first remains in the closed position and at time t1.
The first opening is started at. Such a time delay between the signal introduction and the actual movement of the closing member of the solenoid valve is well known, and such a time delay is caused by the movement of the closing member being acted upon by a spring. So it is constant.
Fuel can only flow into the pressure limiting valve 14 after the opening of the solenoid valve 12 has actually started. Solenoid valve 12
The rising edge at the instant t1 'of the voltage supply or the current supply to V.sub.2 also introduces a closing movement of the solenoid valve 12 after a certain delay time. Only when the time t2 is reached, the solenoid valve 12 is closed after a delay of time tE after the time t1 ′. At this point, the outflow of fuel through the relief line 11 is also completely interrupted and the measuring piston 5 is brought to a rest. For the above reasons, in order to return the measuring piston 5 to the desired level BV corresponding to the reference volume, the starting point for introducing the closing process of the solenoid valve 12 is located earlier by the time tE. There must be. However, this time corresponds to a fixed point in the movement of the measuring piston 5. The measuring piston 5 returns at a constant speed. In this way, a point in the return movement of the measuring piston 5 can easily be captured as a switching threshold, at which switching between the electrical actuation of the closing movement of the solenoid valve and the actual closing movement. Delay is taken into account. This makes it possible to easily obtain extremely accurate measurement results and very accurate maintenance of the starting position of the measuring piston 5.

The measuring device can detect a wide variety of small fuel injection amounts. However, in the case of very small injection quantities, for example in the range of fuel pre-injection for self-igniting internal combustion engines, the disadvantage is that due to the structural dimensions of the measuring piston, only very small movement steps are performed as displacement movements. Occurs. In this case, if an attempt is made to return to the starting position, a certain amount of error will occur, despite the constant return movement, i.e. the measured piston return speed, which can accordingly be kept small. . In such a case, the device according to the invention is adjusted in such a way that the return of the measuring piston to the starting position is only possible after the specified displacement of the measuring piston has been exceeded. Such an injection process performed with an extremely small fuel injection amount is first performed cumulatively until the required displacement of the measuring piston is performed. Such an individual injection quantity measurement can be detected as a measured piston position difference during the individual injection process. At this time, the position of the measuring piston at the end of the preceding injection is the reference volume, which is the reference volume. Such a process is shown in FIG.

In the case of the first embodiment shown in FIG. 1, the movable wall of the pressure limiting valve 14 is formed as the piston 16, but unlike the first embodiment, the second embodiment shown in FIG. In the example, this movable wall is formed as the diaphragm 116. This diaphragm 116 is a pressure limiting valve 11
First casing part 118a of the four casing 118
And the second casing portion 118b are tightly clamped and fixed. The movable wall formed as the diaphragm 116 surrounds the pressure chamber 20 already described in the first embodiment with one end face 119, as in the case of the first embodiment shown in FIG. This pressure chamber 20 still has a supply line 21.
It is connected to the nitrogen reservoir tank 22 via. The second end surface of the diaphragm 116 closes the inflow chamber 125 on the side opposite to the pressure chamber 20. The inflow chamber 125 is provided with a supply line 126 that extends parallel to the axis of symmetry of the valve body portion 40 that is cylindrically inserted into the second casing portion 118b. The end face of the valve body portion 40 partitions the other end of the inflow chamber 125. The other end of the supply line 126 is connected to the pressure release line portion 111a.
Further, the valve body portion 40 is provided with an outflow passage 127 as a through hole in the longitudinal axis of the valve body portion 40.
The opening of the outflow passage 127 to the inflow chamber 125 is formed as a valve seat 128. This valve seat 128 cooperates with a valve head 41 with a conically extending sealing surface which acts as a valve member. The valve head 41 is rigidly connected to the diaphragm 116 via a connecting member 42. The valve head 41 is moved to the guide shaft portion 43, and the guide shaft portion 43 together with the guide piston 44 is connected to the outflow passage 127.
It always rushes into the cylindrical hole. Further, the guide shaft portion 43 forms an annular chamber 45 together with the outflow passage 27 between the guide shaft portion 43 and the sealing surface provided on the valve head 41. The annular chamber 45 has a pressure release conduit portion 111 that is branched from the outflow passage 127 in the range of the annular chamber 45.
Always connected to b. A back surface 133 of the guide piston 44 on the side opposite to the valve head 41 is provided with an electromagnetic valve 12 through an opening of an outflow passage 127 that advances from the valve body portion 40.
Is connected to a pressure release conduit portion 111a extending from the. The pressure release conduit portion 111 a is also connected to the inflow chamber 25 via the supply conduit 126.

Such a structure has the following advantages. That is, the piston 16 of the first embodiment shown in FIG.
It is no longer necessary to consider the extra mobility of the and the sealing properties that must be maintained against the gas cushion. This is because the diaphragm 116 is highly movable with less hysteresis, and at the same time, the diaphragm 1
This is because 16 ensures a perfect isolation between the pressure chamber 20 and the inflow chamber 125. The guide of the valve member including the valve head 41 and the guide shaft portion 43 is received by the outflow passage 127 provided as a guide hole. In this connection, an auxiliary spring, such as the spring 32 used in the first embodiment shown in FIG. 1, can be dispensed with, owing to the low friction guide obtained. In other respects, the working form of this pressure limiting valve is the same as that of the first embodiment shown in FIG.

In order to obtain a particularly accurate measurement result, FIG.
The measuring piston 5 used in the first embodiment shown in FIG. 1 must be designed particularly simply, and is preferably designed as a very thin pot-shaped piston. On the other hand, the measurement results are also influenced by the effect of friction on the piston guide. For this, this guide must be lubricated. This is preferably done via leaking fuel from the measuring chamber. In this regard, diesel fuels in particular have lubricating properties.
However, in order to prevent the leaked fuel from flowing into the gas filling chamber 7, it is necessary to provide a leak groove in the wall of the cylinder that guides the piston. This is shown in FIG. In the embodiment shown in FIG. 5, the end face of the measuring piston 105, which is formed thin as described above, also partitions the measuring chamber 103 inside the cylinder 104. Fuel is introduced into the measurement chamber 103 by the fuel injection valve 101. This fuel can be led out again via the pressure relief line 111 under the control of an electrically controlled valve 112 as in the first embodiment shown in FIG. The leak groove is the measuring piston 1 of the cylinder 104.
It is provided as an annular groove 47 in the area which is always covered by the thin outer peripheral wall 05 of 05, and thus forms a closed annular chamber. This annular chamber 47 has a pressure relief line portion 211a extending from the electrically controlled valve 112.
Connected through. The other end of this pressure relief line is led out of the annular chamber 47 and opens into the pressure limiting valve 14; 114. Therefore, the annular chamber 47 is flowed through by the fuel whose output is controlled by the electrically controlled valve 112, and the thin outer peripheral wall 48 corresponds to the nitrogen pressure formed in the gas filling chamber 7 in the range of this groove. Loaded by fuel pressure. In this way, the thin outer peripheral wall of the piston is prevented from being deformed in the area of the annular chamber 47. Such a deformation can lead to a failure of the measuring piston or at least a deterioration of its mobility. Moreover, the lubrication of the piston may be impaired. With such means, leaking fuel can escape via the annular chamber 47, so that a satisfactory separation of the gas and fuel components is obtained. In addition, the annular chamber 47, which may occur when the annular chamber 47 is unpressurized,
The inflow of nitrogen into is also avoided. If nitrogen flows into the annular chamber 47, at least the piston outer peripheral wall region at the lower end portion is dried by the nitrogen flow, and the sliding characteristics of the piston may be significantly reduced. These disadvantages are largely prevented by the measures according to the invention.

[Brief description of drawings]

1 is a schematic view of a first embodiment of the device according to the invention for carrying out the method according to the invention.

2 is a diagram showing the relationship between the temporal movement of the measuring piston and the corresponding solenoid valve control and valve member movement.

FIG. 3 is a diagram showing the movement of a measuring piston in the case of measuring an extremely small fuel injection amount in relation to time.

4 is a cross-sectional view showing another embodiment of the pressure limiting valve shown in FIG.

5 is a schematic view showing still another embodiment of the measuring apparatus shown in FIG.

[Explanation of symbols]

1 fuel injection valve, 2 measuring device, 3 measuring chamber, 4
Cylinder, 5 Measuring piston, 6 End face, 7
Gas filling chamber, 8 distance signal generator, 9 contact pin, 10 tube piece, 11 pressure release line, 12 solenoid valve, 14 pressure limiting valve, 16 piston, 17
Hole, 18 casing, 19 first end face, 20
Pressure chamber, 21 supply line, 22 nitrogen reservoir tank, 24 second end face, 25 inflow chamber, 26 supply line, 27 outflow passage, 28 valve seat, 29 ball, 31 plunger, 32 spring, 33 back surface, 34 actuation Pin, 35 hole, 36 control device, 40 valve body part, 41 valve head, 42 coupling member, 43 guide shaft part, 44 guide piston,
45 annular chamber, 47 annular groove, 48 outer peripheral wall,
101 Fuel Injection Valve, 103 Measuring Chamber, 104 Cylinder, 105 Measuring Piston, 111 Pressure Release Pipeline, 111a Pressure Release Pipeline Part, 111b Pressure Release Pipeline Part, 112 Valve, 114 Pressure Limiting Valve, 116
Diaphragm, 118 casing, 118a,
118b casing part, 119 end face, 125
Inflow chamber, 126 supply pipeline, 127 outflow passage,
128 valve seat, 133 rear surface, 211a pressure relief pipe line portion

Front page continued (72) Inventor Henri Pajano France Vanish Ryu Jean Duclos 43 (72) Inventor Philip Puri France Maranne Le Clos de Mouriel (No address) (72) Inventor Bernard Ramon France Saint-Juice Chalet Piro (No house number) (72) Inventor Maurice Tivui, France, Mejuu Ryu De Lorraine 11

Claims (16)

[Claims] 1. A method for measuring a small fuel injection amount, which comprises injecting the fuel injection amount into a measuring chamber (3) by a fuel injection valve during an injection process, and increasing the volume of the measuring chamber (3). Is detected via the measuring piston (5), in which case the measuring piston (5) is referenced to the reference volume (BV) of the measuring chamber (3).
Between the reference volume (BV) and the measurement volume (MV) from a starting position, which corresponds to, to a terminal position, which corresponds to the measurement volume (MV) after the end of the injection process, against a constant return force. The injection amount is determined from the difference from the measured piston movement amount, and subsequently, after the measurement process, it is electrically controlled by the movement of the measuring piston (5) provided in the pressure release conduit (11) derived from the measuring chamber (3). In the type in which the measurement chamber (3) is again discharged to the reference volume (BV) through the valve (12) to be discharged, in the process of discharging the measurement chamber (3) to the reference volume (BV) again, Maintaining a substantially constant return speed of the measuring piston (5) and taking into account the switching delay observed on the basis of the closing motion characteristic curve of the electrically controlled valve (12), which progresses within the time of the switching delay. Enter the movement distance of the measuring piston (5) A switching signal for reclosing the pressure relief line (11) by means of the electrically controlled valve (12) at a switching threshold pre-positioned in the starting position of the measuring piston (5). A method for measuring a small fuel injection quantity, characterized in that it is delivered to a valve which is controlled by a valve. 2. A plurality of injection processes or a plurality of injection processes in which the re-emissions of the measuring chamber (3) are cumulatively summed to achieve a specified travel distance from the starting position of the measuring piston (5). The method of claim 1 which is performed only after the injection series. 3. An injection series consisting of a plurality of injection strokes in which the specified travel distance of the measuring piston (5) has not been achieved even with cumulative summing, each of which is preceded by a measuring piston (5). The position achieved after the injection process,
The method according to claim 2, which is used as a reference volume for determining an injection volume. 4. A measuring device for carrying out the method according to claim 1, wherein a measuring chamber (3) is provided and the measuring chamber (3) is a measuring piston. It is partitioned by one end face (6) of (5),
The measuring piston (5) is movable in the cylinder (4) against the constant return force by the fuel injected into the measuring chamber (3), and the moving amount of the measuring piston (5) is the distance. It is designed to be detected by a signal generator (8), a pressure relief conduit (11) is led out from the measurement chamber (3), and a valve (electrically controlled to the pressure relief conduit (11) ( 1
2) is provided by means of the valve (12) after the fuel injection into the measuring chamber (3) has ended.
Is released and when the measuring piston (5) reaches a defined position when the measuring piston (5) returns, the pressure relief line (11) is closed again by a control signal triggered by the measuring piston (5). In this type, a pressure limiting valve (14) is arranged in the pressure relief line (11) in addition to the electrically controlled valve (12). Measuring device for measuring small fuel injection quantity. 5. Measuring device according to claim 4, wherein the pressure limiting valve (14) is arranged downstream of the electrically controlled valve (12) formed as a solenoid valve. 6. The measuring piston (5) is loaded by a constant fluid pressure and the pressure limiting valve (14) has a movable wall (16), which wall (16) At the first end face (19) of said constant fluid pressure and at the other second end face (24) of said electrically controlled valve (12) downstream of said relief line. It is loaded by the pressure in the (11) and the spring force of the spring (32), and receives the action of the spring (32) and the action of the pressure on the second end face (24) to move the movable member. 6. Measuring device according to claim 4 or 5, characterized in that the valve member (29) movable by the wall (16) is movable from the closed position. 7. The movable wall (16) is formed as a cylindrical piston (16) guided in a casing (18) of the pressure limiting valve (14), the piston (16) The second end face (24) is connected to the pressure limiting valve (1
4) partitioning the inflow chamber (25) connected to the pressure release pipe line (11) located upstream of the valve member (2).
9) is connected to the second end face (24) of the piston (16), and further the valve member (29) rushes into the inflow chamber (25) and opens at this location. 7. Measuring device according to claim 6, cooperating with a valve seat (28) provided on the (27). 8. A spring (32) for loading said piston (16) acts on said piston (16) via a plunger (31) guided over an extension of said outflow passage (27). The measuring device according to claim 7. 9. The back surface of the plunger (31) is also provided with the pressure relief conduit (1) upstream of the pressure limiting valve (14).
9. The measuring device according to claim 8, which is exposed to the pressure in 1). 10. The measuring device according to claim 9, wherein the valve member (29) is provided with a ball pressed into the piston (16) and press-fitted. 11. The pressure limiting valve (1) having the movable wall.
14) is formed as a diaphragm (116) clamped to the casing (118a, 118b) of the diaphragm (116), and the second end face (124) of the diaphragm (116) has the pressure limiting valve (124) of the pressure relief line. 114) partitioning an inflow chamber (125) connected to a portion (111a) located on the upstream side, and the valve member (129) is coupled to the second end surface (124) of the diaphragm (116). In addition, the valve member (129) is connected to the inflow chamber (12).
5) The outflow passage (12
7) Cooperating with a valve seat (128) provided in 7).
The measuring device described. 12. The valve member (129) comprises a valve head (41) with a guide shaft (43), the valve head (41) being followed by the guide shaft (43). It has an annular groove, and the other end of the annular groove is partitioned by a guide piston (44) provided in the guide shaft portion (43), and the annular chamber (with the outflow passageway (127) ( 45), and the annular chamber (45) is always connected to a portion (111b) of the pressure relief pipe, which is led out from the inner wall of the outflow passage (127), and the valve head (41). ) Is connected to the diaphragm (116) via a connecting portion (42), the valve head (4)
12. The measuring device according to claim 11, wherein a sealing surface provided in 1) controls the outflow passage (127). 13. A portion (11) of the guide shaft portion (43) on the side opposite to the valve head (41) on the upstream side of the pressure limiting valve (114) also in the pressure release line.
The measuring device according to claim 12, which is exposed to the pressure in 1a). 14. A measuring piston (105) is formed as a pot-shaped piston having a thin peripheral wall (48), the bottom face of the piston facing outwards being the end face. 7. Measuring device according to claim 6, characterized in that it partitions the (103), a distance signal generator (8) is frictionally connected to the inner bottom surface of the piston and is loaded by fluid pressure. 15. An annular groove (47) in the wall of the cylinder (104) in which the measuring piston (105) is guided.
And said annular groove (47) forms an annular chamber with said measuring piston (105), said annular chamber comprising said electrically controlled valve (1) of said relief line.
15. The measuring device according to claim 14, which is always connected to the portion (211a) located on the upstream side of 2). 16. The annular chamber (47) is located in the pressure relief conduit section (211a) between the electrically controlled valve (12) and the pressure limiting valve (114). 16. The measuring device according to claim 15, wherein