JPH04339139A - Electronically controlled gasoline injection pump and its control method - Google Patents

Abstract

PURPOSE:To carry out fuel injection without applying an engine rotating signal at its starting in an electronically controlled gasoline injection pump using a piezoelectric component. CONSTITUTION:Voltage is applied to a piezo laminated body 17 for its extension, and pressure in a transformation chamber 26 therefore rises to press a valve needle 22 onto a seat 34 for blocking up an overflow passage 35. The transformation chamber 26 communicates with a pressure chamber 6 through a communicating passage 33, and repeatedly closes and opens at every cycle according to the rotation of a plunger 3. When the voltage is cyclically applied to the piezo laminated body 17, the pressure in the transformation chamber 26 becomes different during the closing and opening of the passage 33 to change the terminal voltage of the piezo laminated body 17. This voltage variation is detected to detect the closing or opening of the passage 33 for carrying out fuel injection 7.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to an electronically controlled fuel injection pump that controls fuel injection start timing, injection amount, injection rate, etc. by controlling the voltage applied to a piezoelectric body, and more specifically, the present invention relates to an electronically controlled fuel injection pump that controls fuel injection start timing, injection amount, injection rate, etc. by controlling the voltage applied to a piezoelectric body. The present invention relates to an improved structure of an electronically controlled fuel injection pump and a control method thereof to improve performance.

0002

2. Description of the Related Art In internal combustion engines, especially diesel engines, there is a demand for improved accuracy in fuel injection control in order to improve exhaust gas properties and improve engine performance. For this reason, fuel injection pumps have conventionally been devised that use solenoid-driven electromagnetic spill valves to open and close overflow passages during the pressurizing stroke of the plunger to control fuel injection timing and injection amount. However, in recent years, the speed of diesel engines has increased,
Due to the trend of increasing the number of cylinders, it is necessary to further improve the accuracy of fuel injection control, and a control device having higher responsiveness than that of an electromagnetic spill valve is now required. Therefore,
Electronic control with excellent responsiveness that uses a piezoelectric material with high responsiveness to change the volume of the variable pressure chamber, and opens and closes the overflow passage by driving the valve body of the spill valve based on changes in fluid pressure within the variable pressure chamber. A fuel injection pump has been developed. (Unexamined Japanese Patent Publication No. 63
-065132)

0003

In the electronically controlled fuel injection pump described above, characteristics such as fuel injection start timing, injection amount, injection rate, etc. are determined by controlling the voltage application timing to the piezoelectric body. A reference position signal and a rotation angle signal for controlling the voltage application timing are given as a rotation signal (NE pulse signal) of a pump drive shaft that rotates synchronously with the crankshaft.

However, since this NE pulse signal uses an electromagnetic induction type proximity switch that uses a magnetic pickup to detect the convex teeth of a gear mounted on a rotating shaft,
When the rotation speed is low, the sensitivity of the pickup becomes low,
The minimum rotation speed that can practically detect the NE pulse signal is 150.
It is about rpm. On the other hand, when starting an engine at extremely low temperatures (e.g. below -25°C), the friction in various parts of the engine increases due to increased viscosity of the lubricating oil, and the cranking speed may drop below 150 rpm. be. In such a case, the above-mentioned NE pulse is not generated, so that a problem arises in which the electronically controlled fuel injection pump becomes unable to control the fuel injection.

In other words, in such a case, a conventional fuel injection pump using a solenoid type spill valve injects the entire amount of fuel by constantly energizing the solenoid and keeping the spill valve closed, thereby improving engine startability. is ensured. However, in an electronically controlled fuel injection pump using a piezoelectric body such as that disclosed in Japanese Patent Application Laid-Open No. 63-065312, the variable pressure chamber that generates the fluid pressure for controlling the opening and closing of the spill valve is transferred to the low pressure chamber via the pressure chamber in each cycle. Therefore, even if voltage is kept applied to the piezoelectric body and the pressure in the variable voltage chamber is maintained high, the pressure in the variable voltage chamber is reset every cycle (becomes equal to the pressure in the low pressure chamber). Since the spill valve will open, fuel injection will not be possible.

As mentioned above, electronically controlled fuel injection pumps have the problem of not being able to ensure starting of the engine at extremely low temperatures, which is one of the major reasons for preventing their practical use. SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide an improved structure of an electronically controlled fuel injection pump and a control method thereof, which enable fuel injection even when no NE pulse signal is input.

[0007]

[Means for Solving the Problems] According to the present invention, there is provided a reciprocating plunger that pressurizes fuel in a pressure chamber formed in a cylinder, and an injection fuel passage that supplies pressurized fuel in the pressure chamber to a fuel injection valve. , an overflow passage that communicates the pressure chamber with a low pressure chamber at a predetermined pressure outside the cylinder, a valve body that opens and closes the overflow passage, a piezoelectric body that expands and contracts in accordance with the application of voltage, and an expansion and contraction of the piezoelectric body. a variable pressure chamber that generates a fluid pressure that drives the valve body to open and close according to the pressure, and a switching means that closes an introduction passage communicating between the variable pressure chamber and the low pressure chamber during a pressurizing stroke of the plunger, the switching device In a fuel injection pump that controls fuel injection by controlling the voltage applied to the piezoelectric body while the introduction passage is closed, when the pressure in the variable pressure chamber becomes lower than the pressure in the low pressure chamber, An electronically controlled fuel injection pump is provided, characterized in that the electronically controlled fuel injection pump is provided with means for allowing fuel to flow into the variable pressure chamber.

Furthermore, according to the present invention, the above-mentioned electronic device is characterized in that the voltage applied to the piezoelectric body is controlled by detecting the closing or opening of the introduction passage from a change in the voltage applied to the piezoelectric body. A method of controlling a controlled fuel injection pump is provided.

[0009]

[Operation] When the introduction passage is open, the pressure inside the variable voltage chamber is the same as that in the low pressure chamber, and even if the piezoelectric body expands, the pressure inside the variable voltage chamber does not increase. On the other hand, when the introduction passage is closed, the transformation chamber is in a sealed state, so when the piezoelectric body is expanded, the pressure inside the transformation chamber increases significantly, and a large reaction force is applied to the piezoelectric body. Therefore, if a voltage is applied to the piezoelectric body when the introduction passage is closed, a higher terminal voltage will be obtained when the introduction passage is opened, and by determining this voltage, it is possible to detect whether the introduction passage is actually open. can.

However, if a voltage is applied to the piezoelectric body when the introduction passage is opened, and then the introduction passage is closed while the voltage is being applied, the pressure inside the transformer chamber does not change, so the terminal voltage also does not change. Unable to detect closure of introduction passage. Also,
Even if the voltage applied to the piezoelectric body is released from this state and the voltage is applied again, the pressure inside the transformation chamber will only become negative pressure and then return to the original pressure (same pressure as the low pressure chamber), and the terminal Voltage does not rise.

In the present invention, a means is provided for allowing fuel to flow from the low pressure chamber to the variable pressure chamber when the pressure in the variable pressure chamber becomes lower than the pressure in the low pressure chamber, so the pressure in the variable pressure chamber remains unchanged even after the voltage is removed. It is maintained at the same level as a low pressure chamber. Therefore, when voltage is applied again, the pressure inside the variable voltage chamber increases significantly and the terminal voltage of the piezoelectric body changes, so that closure of the introduction passage can be detected. Further, when the introduction passage is opened while voltage is being applied to the piezoelectric body, the pressure in the voltage transformation chamber decreases and the terminal voltage of the piezoelectric body decreases, so that opening of the introduction passage can be detected.

Therefore, applying and releasing voltage to the piezoelectric body is periodically repeated, and if the terminal voltage of the piezoelectric body rises by a predetermined value while voltage is being applied, the voltage is held without being released, and the voltage is increased from that state. When the voltage decreases by a predetermined value, the pressure in the variable voltage chamber can be maintained at a high level while the introduction passage is closed by releasing the voltage. Therefore, the spill valve can be kept closed during the compression stroke of the plunger, and the full amount of fuel can be injected like a solenoid-driven spill valve.

[0013]

[Embodiment] Next, an embodiment of the present invention will be described using FIGS. 1 to 4. FIG. 1 is a longitudinal sectional view showing the configuration of this embodiment. In FIG. 1, a fuel injection pump 1 of this embodiment is a distribution type pump, and a plunger 3 slidably supported in a cylinder bore 2 is driven by an engine (not shown).
Rotational reciprocating motion is performed in synchronization with a rotation speed that is one-half of the engine rotation speed. The plunger 3 has one distribution port 4 and the same number of intake grooves 5 as the number of engine cylinders on its outer circumference.
A pressure chamber 6 is formed between the tip surface of the plunger 3, the cylinder bore 2, and the blind stopper 15.

The cylinder 7 and the casing 8 are formed with an intake passage 10 that communicates the low pressure chamber 9 and the cylinder bore 2, and a distribution passage 12 that allows each external injection valve 11 to communicate with the cylinder bore 2. The same number of distribution passages 12 as the number of engine cylinders are provided, and a delivery valve 13 is provided in each of the distribution passages 12 in the middle. The delivery valve 13 can be opened against the force of the spring 14, and has a function as a check valve and a suction valve. Therefore, when the plunger 3 moves to the left in the figure and the pressure chamber 6 expands, that is, during the suction stroke, one of the suction grooves 5 is connected to the suction passage 1.
0, the fuel in the low pressure chamber 9 is sucked into the pressure chamber 6,
On the contrary, when the plunger 3 moves to the right in the figure and the pressure chamber 6 is compressed, that is, during the compression stroke, the distribution port 4 is communicated with one of the distribution passages 12 and the pressurized fuel in the pressure chamber 6 is connected. is discharged to the outside. Note that the time when the plunger 3 starts to move to the right is sufficiently earlier than the time when the injection valve 11 is requested to start injection, and the time when the plunger 3 stops moving to the right is when the injection valve 11 is requested to stop injection. It is fixed to be sufficiently later than the period.

The casing 8 of the fuel injection pump 1 is provided with a pressure control valve 16 for controlling the pressure in the pressure chamber 6. The pressure control valve 16 controls the fuel injection start timing, injection amount, and The injection rate is controlled. The pressure control valve 16 includes a piezo layered body 17 that is a piezoelectric body that expands and contracts in response to the application of voltage, a piston 18 that is displaced in response to the expansion and contraction of the piezo layered body 17, and the piston 18 attached upward in the figure. the disc spring 19 that urges the piezoelectric laminate 17;
, a piezo housing 20 that houses a piston 18, a disc spring 19, a cap housing 21, a valve needle 22, a spring 23 that always biases the valve needle 22 in the valve opening direction, and a valve needle 22 and a spring 23. It consists of a valve housing 24.

The valve housing 24 is prevented from rotating by a knock pin 25, and the pressure control valve 16 is screwed onto the casing 8. The disc spring 19 is disposed between the piston 18 and the piezo housing 20, and a variable pressure chamber 26 is formed therein to maintain pressure for biasing the valve needle 22 in the valve closing direction. The outer periphery of the piston 18 is provided with oxygen to prevent the pressure inside the variable pressure chamber 26 from leaking.
A ring 27 is provided.

The piezo laminate 17 includes a disc-shaped PZT element with a diameter of 15 mm and a thickness of 0.5 mm, and a PZT element with a diameter of 15 mm and a thickness of 0.5 mm.
Copper plates each having a thickness of 0.1 mm are laminated alternately to form a disc shape, and the lead wires 28 and the copper plates are connected so that a voltage can be applied in parallel in the thickness direction of each PZT element. The lead wire 28 extends to the outside of the piezo housing 20 via a grommet 29 and is connected to a drive circuit 200.

[0018] The PZT element is a fired ferroelectric ceramic mainly composed of lead zirconate titanate.
This is a typical element that has a piezoelectric effect. Its physical properties are that when a voltage of 500 V is applied in the thickness direction, the thickness increases by 0.5 μm, and conversely, when a voltage of 500 V is generated and the voltage is shorted, the thickness decreases by 0.5 μm, and the thickness increases by 200 kg in the thickness direction. When a pressure of /cm2 is applied, a voltage of 200 V is generated in the thickness direction. In this embodiment, the piezo stack 17 is made by stacking 100 PZT elements and electrically connecting them in parallel, and when a voltage of 500 V is applied, an elongation of 50 μm is obtained.

The piston 18, which is biased upward in the figure by the disk spring 19, slides within the piezo housing 20 in response to the expansion and contraction of the piezo laminate 17, thereby varying the volume of the variable pressure chamber 26. The valve needle 22 is slidably disposed within the valve housing 24, and a spring chamber 30 is formed on the casing 8 side of the valve needle 22. Further, a spring 23 is inserted into the spring chamber 30 to always bias the valve needle 22 in the valve opening direction, and this spring chamber 30 is electrically connected to the low pressure chamber 9 through a passage 31 bored in the casing 8. ing.

Further, the variable pressure chamber 26 communicates with the cylinder bore 2 via a communication passage 33. After the suction stroke ends and before the plunger 3 enters the compression stroke, the communication passage 33 is cut off from the pressure chamber 6 by the rotation of the plunger 3, and similarly, when the compression stroke of the plunger 3 ends and the plunger 3 enters the suction stroke, Thereafter, the communication passage 33 communicates with the pressure chamber 6 via the suction groove 5 by rotation of the plunger 3.

Above the valve needle 22 in the figure, there is a variable pressure chamber passage 32 bored in the piezo housing 30.
During the compression stroke (when the communication passage 33 and the pressure chamber 6 are blocked), the piezo laminate 17 expands, the volume of the variable pressure chamber 26 decreases, and when the pressure in the variable pressure chamber increases, the valve needle 22 seats on the seat surface 34. Pressure chamber passage 3 leading to pressure chamber 6
5 and the spring chamber 30 are cut off.

Furthermore, in the present invention, a check valve 36 is provided between the communication passage 33 communicating with the variable pressure chamber 26 and the low pressure chamber 9, so that the pressure in the variable pressure chamber 26 is lower than the low pressure chamber 9 by a predetermined value (
In this embodiment, when the pressure becomes lower than 0.2 kg/cm2), the check valve 36 opens and the fuel in the low pressure chamber 9 flows into the variable pressure chamber 26. When the pressure difference falls below the predetermined value, the check valve 36 closes. Conversely, when the pressure in the variable pressure chamber 26 is higher than the pressure in the low pressure chamber 9, the check valve 36 remains closed and the pressure in the variable pressure chamber 26 decreases. It will remain as it is.

Next, the drive circuit 200 will be explained. FIG. 2 is a circuit diagram showing details of the drive circuit 200 in FIG. 1. Reference numeral 101 is, for example, a 12V on-vehicle battery, and power supplied from this battery 101 is connected to a primary coil 202 of an iron core transformer 201 made of, for example, a large number of laminated silicon steel plates. The other end of the primary coil 202 is connected to the collector of the transistor 203, and the constant current control circuit 204 controls the transistor 203.
The base current of the primary coil 202 is controlled, and the current flowing through the primary coil 202 is controlled. The emitter of the transistor 203 is grounded via a resistor 205.
The constant current control circuit 20 controls the voltage on the transistor 203 side.
4 and monitors the current value flowing through the primary coil 202.

The transformer 201 has a secondary coil 208
is wound. Primary coil 202 and secondary coil 2
The number of turns ratio of 08 is determined in consideration of the voltage generated on the secondary side, the rise time of the secondary voltage, etc., and in this embodiment, the number of turns is approximately twice that of the primary side. The piezo stack 17 is connected to one end of the secondary coil 208, and the other end is connected to the cathode of the diode 206 and the transistor 207.
connected to the collector. Therefore, when short-circuiting the piezo stack 17, the transistor 207 is turned on, and a circuit is formed with the piezo stack 17, the secondary coil 208, and the transistor 207.

Transistor 203, transistor 20
The base current of 7 is controlled by an electronic control unit (ECU) 102. As is well known, the ECU 102 is a digital computer that includes a CPU, RAM, and ROM.
, an AD converter, an input port, an output port, etc. The control routine program is stored in the ROM of the ECU 102, and the N
E-pulse signal, water temperature, accelerator opening, piezo laminate 17
Depending on the voltage of the transistor 207, a dwell signal and a current value signal are output to the constant current control circuit 204, and a short signal is output to the base of the transistor 207.

FIG. 3 is an explanatory diagram of the operation of the drive circuit 200 based on the passage of time. As shown in FIG. 3(a), when the dwell signal is turned on, energization of the primary coil 202 begins. The current flowing through the primary coil 202 gradually increases and reaches the current value Ip(A) indicated by the current value signal after 2 ms (FIG. 3(b)), and that current value Ip is maintained by the constant current control circuit 204. be done. In other words, the ON time of the dwell signal needs to be at least 2 ms.

As shown in FIG. 3(c), the dwell signal is
When F is applied, the magnetic energy stored in the transformer 201 is injected into the piezo stack 17 at once, applying a voltage to the piezo stack 17 and causing it to expand. In this case, the terminal voltage of the piezo stack 17 is equal to the current value Ip and the piezo stack 1
It is determined by the load applied to 7. Then, Fig. 3 (d
), the short signal is connected to the transistor 207.
When the voltage is input to the base of the piezo layer 17, the voltage of the piezo layered body 17 is short-circuited (released) and contracts. Note that the reason why the voltage of the piezo stack 17 suddenly becomes high in FIG. 3(c) is due to the load that the piezo stack 17 receives when it expands and moves the piston 18.

Next, the operation of this embodiment will be explained using FIGS. 1 and 4. FIG. 4 is an operation explanatory diagram showing the movement of each part over time in this embodiment. During the suction stroke of the plunger 3, the suction groove 5 of the plunger 3 communicates via the suction passage 10 with a low pressure chamber 9 to which pressurized fuel is supplied from a feed pump (not shown). As it moves to the left, fuel in the low pressure chamber 9 is sucked into the pressure chamber 6. Here, the suction groove 5 which is in communication with the suction passage 10 and another suction groove 5 located at a position shifted by 180 degrees are in communication with the communication passage 33, and the pressure change chamber 26
As shown in FIG. 4, the pressure is the same as that of the low pressure chamber 9 (5 kg/cm2 in this embodiment).

At this time, as shown in FIG. 4, the dwell signal and short signal are turned on, for example, every 20 ms (50 Hz).
Then, the application of voltage to the piezo stack 17 and short-circuiting are repeated. At this time, the voltage application time to the piezo stack 17 is 10 ms, and the piezo stack 1
7 voltage is input to the ECU 102 (FIG. 4(a)). When the communication passage 33 is open and the pressure chamber 6 and the variable pressure chamber 26 are electrically connected, the piezo laminate 17 expands and the variable pressure chamber 2
Even if the volume of the variable pressure chamber 26 is reduced, the pressure in the variable pressure chamber 26 is maintained at the same pressure as the low pressure chamber 9 (5 kg/cm2).

Thereafter, as shown in FIG. 4(b), the communication between the suction passage 10 and the pressure chamber 6 is cut off by the rotation of the plunger 3, and the communication between the communication passage 33 and the pressure chamber 6 is also cut off. . At this time, if a voltage is being applied to the piezo stack 17, then the voltage of the piezo stack 17 is short-circuited, and when the volume of the voltage change chamber 26 becomes smaller, the voltage change chamber 26
Since the pressure in the low pressure chamber 6 is lower than that in the low pressure chamber 9, the check valve 36 opens as shown in FIG. 4(c), and the fuel in the low pressure chamber 9 flows into the variable pressure chamber 26 through the communication passage 33. When the pressure difference reaches the set pressure of the check valve (0.2 kg/cm2), check valve 3
6 closes the valve.

As shown in FIG. 4(d), when the communication passage 33 is closed and the pressure chamber 6 and the variable pressure chamber 26 are cut off, the piezo laminate 17 expands to increase the volume of the variable pressure chamber 26. As the pressure decreases, the pressure increases, and in this example, the pressure in the variable pressure chamber 2
The pressure inside 6 rises to 70 kg/cm2. Therefore, the valve needle 22 is seated on the seat surface 34, and communication between the pressure chamber passage 35 communicating with the pressure chamber 6 and the spring chamber 30 is cut off. At this time, the piston 18 receives pressure from the variable pressure chamber 26, but in this embodiment, the area ratio of the piston 18 and the piezo laminate 17 is 1:2.5, and the piezo laminate 17 has an area of 70 kg/cm2 x 2. .5 = 175kg
It is subjected to pressure due to a reaction force of /cm2. Communication passage 33
When the is open, the pressure inside the variable pressure chamber 26 is 5 kg/c.
m2, the pressure applied to the piezo laminate 17 is 5k.
g/cm2 x 2.5 = 12.5 kg/cm2. Therefore, the terminal voltage of the piezo laminate 17 is
When closed, the above pressure difference (175 -12
．． 5=162.5kg/cm2) (approximately 1
60 V).

The ECU 102 determines that the communication passage 33 is in the closed state based on the voltage input to the ECU 102 5 ms after the voltage is applied to the piezo stack 17. When the communication passage 33 is in the closed state, the ECU 102 does not output a short signal, the voltage of the piezo stack 17 is maintained as it is, and the pressure of the variable voltage chamber 26 is also maintained. Thereafter, the compression stroke of the plunger 3 begins, and the pressure in the pressure chamber 6 increases as the plunger 3 moves to the right, and when it reaches 160 kg/cm2, which is the opening pressure of the injection valve 11, injection begins. Thereafter, the plunger 3 continues to move to the right, and as it moves to the right, the pressure in the pressure chamber 6 further increases.

As shown in FIG. 4(e), when the suction passage 10 and the pressure chamber 6 are brought into communication by the rotation of the plunger 3, the pressure in the pressure chamber 6 becomes 5 kg/cm2, which is the same as the pressure in the low pressure chamber 9, and the communication is established. Since the passage 33 and the pressure chamber 6 are simultaneously communicated with each other, the pressure in the variable pressure chamber 26 is also reduced to 5 kg/cm2, and the valve needle 22 is moved upward in the figure by the spring 23, and the injection ends. At that time, the load applied to the piezo stack 17 decreases, so the voltage decreases by about 160V. The ECU 102 detects the voltage drop and connects the communication passage 3.
3 is open, outputs the short signal shown in FIG. 4(f), and short-circuits the voltage of the piezo stack 17.

Thereafter, the application of voltage to the piezo stack 17 and the short-circuiting are repeated again until the communication passage 33 is closed. Eventually, the engine starts and the rotation speed reaches 150 rpm.
When it is above, the NE pulse signal can be detected,
Control is performed using normal control methods.

[0035]

As described above, according to the present invention, injection control at the time of starting can be performed without using the engine rotation signal (NE pulse signal) even in an electronically controlled fuel injection pump using a piezoelectric body. . For this reason, when the cranking speed is too low, such as when starting an engine at extremely low temperatures, NE
To reliably start an engine even when a pulse signal is not generated.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the structure of an embodiment of an electronically controlled fuel injection pump of the present invention.

FIG. 2 is a circuit diagram showing an embodiment of a drive circuit for carrying out the method for controlling an electronically controlled fuel injection pump according to the present invention.

[Figure 3] Control signals and currents in each part in the circuit of Figure 2,
FIG. 3 is a diagram showing the relationship with voltage.

FIG. 4 is a diagram illustrating the operation status of each part in FIGS. 1 and 2 when the control method according to the present invention is implemented.

[Explanation of symbols]

1...Fuel injection pump 2...Cylinder 3...Plunger 5...Groove 6...Pressure chamber 9...Low pressure chamber 17... Piezo laminate 22...Valve needle 26...Transformer room 31...Low pressure chamber passage 33...Communication passage 35...Pressure chamber passage 36...Check valve 102...ECU 200...Drive circuit 201...Trance 203, 207...transistor 204... Constant current control circuit

Claims (3)

[Claims] 1. A reciprocating plunger that pressurizes fuel in a pressure chamber formed in a cylinder, an injection fuel passage that supplies pressurized fuel in the pressure chamber to a fuel injection valve, and a predetermined pressure between the pressure chamber and the outside of the cylinder. an overflow passage that communicates with the low-pressure chamber, a valve body that opens and closes the overflow passage, a piezoelectric body that expands and contracts in accordance with the application of voltage, and that drives the valve body to open and close in accordance with the expansion and contraction of the piezoelectric body. a pressure transformation chamber that generates fluid pressure; and a switching means for closing an introduction passage communicating between the transformation pressure chamber and the low pressure chamber during a compression stroke of the plunger; In a fuel injection pump that controls fuel injection by controlling the voltage applied to the variable pressure chamber, means for allowing fuel to flow from the low pressure chamber to the variable pressure chamber when the pressure in the variable pressure chamber is lower than the pressure in the low pressure chamber. An electronically controlled fuel injection pump characterized by being provided with. 2. The electronically controlled fuel injection according to claim 1, wherein the voltage applied to the piezoelectric body is controlled by detecting the closing or opening of the introduction passage based on a change in the voltage applied to the piezoelectric body. How to control the pump. 3. When the closure of the introduction passage is detected by a voltage change of the piezoelectric body, the voltage applied to the piezoelectric body is maintained, and then the opening of the introduction passage is detected by a voltage change of the piezoelectric body. 3. The method of controlling an electronically controlled fuel injection pump according to claim 2, further comprising the step of canceling the voltage application to the piezoelectric body in the case where the piezoelectric body is not activated.