JP2003299371A5

JP2003299371A5 -

Info

Publication number: JP2003299371A5
Application number: JP2002098581A
Authority: JP
Filing date: 2002-04-01
Publication date: 2005-05-19
Anticipated expiration: 2022-04-01

Description

インジェクタを構成する可動部材の摺動抵抗等が温度変化の影響を受けて、インジェクタの作動特性が変化する。一方、前記のごとく、検出電流が予め設
定した所定の電流値をとるまでの時間はインジェクタの温度とみなせるピエゾスタックの温度に応じて変化し、冷却水温度等に比してはるかにインジェクタ温度と対応した温度情報である。したがって、計測された前記時間に応じてピエゾスタックの充電時期および充電保持期間の長さを補正することで、燃料噴射を高精度に行い得る。
請求項１０記載の発明では、ピエゾアクチュエータに搭載されたピエゾスタックの駆動用のエネルギーを蓄積するコンデンサと、該コンデンサとピエゾスタックとの間で一方を供給元として、インダクタを介して電荷を移動する通電経路とを有し、該通電経路として、スイッチング素子のオンオフを繰り返すことにより、スイッチング素子のオン期間にインダクタに漸増する電流が流れる第１の種類の通電経路と、前記スイッチング素子のオフ期間に前記インダクタに漸減する電流が流れる第２の種類の通電経路とが形成され、かつ、前記スイッチング素子を制御する制御手段により、ピエゾスタックの充電および放電がなされるピエゾアクチュエータ駆動回路において、
前記スイッチング素子よりも前記ピエゾスタック側で、前記通電経路の電圧を検出する電圧検出手段を設け、
前記電圧検出手段により検出された電圧が予め設定したしきい値を越えると、電圧異常と判断する。
これにより、充電電圧が過昇したことを判断できる。
The sliding resistance or the like of the movable member constituting the injector is affected by the temperature change to change the operating characteristic of the injector. On the other hand, as described above, the time until the detection current takes a predetermined current value changes in accordance with the temperature of the piezo stack that can be regarded as the temperature of the injector, and the injector temperature is much longer than the coolant temperature etc. And corresponding temperature information. Therefore, the fuel injection can be performed with high accuracy by correcting the charge timing of the piezo stack and the length of the charge holding period according to the measured time .
In the invention according to claim 10, a capacitor for storing energy for driving a piezo stack mounted on a piezo actuator, and charges are transferred between the capacitor and the piezo stack via the inductor with one serving as a supply source. The first type of conduction path through which current gradually increases in the inductor during the on period of the switching element by repeating on and off of the switching element as the conduction path, and the off period of the switching element In a piezoelectric actuator drive circuit, in which a second type of conduction path through which a gradually decreasing current flows in the inductor is formed, and a control unit that controls the switching element charges and discharges the piezo stack.
A voltage detection unit that detects a voltage of the conduction path on the piezo stack side with respect to the switching element;
When the voltage detected by the voltage detection means exceeds a preset threshold value, it is determined that the voltage is abnormal.
Thereby, it can be determined that the charging voltage has risen excessively.

Claims

A capacitor for storing energy for driving a piezo stack mounted on a piezo actuator, and a conduction path for transferring charge via an inductor, using one of the capacitor and the piezo stack as a supply source, As the conduction path, by repeating on and off of the switching element, a first type of conduction path through which current gradually increases in the inductor during the on period of the switching element and current gradually decrease in the inductor during the off period of the switching element In a piezo actuator drive circuit in which a second type of current path is formed, and a control unit that controls the switching element charges and discharges the piezo stack.
A current detection means for detecting a current flowing through the conduction path;
The control means is set to judge that a failure has occurred when the current detected by the current detection means exceeds a preset threshold value, and to set the mode of the failure as a short circuit failure. Piezo actuator drive circuit.

The piezoelectric actuator drive circuit according to claim 1, wherein, as the piezo stack, a plurality of piezo stacks can be connected with a common conduction path and can be connected among the plurality of piezo stacks by a selection switch controlled by the control means. From which it is possible to select the piezo stack to be connected to the current path,
A piezoelectric actuator drive circuit, wherein the control means is set to open the conduction path by turning off the selection switch when it is determined that the short circuit failure has occurred.

3. The piezoelectric actuator drive circuit according to claim 1, further comprising: voltage detection means for detecting a voltage of the conduction path on the side closer to the piezo stack than the switching element.
When it is determined that the control means is the short circuit failure and the detected voltage is a first determination condition that is less than or equal to a preset threshold value, the supply path is used as the piezo stack with the charge source as the piezo stack. A piezoelectric actuator drive circuit configured to allow charge collection to be collected in the capacitor and to prohibit the charge collection when the detected voltage is a second determination condition that is equal to or greater than a preset threshold value.

4. The piezoelectric actuator drive circuit according to claim 3, wherein the threshold of the detection voltage is set substantially to a voltage between both terminals of the capacitor,
A piezoelectric actuator drive circuit, wherein the control means is set to determine the failure mode as the ON failure of the switching element when the second determination condition is satisfied when the switching element is OFF.

5. The piezoelectric actuator drive circuit according to claim 3, forming a path for an emergency discharge for discharging the charges of the capacitor through the inductor and bypassing the piezo stack to the ground side, and A piezoelectric actuator drive circuit provided with an emergency discharge switch for opening and closing the emergency discharge path in the path of

The piezoelectric actuator drive circuit according to any one of claims 1 to 5, wherein the capacitor is charged by a power supply unit controlled by the control unit,
A piezoelectric actuator drive circuit configured to stop the operation of the power supply unit when it is determined that the control unit is the short circuit failure.

A capacitor for storing energy for driving a piezo stack mounted on a piezo actuator, and a conduction path for transferring charge via an inductor, using one of the capacitor and the piezo stack as a supply source, As the conduction path, by repeating on and off of the switching element, a first type of conduction path through which current gradually increases in the inductor during the on period of the switching element and current gradually decrease in the inductor during the off period of the switching element In a piezo actuator drive circuit, which switches between charging and discharging of the piezo stack by a control unit which forms a second type of current path and controls the switching element.
Voltage detection means for detecting the voltage of the non-ground side terminal of the piezo stack;
The control means is set to determine that the piezo stack has a failure when a voltage detected in a charge holding period after charging of the piezo stack is smaller than a preset threshold value. Piezo actuator drive circuit.

A capacitor for storing energy for driving a piezo stack mounted on a piezo actuator, and a conduction path for transferring charge via an inductor, using one of the capacitor and the piezo stack as a supply source, As the conduction path, by repeating on and off of the switching element, a first type of conduction path through which current gradually increases in the inductor during the on period of the switching element and current gradually decrease in the inductor during the off period of the switching element In a piezo actuator drive circuit, in which a second type of conduction path is formed and charging and discharging of the piezo stack are performed by control means for controlling the switching element,
A current detection means for detecting a current flowing through the conduction path;
Immediately after the start of charging of the piezo stack, the control unit measures a time until the detected current takes a predetermined current value, and when the measurement time deviates from the predetermined range, the piezo stack A piezoelectric actuator drive circuit characterized in that it is set so as to determine an apparent capacitance abnormality of the piezoelectric stack or a temperature abnormality of the piezo stack.

An injector that operates a needle that opens and closes a fuel injection hole by a piezo actuator;
As a means for driving the piezo actuator,
A capacitor for storing energy for driving a piezo stack mounted on a piezo actuator, and a conduction path for transferring charge via an inductor, using one of the capacitor and the piezo stack as a supply source, As the conduction path, by repeating on and off of the switching element, a first type of conduction path through which current gradually increases in the inductor during the on period of the switching element and current gradually decrease in the inductor during the off period of the switching element A piezo actuator drive circuit in which a second type of current path is formed, and the control unit controlling the switching element charges and discharges the piezo stack;
A fuel injection device comprising command means for commanding the charge timing and charge holding period length of the piezo stack corresponding to the fuel injection timing and injection amount in the control means, wherein the piezoelectric actuator drive circuit ,
A current detection means for detecting a current flowing through the conduction path;
Immediately after charging of the piezo stack starts, the command unit measures the time until the detected current takes a predetermined current value, and based on the measurement time, charging timing and charging of the piezo stack A fuel injection device set so as to correct the length of a holding period.

A capacitor for storing energy for driving a piezo stack mounted on a piezo actuator, and a conduction path for transferring charge via an inductor, using one of the capacitor and the piezo stack as a supply source, As the conduction path, by repeating on and off of the switching element, a first type of conduction path through which current gradually increases in the inductor during the on period of the switching element and current gradually decrease in the inductor during the off period of the switching element In a piezo actuator drive circuit in which a second type of current path is formed, and a control unit that controls the switching element charges and discharges the piezo stack.
A voltage detection unit that detects a voltage of the conduction path on the piezo stack side with respect to the switching element
The piezoelectric actuator drive circuit, wherein it is determined that the voltage is abnormal if the voltage detected by the voltage detection means exceeds a preset threshold value.