GB2172340A

GB2172340A - Turbocharger for diesel engine and method of controlling same

Info

Publication number: GB2172340A
Application number: GB08604132A
Authority: GB
Inventors: Yoshiyuki Ogata; Yoshiharu Okeda; Katsumi Akiyama; Isao Ueda; Fumitoshi Takahashi; Toshiyuki Tanaka; Shinji Nomura
Original assignee: Hitachi Zosen Corp
Current assignee: Hitachi Zosen Corp
Priority date: 1985-03-08
Filing date: 1986-02-19
Publication date: 1986-09-17
Also published as: GB8604132D0; JPS61205330A; CH668806A5; GB2172340B; DE3607612A1; FR2578581A1

Abstract

A turbocharger for a diesel engine comprising an exhaust turbine chamber 9 communicating with the exhaust pipe 7 of a diesel engine 1 and provided with a drive turbine rotor 14, a blower chamber 10 having a spiral chamber 19 communicating with the scavenging pipe 8 of the engine 1 and provided with a blower impeller 21 integrally rotatable with the turbine rotor 14, variable exhaust guide vanes 15 disposed in the turbine chamber 19 upstream from the turbine rotor 14, variable inlet air guide vanes 22 disposed in the chamber 10 upstream from the blower impeller 21, variable outlet diffuser vanes 25 disposed in the blower chamber 10 between the blower impeller 21 and the spiral chamber 19, and first, second and third drive devices 16, 23, 26 for controlling the exhaust guide vanes 15, air guide vanes 22 and diffuser vanes 25 according to the operating parameters of the turbocharger 2 and of the diesel engine 1. <IMAGE>

Description

SPECIFICATION Turbocharger for diesel engine and method of controlling same The present invention relates to a turbocharger for a diesel engine and a method of controlling same and, more specifically, to a diesel engine turbocharger including an exhaust turbine chamber communicating with the exhaust pipe of a diesel engine and provided with a drive turbine impeller, and a blower chamber having a spiral chamber communicating with the scavenging pipe of the engine and provided with a blower impeller integrally rotatable with the drive turbine impeller coaxially therewith, and to a method of controlling such a turbocharger.

A turbocharger of this type which is provided for supplying high-pressure air to a diesel engine functions to increase the output of the engine and to improve the combustion efficiency thereof. However, during partial load operation of the diesel engine, the actual operating point of the turbocharger deviates from a preset operating point, which leads to reduced efficiency of the turbocharger as well as to decreased combustion efficiency of the engine.

Attempts which have hitherto been made to avert such difficulty include, for example, the provision of a suction throttle in the air passage upstream from the blower room, the suction throttle being controlled through a control unit according to the pressure detected in the air passage downstream from the blower room and other operating parameters such as diesel engine speed and the like. With such an arrangement, however, no delicate control of the turbocharger can be achieved, since the flow rate and pressure of the supply air are regulated by the suction throttle alone. As such, no appreciable success has been achieved in improving the efficiency of the turbocharger or the combustion efficiency of the diesel engine.

The present invention has as its primary object the provision of a diesel engine turbocharger which eliminates aforesaid difficulty, and of a method of controlling same.

According to a first aspect of the invention, there is provided a turbocharger for a diesel engine comprising an exhaust turbine chamber communicating with the exhaust pipe of a diesel engine and provided with a drive turbine impeller, a blower chamber having a spiral chamber communicating with the scavenging pipe of the engine and provided a blower impeller integrally rotatable with the drive turbine impeller coaxially therewith, variable exhaust guide vanes disposed in the turbine chamber upstream from the turbine impeller, variable inlet air guide vanes disposed in the blower chamber upstream from the blower impeller, variable outlet diffuser vanes disposed in the blower chamber between the blower impeller and the spiral chamber, and first, second and third drive means for respectively controlling the discharge guide vanes, the air guide vanes and the diffuser vanes according to the operating parameters of the turbocharger and of the diesel engine.

Accordng to the above arrangement, it is possible to control the exhaust guide vanes, air guide vanes and diffuser vanes in accordance with the specific requirements determined by the operating parameters, so that the condition of the turbocharger can be regulated delicately andvariably so as to maintain the diesel engine in an ideal operating condition at all times.

According to a second aspect of the invention, a method of controlling the above defined turbocharger is provided which comprises supplying a preprogrammed control unit with operating parameters including the respective positions of the exhaust guide vanes, air guide vanes and diffuser vanes, the speed of the turbocharger, the outlet pressure and temperature of the blower chamber, the internal pressure of the spiral chamber at the outer periphery thereof, the pressure difference in the spiral chamber between the outer periphery and inner periphery thereof, the inlet temperature of the exhaust turbine chamber, the internal pressure of an air cooler connected to the scavenging pipe of the diesel engine, the speed of the diesel engine, and the rate of fuel flow into the diesel engine; and controlling the exhaust guide vanes, air guide vanes and diffuser vanes in accordance with instructions from the control unit.

Aforesaid control method is based on the fact that the three kinds of vanes permit delicate and various control of the turbocharger and is intended for utilization of various operating parameters compatible with the increased freedom of control.

Various features and advantages of the invention will be apparent from the following description of a preferred embodiment given in connection with the accompanying drawings, wherein: Figure 1 is a schematic diagram of a turbocharger embodying the invention as illustrated in association with a diesel engine; Figure 2 is a front view showing the exhaust guide vanes of the same turbocharger; Figure 3 is a front view showing the air guide vanes of the same turbocharger; Figure 4 is a front view showing the diffuser vanes of the same turbocharger; Figure 5 is a time chart illustrating an exemplary operating mode of the diesel engine; and Figure 6 is a flow chart illustrating an exemplary controling mode of the turbocharger.

In Figure 1, a diesel engine 1 and a turbocharger 2 connected thereto are controlled by a control unit 3 in an optimum manner.

The diesel engine 1 per se is of a known arrangement which is designed so that the reciprocating motion of pistons 6 (only one shown) within cylinders 5 is converted into the rotary motion of a crankshaft 4 located thereunder. Indicated at 7 is an exhaust pipe, at 8 a scavenging pipe, and at 8a an air cooler connected to the scavenging pipe 8.

The turbocharger 2, which constitutes the principal portion of the invention, includes an exhaust turbine chamber 9 and a blower chamber 10. The turbine chamber 9 has an inlet 11 which communicaters with the exhaust pipe 7 of the engine 1 through an exhaust conduit pipe 13, and an outlet 12. A drive turbine impeller 14 is rotatably disposed inside the turbine chamber 9 and has an output shaft 14a projecting into the blower chamber 10. Radially extending exhaust guide vanes 15, each rotatable about an axis perpendicular to the turbine shaft 14a, are disposed in a ring form, as shown in Figure 2, within the turbine chamber 9 upstream from the turbine impeller 14. The vanes 15 are rotated by first drive devices 16. The rotational angular position of the vanes 15 is detected by a first rotational angle detector A1.

The blower chamber 10 has an inlet 18 and a spiral chamber 19 having an outlet 19a which communicates with the scavenging pipe 8 of the engine 1 through an air conduit pipe 20. A blower impeller 21 fixed to the turbine shaft 1 4a is disposed within the blower chamber 10. Radially extending inlet air guide vanes 22, each rotatable about an axis perpen dicularto the turbine shaft 14a, are arranged in a ring form, as shown in Figure 3, within the blower chamber 10 upstream from the blower impeller 21.

The vanes 22 are rotated by second drive devices 23.

The rotational angular position of the vanes 22 is detected by a second rotational angle detector A2.

Further, outlet diffuser vanes 25, each rotatable about an axis parallel to the turbine shaft 14a, are disposed in a ring form (Figure 4) in the blower chamber 10 between the impeller 21 and the spiral chamber 19. The vanes 25 are adapted to-be driven by third drive devices 26. The rotational angular position of the diffuser vanes 25 is detected by a third rotational angle detector A3.

The control unit 3 receives detection signals from the first to third rotational angle detectors A1 to A3.

Further, the control unit 3 receives detection signals from a first rotation speed detector S1 for detecting the rotation speed of the turbine shaft 14a, a second rotation speed detector S2 for detecting the rotation speed of the engine crankshaft 4, a first pressure detector P1 for detecting the pressure at the blower outlet 1 9a, a first temperature detector T1 for detect ing the temperature at the blower outlet 1 9a, a second pressure detector P2 for detecting the inter nal pressure at the outer periphery of the blower spiral chamber 19, a pressure difference detector PD for detecting the pressure difference in the blower spiral chamber 19 between the outer periphery and inner periphery thereof, a second temperature detec tor T2 for detecting the exhaust gas temperature at the turbine chamber inlet 11, a third pressure detector P3 for detecting the pressure in the air cooler 8a of the engine 1, and a flow rate detector F for detecting the rate of fuel supply into the engine 1.

The control unit 3 is preprogrammed for optimum operation of the diesel engine 1 over the entire engine speed range.

The turbocharger of the above arrangement oper ates in the following manner. When the engine 1 is running, exhaust gas flows into the turbine chamber 9 through the exhaust gas conduit pipe 13 and the inlet 11 to rotate the turbine impeller 14, the gas being thereafter discharged through the outlet 12.

Consequently, the blower impeller 21 fixed to the turbine shaft 14a is rotated so that external air is sucked into the blower chamber 10 through the blower inlet 18, and compressed air is supplied to the engine 1 through the spiral chamber 19, blower outlet 1 9a and air conduit pipe 20 for combustion.

During this process, the signals from individual detectors A1, A2, A3, Si, S2Pr, P2 P3, PD, T1, T2, and F are supplied to the control unit 3, which in turn issues control signals C1, C2, C3 to actuate the first to third drive devices 16, 23, 26 respectively to rotate the exhaust guide vanes 15, air guide vanes 22 and diffuser vanes 25 as required by the preset program of the control unit 3, so that the rate and pressure of the air supply to the engine 1 are optimally controlled while preventing the turbocharger 2 from both overspeed and surging, the turbocharger 2 being controlled for maximum efficiency operation at the same time.

Figure 5 illustrates an exemplary operating mode of a marine diesel engine. After started, the engine is operated at harbour speed while the ship is in the harbour. When the ship enters a sea iane, the engine is operated at full or cruising speed. When the ship is passing through a canal, the engine is decelerated to dead speed. After the ship has entered the destination harbour, the engine is run at harbour speed again, and the engine is stopped at the pier.

Figure 6 is a flow chart illustrating a typical control mode provided by the control unit 3. When the engine 1 is started, the control unit 3 is switched on either automatically or manually into a standby state (block a). In this standby state (e.g., while the engine 1 is at harbour speed), the exhaust guide vanes 15, air guide vanes 22 and diffuser vanes 25 of the turbocharger 2 are locked at specific angular positions predetermined in relation to the maximum continuous output (hereinafter referred to as "MCO") of the engine 1 (block b). In the case of full automatic control, the second speed detector S2 detects the speed of the engine 1 (block c), and the detected value is compared with a manually variable reference value (e.g., 50%) of MCO) to judge whether the detected value is not less than the reference value (block d).If "YES", the engine speed is judged to have entered into a control range, and the control unit 3 starts controlling (block e). If "NO", the control unit 3 is maintained in the standby state until the engine speed reaches the reference value. Alternatively, the control unit 3 may be started manually (block fl before the engine speed reaches the reference value.

Upon start of control by the control unit 3, the rate of fuel supply to the engine 1 is first detected by the fuel flow detector F (block g), and on the basis of the detected fuel supply rate the angular positions of the vanes 15, 22, and 25 are adjusted through the drive devices 16, 23, and 26 (block h). Subsequently, the various operating parameters are comprehensively measured by the detectors A1, A2, A3, Sa, S2, P1, P2, P3, PD, T1, T2, and F (block i), and the air flow rate at the blower inlet 18 is calculated in the control unit 3 on the basis of the various detected values by using a known flow rate calculation method (blockj). The calculated value is examined as to whether or not it is within the allowable limits of a blower curve obtained through independent tests previously made with the turbocharger 2 (block k). If the calculated value is within the allowable limits, it is judged that there is no overspeed or surging of the turbocharger 2, and advance to the next control step is allowed. Conversely, if the blower air flow rate is not within the allowable limits, the angular positions of the vanes 15,22, 25 are readjusted through the drive devices 16, 23, 26 (block e), and the steps ito e are repeated until the blower air flow rate comes within the allowable limits of the blower curve.At the next step, the rate of air supply to the engine 1 is detected again by the fuel flow rate detector F (block m) to see whether it is less than the fuel supply value detected in the step g (block n). If "YES", the value detected in the step m is stored provisionally as minimum fuel flow rate. If "NO", the vanes 15, 22, 25 are readjusted to the fuel supply rate (block o), and the steps ito o are repeated until the result of the comparison becomes "YES". Subsequently, the engine speed is again detected by the second speed detector S2 (block) for comparison with the aforesaid reference value (block q). If the engine speed is not less than the reference value, the engine 1 is judged as still maintaining a normal running speed. In order to achieve a most economical fuel flow, the steps ito q are repeated, whereby the memory ofthe minimum fuel flow rate is successively renewed. When the engine speed is reduced below the reference value, the vanes 15, 22, 25 are locked at their respective preset angular positions as in the case of engine start. It is noted in this conjunction that even after the engine speed has been reduced as aforesaid, the control procedure may be manually forced back to the step g (blocks).

Generally, full automatic control would not be practiced while the ship is in a harbour or canal.

Claims

1. A turbocharger for a diesel engine comprising: an exhaust turbine chamber communicating with the exhaust pipe of a diesel engine and provided with a drive turbine impeller; a blower chamber having a spiral chamber communicating with the scavenging pipe of the diesel engine and provided with a blower impeller integrally rotatable with the drive turbine impeller coaxially therewith; variable exhaust guide vanes disposed in the turbine chamber upstream from the turbine impeller; variable inlet air guide vanes disposed in the blower chamber upstream from the blower impeller; variable outlet diffuser vanes disposed in the blower chamber between the blower impeller and the spiral chamber; and first, second and third drive means for controlling the discharge guide vanes, the air guide vanes and the diffuser vanes respectively according to the operating parameters of the turbocharger and of the diesel engine.

2. Aturbochargerassetforth in claim 1 wherein the discharge guide vanes are disposed in a ring form and each rotatable about an axis traversing the rotation axis of the drive turbine impeller.

3. A turbocharger as set forth i n claim 1 or 2 wherein the air guide vanes are disposed in a ring form and each rotatable about an axis traversing the rotation axis of the blower impeller.

4. A turbocharger as set forth in any one of claims 1 to 3 wherein the diffuser vanes are disposed in a ring form and each rotatable about an axis parallel to the rotation axis of the blower impeller.

5. A method of controlling the turbocharger set forth in any one of claims 1 to 4, which comprises supplying a preprogrammed control unit with operating parameters including the respective positions of the exhaust guide vanes, air guide vanes, and diffuser vanes, the speed of the turbocharger, the outlet pressure and temperature of the blower chamber, the internal pressure of the spiral chamber at the outer periphery thereof, the pressure difference in the spiral chamber between the outer periphery and inner periphery thereof, the inlet temperature of the exhaust turbine chamber, the internal pressure of an air cooler connected to the scavenging pipe of the diesel engine, the speed of the diesel engine, and the rate of fuel flow into the diesel engine; and controlling the exhaust guide vanes, air guide vanes and diffuser vanes in accordance with instructions from the control unit.

6. Aturbochargerfor a diesel engine substantially as described herein with reference to and as illustrated in the accompanying drawings.

7. A method of controlling a turbocharger as claimed in claim 1, substantially as described herein.