DE102016220441A1 - Apparatus and method for controlling an internal combustion engine of a watercraft - Google Patents

Abstract

The invention relates to a device and a method for controlling an internal combustion engine of a watercraft, wherein the internal combustion engine is connected to a propeller via a propeller shaft, the device comprising a control unit that controls the internal combustion engine, wherein the device comprises a first knock sensor connected to the control unit is connected, wherein the first knock sensor is arranged such that it can detect a cavitation on the propeller.

Description

State of the art

Move objects such. For example, under high speed impellers of pumps or propellers underwater, areas of very low pressure may be created within the water due to the high velocity. Since the boiling point of water is pressure-dependent, it may happen that at a given water temperature, the boiling point of water is locally lower. The water goes into the gaseous phase. As the pressure increases again, the gas bubble just formed collapses and water forms again in liquid form. This formation and collapse of the gas bubbles is called cavitation. When operating the propulsion of a watercraft that has a propeller, this cavitation effect should be avoided, as it on the one hand causes an increased noise level and on the other hand makes the power transmission of the propeller to the water inefficient.

From the DE 198 48 726 A1 is a safety device to prevent cavitation in pumps known. It is provided to attach a sound sensor to the pump housing and read this sound sensor with a special evaluation circuit. This evaluation circuit is designed to analyze the noise that causes the pump and thus to be able to detect cavitation.

Knock sensors are known from the automotive industry, which can detect the knocking of an internal combustion engine via the detection of structure-borne noise. If the knocking of a cylinder of an internal combustion engine is detected by a control unit, appropriate countermeasures are taken by the control unit in order to reduce knocking.

In the field of watercraft, there remains a need to provide a cost effective and flexible solution for operating a propeller without cavitation effects.

Disclosure of the invention

The device according to the invention for controlling an internal combustion engine of a watercraft has the advantage that a first knock sensor, which is connected to a control unit, is arranged such that it can detect a cavitation on the propeller which is connected to the internal combustion engine by means of a propeller shaft.

According to the invention, it has been recognized that knock sensors from the automotive sector can be used not only for detecting the knocking of a cylinder of an internal combustion engine, but also for detecting a cavitation of a propeller. Thus, there is a particularly cost-effective way to detect the cavitation on a propeller.

Particularly advantageous is a device in which the knock sensor is arranged on the propeller shaft or a bearing of the propeller shaft. The structure-borne noise within the propeller caused by the cavitation effect is transmitted to the propeller shaft and the bearings on which the propeller shaft is mounted, so that it can be detected in a particularly simple manner by a knock sensor arranged there.

It is also advantageous to arrange the knock sensor on a side wall of the watercraft, which has a passage for the propeller shaft, so that a cavitation noise caused by the propeller can be detected by the knock sensor. As a rule, this side wall is the rear side wall of the vessel. The sound caused by the cavitation effect is transmitted through the water to the side wall of the vessel located in the vicinity of the propeller, so that a knock sensor arranged there can detect the cavitation in a reliable manner.

A further advantage of this arrangement is that the sensor can be mounted with particularly simple means, since it does not have to be connected to a moving part nor must it be arranged in the immediate vicinity of parts of the drive train of the watercraft. Thus, for example, a watercraft can be retrofitted with the device according to the invention without having to undertake extensive reconstruction measures.

Advantageously, a device comprising a second knock sensor, wherein the second knock sensor is arranged on the internal combustion engine. With this advantageous embodiment of the device according to the invention, not only the cavitation effect on the propeller can be detected, but also a conventional knocking in the cylinders of the internal combustion engine can be detected and, if necessary, remedied.

Particularly advantageous is a device in which the same hardware, in particular with regard to a layout and a placement of a board, for the cavitation recognition as well as for the knock detection is used. It was recognized that engine control units are being developed for engines with different numbers of cylinders, and that the maximum number of knock sensor inputs required for this purpose has been maintained in the layout and in part also in the assembly becomes. By the optional use of the same hardware for detecting knock as well as for detecting cavitation, the variety of variants can be reduced under the engine control units and the cavitation control can be realized particularly cost-effective.

Also advantageous is a method for controlling an internal combustion engine of a watercraft, wherein the internal combustion engine is controlled by a control unit, wherein the control unit is connected to a first knock sensor, wherein a signal of the first knock sensor is evaluated by the first control unit to detect cavitations on the propeller ,

Particularly advantageous is a method in which an output variable of the internal combustion engine is reduced if cavitation is detected on the propeller when the signal of the first knock sensor is evaluated.

It is particularly advantageous if the output quantity is a rotational speed or a torque.

Particularly advantageous is a method in which the signal of the first knock sensor is evaluated with a knock detection unit of a control unit. In particular, the knock detection unit may be a software-implemented area of the control unit, which is conventionally used to detect a knocking of a cylinder of the internal combustion engine. This has the advantage that conventional engine control software can be used to detect the cavitation effect on the propeller of the craft. An adaptation of the software is thus advantageously not necessary.

The present invention also includes a computer program that is set up or compiled to perform each step of the method of the invention. According to the invention, an electronic storage medium is also provided, on which the computer program is stored. Furthermore, a control unit is provided according to the invention, which comprises the electronic storage medium.

Hereinafter, an embodiment of the present invention will be explained in more detail with reference to the accompanying drawings. Showing:

list of figures

• 1 a schematic representation of a watercraft with the device according to the invention and;
• 2 : a schematic representation of the method according to the invention.

1 shows a schematic representation of a watercraft ( 10 ), via an internal combustion engine ( 20 ), which has a propeller shaft ( 22 ) a propeller ( 24 ) can drive. The propeller shaft ( 22 ) by means of at least one warehouse ( 26 ) stored. A rear side wall ( 15 ) of the vessel ( 10 ) has a passage through which the propeller shaft ( 22 ) from inside the watercraft ( 10 ) into the water, where the propeller ( 24 ) is located.

The watercraft ( 10 ) further comprises a control unit ( 30 ), which in turn is an electronic storage medium ( 35 ). In addition, the control unit ( 30 ) at least one knock detection unit ( 37 . 38 ) configured to detect a knocking of a cylinder of an internal combustion engine. In the knock detection unit ( 37 . 38 ) may in particular be a software module within the control unit ( 30 ) act. A hardware implementation of the knock detection unit ( 37 . 38 ) is also possible.

A first knock sensor ( 40 ) is directly on the ship's side ( 15 ), which pass through the passage for the propeller shaft ( 22 ). The first knock sensor ( 40 ) is above a signal line to the control unit ( 30 ) and there in particular with the knock detection unit ( 37 . 38 ) in connection. A second knock sensor ( 42 ) is in direct contact with the internal combustion engine ( 20 ). The second knock sensor ( 42 ) is also connected to the control unit via a signal line ( 30 ), in particular with a knock detection unit ( 37 . 38 ) in connection. The first knock sensor ( 40 ) and the second knock sensor ( 42 ) stand in each case with a knock detection unit ( 37 . 38 ) in connection.

The control unit ( 30 ) is via a signal line to the internal combustion engine ( 20 ), so that the control unit ( 30 ) the internal combustion engine ( 20 ) in such a way that the internal combustion engine ( 20 ) provides a desired torque or speed.

In an alternative embodiment of the invention, the first knock sensor (40 *) is not located directly on the side wall ( 15 ), which has a passage for the propeller shaft ( 22 ) but is located on the propeller shaft ( 22 ) or at a bearing of the propeller shaft ( 26 ). This alternative form of the device according to the invention is in 1 shown that there is the first knock sensor not only with the reference numeral 40 , but also with the alternative reference numeral 40 * finds.

It should be noted that, according to the invention, it is in particular not intended to fasten both a knock sensor to the side wall and to fasten another knock sensor to the propeller shaft or to a bearing of the propeller shaft.

2 shows a schematic representation of the method according to the invention. In a first step ( 100 ), the inventive method is started. Then follow step 110 ,

In step 110 is the signal of the first knock sensor ( 40 , 40 *) from the control unit ( 30 ) in particular by the knock detection unit ( 37 . 38 ) to detect a cavitation effect on the propeller ( 24 ) to recognize. Form at the propeller ( 24 ) Cavitation bubbles, this produces a characteristic sound coming from the first knock sensor ( 40 , 40 *) can be detected, since the sound is either as structure-borne sound via the propeller shaft ( 22 ) or through the water to the ship's side ( 15 ), which has a passage for the propeller shaft ( 22 ) is worn. Shows when reading the signal of the first knock sensor ( 40 , 40 *) no signal pattern, characteristically for the occurrence of cavitation bubbles on the propeller ( 24 ) is typical, the process in step 110 continued. Shows itself in the signal of the first knock sensor ( 40 , 40 *) a pattern typical of cavitation bubbles on the propeller ( 24 ) is, so goes with step 120 continued.

In step 120 controls the control unit ( 30 ) the internal combustion engine ( 20 ) such that the requested torque and / or the requested speed is reduced compared to the requested torque and / or the requested speed of an immediately preceding time. Then, branch back to step 110 , Alternatively, the monitoring with regard to the occurrence of cavitation bubbles according to step 110 be done permanently, even if necessary step at the same time 120 is executed, in which the power of the internal combustion engine is reduced. In an alternative embodiment of the method according to the invention is in step 110 additionally the signal of a second knock sensor ( 42 ) evaluated to knock the internal combustion engine ( 20 ) to recognize. Gets in step 110 a knocking of the internal combustion engine is detected, also becomes step 120 branches, in which the torque request or the speed request to the internal combustion engine ( 20 ) is reduced. Subsequently, step 110 carried out.

The inventive method ends by switching off the internal combustion engine ( 20 ) or in that it is switched off explicitly by means of a non-activated actuator.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19848726 A1 [0002]

Claims (11)

Device for controlling an internal combustion engine of a watercraft, wherein the internal combustion engine is connected to a propeller via a propeller shaft, comprising a control unit that controls the internal combustion engine, comprising a first knock sensor, which is connected to the control unit, characterized in that the first knock sensor arranged such is that he can detect cavitation on the propeller. Device after Claim 1 , characterized in that the first knock sensor is arranged on the propeller shaft or on a bearing of the propeller shaft. Device after Claim 1 , characterized in that the first knock sensor is mounted on a side wall of the watercraft, which has a passage for the propeller shaft, in such a way that a cavitation noise caused by the propeller can be detected. Device according to one of Claims 1 to 3 comprising a second knock sensor disposed on the internal combustion engine. Method for controlling an internal combustion engine of a watercraft, which drives a propeller by means of a propeller shaft, wherein the internal combustion engine is controlled by a control unit, wherein the control device is connected to a first knock sensor, characterized in that a signal of the first knock sensor is evaluated by the control unit to cavitation to recognize the propeller. Method according to Claim 5 , characterized in that an output variable of the internal combustion engine is reduced when cavitation is detected on the propeller during evaluation of the signal of the first knock sensor. Method according to Claim 6 , characterized in that the output quantity is a rotational speed or a torque. Method according to one of the preceding claims, characterized in that the signal of the first knock sensor is evaluated with a knock detection unit of the control device. Computer program that is set up or compiled to compile each step of the method according to one of Claims 5 to 8th perform. Electronic storage medium on which the computer program is based Claim 9 is stored. Control unit, which the electronic storage medium after Claim 10 includes.

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