Control device and method for influencing the engine speed and the degree of slip of a clutch of a ship drive system   

This application claims priority of German patent application no. 10 2008 025 480.0 filed May 27, 2008, which is incorporated by reference herein.

FIELD OF THE INVENTION

The present invention relates to a control device and a method for influencing the rotation speed of an engine, and the degree of slip of a clutch downstream therefrom, of a ship drive system, by way of an electronic control unit in accordance with a manual command transducer for selecting the rotation direction and travel speed.

BACKGROUND OF THE INVENTION

The area of application of the present invention extends to ship drive systems, preferably for the yacht-building sector. Ship drive systems driven by combustion engines and preferably having one or two marine propellers are usually utilized here. A rotary motion is imparted to the propellers via a transmission downstream from the engine. While the engine is usually controllable in terms of its rotation speed in order to define the ship\'s travel speed, the transmission is switchable in terms of rotation direction in order to make a selection between traveling ahead and back.

In many cases, a clutch that is adjustable in terms of its degree of slip is also integrated into the transmission, a trolling mode being controllable by varying the clutch slip. In this trolling mode, the engine speed usually remains constant in the vicinity of idle speed, while the ship\'s travel speed is determined by varying the degree of slip of the clutch. A trolling mode generated in this fashion can be used, for example, when traveling slowly in a harbor or during deep-sea fishing.

EP 0 524 992 B1 discloses a control device of the species. It encompasses control means and sensor means for influencing engine speed and the degree of slip of the clutch, which is connected on the input side to a command transducer for selecting the ship\'s direction of travel and speed by actuation of at least one control lever; with the control lever, it is possible to set a propeller shaft rotation speed and rotation direction, the maintenance of which is regulated by the control electronics in such a way that as a function of engine and transmission operating parameters to be maintained, an operating state is freely defined which is either a first operating state in which the propeller shaft rotation speed and rotation direction are implemented, with the clutch engaged, by modifying the engine speed, or a second operating state in which the propeller shaft rotation speed and rotation direction are implemented, at a predefined engine speed, by modifying the degree of slip of the clutch.

The sensor means necessary for the regulation of clutch operation result in considerable electronic complexity. In addition, the change in the degree of clutch slip that is implemented occurs abruptly, since the control output for the adjustable clutch is modified directly in accordance with the setpoint definition. This results in a high mechanical load on the drive train, especially when maneuvering.

SUMMARY

It is therefore the object of the present invention to create a control device for a ship drive system that ensures, in technically simple fashion, a clutch engagement operation having low impact on the drive system, in particular for a high-output engine system.

The object is achieved on the basis of a control device in accordance with the preamble of Claim 1, in conjunction with the characterizing features thereof. In terms of process engineering, the object is achieved analogously by Claim 5. In terms of an overall ship drive system arrangement, reference is made to Claim 10. The respectively referenced dependent claims reflect advantageous refinements of the invention.

The invention includes the technical teaching that upon engagement of the adjustable-slip clutch in order to enable travel ahead or back, a slip definition unit of the electronic control unit influences the degree of slip of the clutch in accordance with a ramp function characteristic curve, in order to decrease clutch slip during a defined clutch engagement time span.

The advantage of the solution according to the present invention is in particular that with it, smooth clutch engagement is achieved in simple fashion in terms of signal processing engineering, especially when changing the direction of travel. This is because control is not applied to the clutch by the discontinuity in control output, but instead the control output changes gradually in the direction of the desired clutch slip. The full output of the ship drive system is not thereby limited, but the clutch engagement operation is merely carried out with low impact on the drive system. In addition, thanks to the slower acceleration resulting from the ramp function characteristic curve the ship\'s master has more time to establish the desired maneuvering speed before the clutch must again be released. This makes maneuvering simpler and also safer. The adjustable-slip clutch transfers no torque at maximum slip, and the clutch engages at very low slip. This range characterizes the clutch slip “s”. The clutch engagement time span “t” for smooth clutch engagement is preferably in the range of a few seconds, very preferably in the range from 1 to 2 seconds. For larger ships having a greater inertia to be moved, and for ships with less excess power output, it is proposed to select a shorter clutch engagement time span “t”.

According to a feature that improves the invention, it is proposed that the electronic control unit split the control instruction predefined by the manual command transducer, i.e. delivers it simultaneously to a first converter unit for characteristic-curve-controlled determination of an engine speed signal for the downstream engine, and also to a second converter unit for characteristic-curve-controlled determination of a rotation direction signal for the downstream clutch. The slip definition unit that is a subject of the invention can be placed downstream from the second converter unit in order to perform its function for clutch control application. The slip definition unit is thereby optimally placed along the signal flow in order to perform its desired function of smooth clutch engagement.

According to another feature that improves the invention, it is proposed to insert a rotation speed limiting unit into the signal processing system between the first converter unit and the engine. At this point in the signal flow, the engine rotation speed is thus limited to a range suitable in particular for trolling operation, so as to ensure, in coaction with the slip definition unit according to the present invention, stable drive operation that can be easily controlled manually by the ship\'s master. The reason is that while the ramp function of the slip definition unit is active, the engine speed is held, by way of the limitation in rotation speed, in a range suitable for trolling operation.

In order to enable convenient maneuvering for the ship\'s master, it is preferable that both the direction of travel and the travel speed be manually definable, by way of the command transducer (embodied in conventional fashion) of the electronic control unit, depending on the selected position of at least one operating lever.

Further features that improve the invention are presented below, together with the description of a preferred exemplifying embodiment of the invention with reference to the single Figure. The Figure is a depiction, in the manner of a block diagram, of a ship drive system arrangement having an electronic control device.

DETAILED DESCRIPTION

According to the Figure, the control device encompasses a command transducer 1 for manually selecting the rotation direction and the travel speed of the ship (not further depicted here) as a function of the operating lever position selected by the ship\'s master. The control signal thereby generated goes to an electronic control unit 2 that performs a special signal processing action (described in further detail below) in order to establish at the output side the rotation speed “n” of an engine 3, as well as a degree of slip of an adjustable clutch integrated into a downstream transmission 5, and the rotation direction of transmission 5. Engine 3 is a combustion engine and is connected via a drive shaft 4 to the input of transmission 5. On the output side of transmission 5, a propeller shaft 6 extends to a propeller 7 for the purpose of driving the ship.

Electronic control 2 splits up, on the input side, the operating instruction predefined by manual command transducer 1 by the fact that said instruction goes both to a first converter unit 8 and to a second converter unit 9. First converter unit 8 determines, in accordance with the characteristic curve illustrated, an engine speed signal 13 for the connected engine 3. A rotation speed limiting unit 11 is interposed between first converter unit 8 and engine 3. Rotation speed limiting unit 11 limits the engine-speed, in particular to a range which is suitable for trolling operation and in which engine 3 has stable operating conditions.

Second converter unit 9, conversely, serves for characteristic-curve-controlled determination of a rotation direction signal 14 for transmission 4 connected thereto. Rotation direction signal 14 defines whether transmission 5 is to rotate forward or backward, in order cause the ship to travel ahead or back.

Upon engagement of the clutch of transmission 5 in order to initiate backward or forward travel, in the trolling mode a slip definition unit 10 is interposed in this case between second converter unit 9 and transmission 5. Slip definition unit 10 controls the degree of slip for the downstream clutch of transmission 5 in accordance with a ramp function characteristic curve. As a result of this ramp function characteristic curve, the clutch slip “s” is decreased for a clutch engagement time span s (in this case two seconds) in order to enable smooth clutch engagement at transmission 5. Slip definition unit 10 furthermore also generates a switching signal 17 to activate rotation speed limiting unit 11 to limit the rotation speed of engine 3, in order to ensure appropriately coordinated application of control to the ship drive system.

The invention is not limited to the preferred exemplifying embodiment described above. Modifications thereof are instead also conceivable, and are also encompassed by the scope of protection of the claims that follow. With the approach that is the subject matter of the present invention, for example, it is also possible to apply control to multiple transmissions having propeller shafts connected thereto, in order to ensure smooth clutch engagement of the connected ship drive system.

1 Command transducer

2 Control device

3 Engine

4 Drive shaft

5 Transmission

6 Propeller shaft

7 Propeller

8 First converter unit

9 Second converter unit

10 Slip definition unit

11 Rotation speed limiting unit

12 Signal splitting line

13 Engine speed signal

14 Rotation direction signal

15 Clutch slip signal

16 Trigger signal

17 Switching signal