Trim indicator for boats with outboard propeller drive units
The present invention relates to an indicator instrument for boats with an outboard drive unit which can be adjusted to various angles in relation to the transom of the boat and has a sensor designed to send to the instrument an electrical signal dependent on said adjustment angle, said instrument being provided with indicator means for indicating said angle within the entire adjustment range of the drive unit. 
     Previously known instruments of this type indicate the angular setting of the drive unit by analog means with a pointer on a scale which covers the entire adjustment range of the drive unit. The scale can be colored to facilitate reading. For example, the scale can be green within the trim range and red outside this range. The problem is however that the trim range varies for different outboard drive units and different boats, which can also be more or less sensitive to trimming. The trim range markings are thus only of help in those cases where the markings happen to agree with the actual trim range of the boat. In all other cases, the operator must keep in mind the boat&#39;s actual trim range and disregard the trim range markings on the instrument when the drive unit is trimmed. The trim range markings are in these cases only misleading and it is quite possible that the operator will still tend to trim the drive unit within the range marked on the instrument. 
     The purpose of the present invention is to produce an indicator instrument of the type described by way of introduction, in which the disadvantage of the above-mentioned known instruments is eliminated. 
     This is achieved according to the invention by virtue of the fact that the instrument has a second indicator means for indicating angular intervals within a limited angular range within the adjustment range, means being provided for manual selection of one of a plurality of limited angular ranges. 
     In a particularly advantageous embodiment of the instrument according to the invention, the instrument comprises a microprocessor in which said plurality of limited angular ranges are programmed, a switch for selection of angular range, a window for digital indication of the adjustment angle within the entire adjustment range of the drive unit, and a stack of light emitting diodes for indicating the angular interval within the selected limited angular range. 
     The invention is based in principle on the idea of separating range indication and angle indication from each other in order to make it possible when installing the instrument to select and set a trim range for the instrument which agrees with the actual range for the drive unit and boat in each individual case. As previously, the first indicator displays--preferably digitally for more accurate reading--the angular setting of the drive unit. This indicator does not however provide any information concerning within which of the ranges trim, beach, or tilt, this angle lies. This information is obtained instead from the second indicator. The invention thus provides an instrument which clearly and unambigously provides all the required information in a manner which is quite easy to grasp and easily read if the digital angle indication is combined with LED-indication of the trim range. 
    
    
     The invention will be described in more detail below with reference to an example shown in the accompanying drawings, of which 
     FIG. 1 shows a front view of an instrument according to the invention, and 
     FIG. 2 shows a block diagram of the instrument. 
    
    
     The instrument has a housing 1, for flush mounting in an instrument panel for example. The housing contains the required electrical components for the indications given below and is provided on its back with connections for electric current and for an angle sensor on the drive unit. 
     On the front of the instrument there is an indicator window 2 in which the angle of the drive unit in relation to a reference plane transverse to the boat is indicated digitally with liquid crystals. Beneath the window 2 there is an LED stack 3 consisting of five LEDs 4 arranged beside a symbol 5 which depicts the cruising attitude of the boat at various trim angles. The stack 3 and the symbol 5 thus provide a rough indication of the trim angle. To one side of the trim indicator there is another indicator consisting of a drive unit symbol 6 and an LED 7 placed at the tip joint. 
     These two last-mentioned indicators provide information telling in which of the three ranges the angle shown on the digital indicator lies. The three ranges are: 
     (1) The trim range, i.e. the angular range for the outboard unit for operation at speeds above the low-speed range; 
     (2) The beach range, i.e. the angular range for the outboard unit for operation at low speeds when passing obstacles such as sand bars, rocks etc.; 
     (3) The tilt range, i.e. the angular range for the outboard unit within which the propeller housing is completely or almost completely lifted out of the water. 
     As long as the drive unit angle is within the trim range, one or more of the LEDs 4 will be lighted depending on the trim angle. When the drive unit is trimmed outside the trim range and into the beach range, LED 7 is lit and gives a steady light as long as the angle lies within the beach range. When it is tilted into the tilt range, LED 7 will flash. 
     According to the invention, the instrument is designed so that it can be set for various trim ranges. The table below relates to an embodiment in which one of four trim ranges can be selected with the aid of a switch. The table shows the angular interval for each LED 4 in the stack 3 and the angle at which LED 7 starts to give off a steady light. 
     
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DIP switch position                                                       
4           3          2         1                                        
Trim limit                                                                
LED No.                                                                   
       6°                                                          
                8°  12°                                     
                                   16°                             
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4:1    -4°, -3°                                             
                -4°, -3°                                    
                           -4°˜-2°                    
                                   -4°˜-1°            
4:2    -2°, -1°                                             
                -2°˜0°                                
                           -1°˜1°                     
                                   0°˜3°              
4:3    0°, 1°                                               
                1°, 2°                                      
                           2°˜4°                      
                                   4°˜7°              
4:4    2°, 3°                                               
                 3°˜5°                                
                           5°˜7°                      
                                    8°˜11°            
4:5    4°, 5°                                               
                6°, 7°                                      
                            8°˜11°                    
                                   12°˜15°            
7      above 6°                                                    
                above 8°                                           
                           above 12°                               
                                   above 16°                       
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     As shown in the block diagram in FIG. 2, the instrument includes a microprocessor in which the above trim angle ranges are programmed. The desired range is selected by a DIP switch on the back of the instrument. The total indication range is in the example -6° to +63°. The limit of the tilt range, at which LED 7 changes from a steady to a flashing light, is at 45°. 
     In addition to electric current connections, connections for a trim angle sensor and a connection for a lamp switch, the instrument has a connector for a relay 10 designed to control electro-hydraulic equipment for adjusting the trim angle. Within the trim range, the relay is turned on and off by means of a manual switch 11. At the trim limit given in the above table, the instrument cuts off the current to the relay however. If the drive unit is then to be trimmed out further, then a switch 12 must be actuated simultaneously with the switch 11. There is thus no risk that the drive unit will be unintentionally trimmed into the beach range or the tilt range.