Abstract:
A manually controlled operating lever for a vehicle operator&#39;s platform has an electrical actuation transducer for transmitting control signals to a working function as a function of the pivoting of the lever and/or as a function of the actuation of at least one actuation element arranged on the lever. In order to avoid an undesired release of working functions, a manually operated activating element is mounted near a hand grip of the lever, and is coupled to a switching element which operates to activate the actuation transducer for the transmission of control signals as a function of actuation of the activating element.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a manually controlled operating lever, in particular for the operator&#39;s platform of a vehicle, with at least one electric actuation transducer for the generation of control signals to at least one working function as a function of the pivoting of the lever and/or as a function of the actuation of an actuating element arranged on the lever. 
     For the actuation of the working functions, a multitude of manually controlled operating levers are found on the operator&#39;s platform of utility vehicles. These levers can be used, for example, to operate implements, such as front loaders. To an increasing degree these levers operate not only through mechanical linkages, but they contain switches or other electrical actuation transducers which transmit electrical control signals as a function of actuation of the lever, in order to control the working functions as desired by the operator. Manually controlled operating levers are known that are equipped with push button switches in the region of the operating handgrip, which interact with an actuation transducer configured as a switching element. A modem manually controlled operating lever moves relatively easily and can be actuated with very little force. This increases the danger of an undesired actuation and control of the working functions. An unintentional actuation and control of a working function can occur, for example, if a piece of the operators clothing catches on the manually controlled operating lever and pivots the latter without the operator noticing the movement. An unintentional actuation of the lever can actuate working functions unexpectedly, resulting in dangerous situations. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a manually controlled operating lever which prevents unintentional actuation of working function. 
     Another object of the present invention is to provide such a lever wherein the actuation of working functions is blocked under certain circumstances. 
     This and other objects are achieved by the present invention, wherein a manually actuated activating element is provided in the region of the operating handgrip of the manually controlled operating lever and is connected to an electrical switching element. The switching element interacts with an electrical locking control unit or a locking logic circuit in order to activate or deactivate the actuation transducer of the lever for the transmission of control signals as a function of actuation of the activating element. The locking control unit is designed so that control signals from the control element are transmitted to the working function only if the activating element has previously been deliberately actuated. Otherwise the control signals are suppressed. 
     Thus, the transmission of operating signals to working functions requires an actuation of the manually controlled operating lever or an actuating element as well as the activating element. With an appropriate grasping of the activating element it is very unlikely that the two noted actuations are performed at the same time unintentionally and involuntarily. The danger of an accidental operation is thereby practically eliminated. Preferably, the lever is configured in the form of a joy stick, which can be pivoted in two directions about a universal joint and is forced into its central neutral position by a spring. For each direction of pivoting at least one actuation transducer is provided for the control of at least one associated working function. Manually controlled operating levers configured as joy sticks permit a simple operation of several working functions. Such a joystick type lever is particularly advantageous for the operation of a loader, in particular the loader of an agricultural or industrial utility vehicle. By a forward or backward movement of the joy stick the loader arm of the loader can be lowered or raised and by sideways movement of the joy stick, for example, a shovel or another implement of the loader can be pivoted. An unintentional and unexpected actuation of the loader arm and the implement must be prevented, since personnel can be present in the region of the loader. 
     Preferably, push button switches may be used, for example, for the operation of a loader and may be employed to actuate a lifting device for the loading implement or to close or to open the jaws of a grasping implement. It may be advantageous to provide at least one rocker switch element in the region of the operating handgrip which is connected with at least one actuation transducer configured as a potentiometer for the generation of a control signal corresponding to the rocker position of the rocker switch element. Usually one potentiometer is sufficient, that can control both directions of the rocker switch and whose output signal for the rest position of the rocker switch element is calibrated to a null signal. However a potentiometer may be provided for each direction of the rocker switch element movement. By actuating the rocker switch the oil flow, for example, of a hydraulically operated working function can be controlled in proportion to the position of the rocker switch element. Here the working function may be a hydraulic implement attached to the vehicle (grasping device, lifting device, rotating mechanism). 
     Preferably, the activating element is connected in a joint to the lever so as to move about a pivot axis. The actuation transducer is activated for the transmission of control signals to the working function only if the activating element is deflected by hand from its rest position against a small force (for example, spring force, gravity force). The deflection and the retention in the deflected position requires only a small force, so that the operator is not impaired by the actuation of the activating element. Preferably, the activating element is configured as a flap and is connected in a joint to the manually controlled operating lever in the shank end region of the operating handgrip over a pivot axis extending transverse to the longitudinal axis of the lever. Also, the lever is designed so that the activating element has a generally L-shaped cross section, where the end of the first leg is connected in a joint to the lever and the end of the second leg is located near the free end of the operating handgrip when the activating element is not actuated and does not project beyond it. At the same time the second leg extends in the vicinity and parallel to the operating handgrip. In order to grasp the operating handgrip, the hand must be inserted between the operating handgrip and the activating element. Due to the close distance between the second leg and the operating handgrip, this is only possible if the second leg pivots away from the operating handgrip, at which point the associated switching element is triggered. 
     Preferably, the activating element is provided with an actuation device in the vicinity of its connecting joint, such as a projection, which interacts with an actuation pin of the switching element, so that, when the activating element is pivoted outward from its non-operating rest position, the switching element is actuated in order to transmit control signals to a locking control unit. 
     An electrical control unit evaluates the signals of the actuation transducer and the switching element. The control unit contains a locking control unit and transmits control signals to the associated working functions as a result of the aforementioned signals as a function of an appropriate locking strategy. 
     Preferably, the electrical control unit receives and evaluates the signals of the actuation transducer, which responds to the pivoting of the lever, as well as the signals of the switching element that is connected to the locking element. The control unit performs an activation of the actuation transducer, that is, a further transmission of signals of the actuating transducer to the associated working function, only if the activating element is triggered (actuated), while the lever is in its neutral position. However, if the lever is initially in a different position than its neutral position, then the actuation transducer is not activated upon an actuation of the activating element. Hence the activation is possible only from the neutral position of the lever. This has the safety related advantage that a movement of the working function (for example, front loader) can only be performed if the lever is moved, but not, for example, if the vehicle ignition is turned on when the lever is in its deflected position. 
     If the activated lever is pivoted from its neutral position, the activation remains in effect even if the activation element is returned to its rest position. However, a preferred embodiment of the invention provides that the control unit cancels the activation if the activation element is in its rest position (because it was released from the hand) and the lever returns to its neutral position and remains there longer than a predetermined first time interval. The first time interval may, for example, amount up to two seconds, preferably approximately 0.5 seconds. Hence, if the lever returns to its neutral position, then the activation ceases after a short time. To generate control signals it is then necessary to perform a renewed activation, as described above. Upon a brief passage through the neutral position, however, the activation is not canceled if the activation element is not actuated. 
     In order to exclude any misuse and any circumvention of the locking philosophy, in which the operator fixes the activating element by other assisting means (adhesive tape) in its actuated position, so as to hold the lever permanently in its activated position, a preferred embodiment of the invention provides for the control unit to cancel the activation when, after actuating the activation element the lever returns to this neutral position and remains there longer than a predetermined second time interval. The second time interval amounts preferably to up to three minutes, preferably approximately one minute. However, if the neutral position is passed through only briefly, the activation remains in effect. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view of a manually controlled operating lever according to the invention. 
     FIG. 2 shows an electrical schematic block diagram for the lever of FIG. 1, showing a control circuit for three working functions. 
     FIG. 3 shows is a logic flow diagram illustrating a method of operation of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 shows a manually controlled operating lever  10 . The lever  10  is a spring-centered lever configured in the form of a joy stick that can be pivoted in two directions by means of a universal joint  12 , not described in any further detail, to the front and the rear or to the left and right. The lever  10  consists generally of an operating hand grip  14 , a central housing  16  and a lever shank  18  located just below the housing  16  whose lower end engages the universal joint  12 . The shank  18  of the lever is coupled to actuation transducers  19 ,  21 , such as potentiometers, which generate electrical proportional signals (x, y of FIG. 2) representing the position of the lever  10  along two axis. 
     Two operating members or push button switches  20 ,  22  are located on the upward facing end surface of the operating hand grip  14 . Switches  20 ,  22  are associated electrical actuation transducers (not shown in any further detail). With the switches  20 ,  22  the operator can transmit control signals (z 1 , z 2 ) in order to switch, for example, between different supplemental functions. 
     A manually operated rocker member  24  includes an upper rocker leg  26  and a lower rocker leg  28 , and is arranged on the side of the hand grip  14  facing away from the operator. 
     The rocker member  24  is associated with an actuation transducer  25 , such as a potentiometer, which transmits control signals to attached implements which are proportional to the rocker position. 
     In the region of the shank side of the operating hand grip  14  an activating element  34  (safety flap), configured as a flap, is connected in a joint to the housing  16  through a pivot axis  32  extending transverse to the lever axis  30 . Element  34  is forced into its rest position shown in FIG. 1 by a spring (not shown), with a low spring force. The activating element or lever  34  has a generally L-shaped cross section with two legs  36 ,  38 . The free end of the first leg  36  together with the pivot axis  32  forms the connecting joint of the activating element  34 . The second leg  38  extends at an acute angle towards the longitudinal lever axis  30  and ends in the vicinity of the upper free end of the operating hand grip  14 . The free, rounded end of the second leg  38  does not extend beyond the end face of the operating hand grip  14  and therefore does not offer any point of attack for an accidental deflection. 
     A projection  40  extending downward is formed onto the first leg  36  of the activating element  34 . This interacts with the actuating pin  42  of a switching element  44  (such as a micro switch) which is biased by a spring towards the projection  40 . In the rest position as shown the projection  40  does not engage the actuating pin  42 , so that the latter does not transmit any control signals of the switching element  44 . 
     In order to grasp the operating hand grip  14 , the operator inserts his fingers between the activating element  34  and the operating hand grip  14  and forces the activating element  34  from its rest position as shown to the left (as seen in FIG.  1 ). Thereby the free end of the second leg  38  moves away from the operating hand grip  14 . Simultaneously, the projection  40  makes contact with the actuating pin  42  and releases a switching function in the switching element  44 . If the operator removes his hand from the operating hand grip  14 , then the activating element  34  pivots back into its base position under the force of the spring. Thereby the switching element  44  is switched back and does not transmit any control signal. 
     Furthermore, as seen in FIG. 2, a toggle switch  45  is arranged on the housing  16 . Switch  45  can be toggled between an ON and an OFF position in order to switch the lever  10  into the condition in which it is ready to operate. 
     The signals representing the operating members  20 ,  22 , the transducers  19 ,  21  and  25 , and the switch  44  are evaluated by a control unit  46 , which transmits control signals to actuators  48 ,  50 ,  52  corresponding to an evaluation algorithm. The actuators  48 ,  50 ,  52  control associated hydraulic valves  54 ,  56 ,  58  of working functions. The valves  54 ,  56 ,  58  are, for example, electro-hydraulic control valves of a front loader. For example, the valve  54  controls the lifting and lowering of a loader arm, not shown, the valve  56  controls the tilting of a grasping device at the free end of the loader arm and the valve  58  controls the opening and closing of the grasping device. The control of a hydraulic attached implement by means of the rocker element  24  is not shown in FIG. 2 in any further detail. The push button switches  20  and  22  may be used to switch between different supplementary functions. 
     The control unit  46  executes an algorithm which evaluates the signals received by it. A suitable algorithm is illustrated and explained in connection with the logic flow diagram of FIG.  3 . The algorithm begins with the switching of the toggle switch  45  with step  100 . In step  102  the lever  10  is not yet activated, that is, the control unit  46  does not convert the signals representing the operating members  20 ,  22 , the transducers  19 ,  21  and  25  and the switch  44  into control signals for the working functions. Step  104  determines whether the lever  10  is in its neutral position and whether the activating element  34  is in its rest position. As long as these two conditions are not fulfilled, the algorithm repeats step  104  at regular time intervals. If the two conditions of step  104  are fulfilled, the algorithm proceeds to step  106 , which determines whether the activating element  34  has been actuated in the interval and has left its rest position. As long as this is not the case, step  106  is repeated at regular time intervals. If an actuation of the activating element  34  is detected by step  106 , then the algorithm proceeds to step  108 , by means of which the lever  10  is activated. 
     The lever  10  is now in its operating condition in which control signals are transmitted to associated working functions as a function of its pivoting. Step  110  determines whether the lever  10  is in its neutral position. If this is not the case, the activation of the lever  10  is maintained and step  110  is repeated, and the lever  10  remains in its operating condition, even if the activating element is released and returns to its rest position. 
     If, however, it is determined in step  110  that the lever  10  is in its neutral position, then the algorithm proceeds to step  112  in which determines whether the activating element  34  is still being actuated. 
     If the answer to step  112  is positive, then the algorithm proceeds to step  114 , which determines whether the activating element  34  has been actuated continuously for the last full minute. If this is the case, then in step  116  the lever  10  is deactivated and the algorithm is returned to step  104 . This has the result that when the lever  10  is in its neutral position, it remains activated only if the activating element  34  has been actuated no longer than one minute. Otherwise the activation is canceled. This prevents the activating element  34  from being blocked by unauthorized means, without the operator grasping the lever  10  and simultaneously actuating the activating element  34  with his hand. 
     If the answer in step  114  is negative, that is, the activating element was not actuated continuously for the last minute, while the operating lever  10  was in its neutral position, then the algorithm returns to step  110  and the lever  10  remains activated. 
     If it is determined in step  112  that the activating element  34  is no longer actuated, then the algorithm proceeds to step  118 , which determines whether the activating element  34  was not actuated during the last half second. If this is the case, then in step  116  the lever  10  is deactivated and the algorithm is returned to step  104 . Otherwise, the algorithm returns to step  110 . Thus, when the activating element  34  is not actuated, the lever  10  can be moved through its neutral position only briefly without being automatically deactivated. If, however, it remains in its neutral position for a longer period of time (longer than 0.5 seconds), when the activating element  34  is not actuated, then it is deactivated. In this case the interrogation loop must be run again starting with step  104 . 
     While the present invention has been described in conjunction with a specific embodiment, it is understood that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, this invention is intended to embrace all such alternatives, modifications and variations which fall within the spirit and scope of the appended claims.