DOUBLE PEDAL SYSTEM FOR AN INDUSTRIAL TRUCK

Abstract

A double pedal system for an industrial truck, comprising a first spring-reset pedal, a second spring-reset pedal. The first and the second spring-reset pedals are provided so as to be mechanically independent of one another, and are each provided with a device for electronically capturing the current actuation path of the corresponding pedal. A control unit which is operatively coupled to the devices for electronically capturing the actuation paths of the two pedals, and is designed to determine a travel target value from the current actuation paths of the two pedals. The invention furthermore relates to an industrial truck comprising a double pedal system of this kind, and to a method for operating the double pedal system.

Claims

1. A double pedal system for an industrial truck, comprising: a first spring-reset pedal, wherein the first spring-reset pedal is provided with a first device for electronically capturing a current actuation path of the first spring-reset pedal; a second spring-reset pedal wherein the second spring-reset pedal is provided with a second device for electronically capturing a current actuation path of the second spring-reset pedal; wherein the first spring-reset pedal and the second spring-reset pedal are provided so as to be mechanically independent of one another; and a control unit which is operatively coupled to the first device and the second device, and is designed to determine a travel target value from the current actuation path of the first spring-reset pedal and the current actuation path of the second spring-reset pedal.

2. The double pedal system according to claim 1, wherein the control unit is designed to determine the travel target value by calculating the difference between the two current actuation path of the first spring-reset pedal and the current actuation path of the second spring-reset pedal.

3. The double pedal system according to claim 1, wherein the control unit is further designed to determine a travel target direction, depending on the current actuation path of the first spring-reset pedal and the current actuation path of the second spring-reset pedal, during the determination of the travel target value.

4. The double pedal system according to claim 1, wherein the control unit is further designed to order a process for reducing the speed value of the industrial truck in the event of both the first spring-reset pedal and the second spring-reset pedal being deflected simultaneously.

5. An electrically operated industrial truck, comprising: a driver's seat; a double pedal system provided in a footwell in front of the driver's seat, the double pedal system comprising: a first spring-reset pedal and a second spring-reset pedal, wherein the first spring-reset pedal and the second spring-reset pedal are mechanically independent of one another; a first device for electronically capturing a current actuation path of the first spring-reset pedal; a second device for electronically capturing a current actuation path of the second spring-reset pedal; and a control unit operatively coupled to the first device and the second device, and configured to determine a travel target value from the current actuation path of the first spring-reset pedal and the current actuation path of the second spring-reset pedal, wherein the control unit of the double pedal system is operatively coupled to, or integrated with, a controller of a drive motor of the industrial truck.

6. The industrial truck according to claim 5, wherein the first spring-reset pedal is provided on a right-hand side with respect to a longitudinal central axis of the driver's seat, and the second spring-reset pedal is provided on a left-hand side with respect to the longitudinal central axis of the driver's seat.

7. The industrial truck according to claim 6, wherein the first spring-reset pedal and the second spring-reset pedal are each arranged obliquely with respect to the longitudinal central axis of the driver's seat, such that the first spring-reset pedal and the second spring-reset pedal each extends away from the longitudinal central axis, in a direction away from the driver's seat.

8. The industrial truck according to claim 5, further comprising a device for inductive braking of the industrial truck, wherein the control unit of the double pedal system and the device for inductive braking interact such that, in the event of both the first spring-reset pedal and the second spring-reset pedal being deflected simultaneously, the control unit actuates the device for inductive braking.

9. A method for operating a double pedal system of an industrial truck, the double pedal system comprising a first spring-reset pedal and a second spring-reset pedal, the method comprising the steps of: capturing a current actuation path of the first spring-reset pedal; capturing a current actuation path of the second spring-reset pedal; and determining a travel target value from the current actuation path of the first spring-reset pedal and the current actuation path of the second spring-reset pedal.

10. The method of claim 9, wherein the determination of the travel target value comprises determining a travel target direction.

11. The method of claim 9, wherein determining the travel target value comprises calculating a difference between the current actuation path of the first spring-reset pedal and the current actuation path of the second spring-reset pedal and scaling the calculated difference with respect to a maximally available drive power of the industrial truck.

12. The method of claim 9, wherein a first optical sensor is used for capturing the current actuation path of the first spring-reset pedal; and a second optical sensor is used for capturing the current actuation path of the second spring-reset pedal.

13. The method of claim 9, wherein a first rotary potentiometer is used for capturing the current actuation path of the first spring-reset pedal; and a second rotary potentiometer is used for capturing the current actuation path of the second spring-reset pedal.

14. The double pedal system of claim 5, wherein at least one of the first device or the second device comprises an optical sensor.

15. The double pedal system of claim 5, wherein at least one of the first device or the second device comprises a rotary potentiometer.

16. The double pedal system of claim 1, wherein at least one of the first device or the second device comprises an optical sensor.

17. The double pedal system of claim 1, wherein at least one of the first device or the second device comprises a rotary potentiometer.

Description

[0019] Further features and advantages of the present invention will become clear from the following description of an embodiment thereof, considered in conjunction with the accompanying drawings. In the drawings, in detail:

[0020] FIG. 1 is an isometric view of an industrial truck according to the invention;

[0021] FIGS. 2a and 2b are an isometric view and a view from below of the double pedal system of the industrial truck from FIG.

[0022] FIG. 3 is a flow diagram of the operating method of the

[0023] FIG. 4 shows temporal curves which illustrate the operation of the double pedal system of the industrial truck from FIG. 1.

[0024] FIG. 1 firstly shows an industrial truck according to the invention in an isometric view, which truck is denoted very generally by reference sign 10. Said industrial truck 10 is designed as a counterweight forklift and comprises conventional components such as a vehicle body 12, wheels 14, a counterweight 16 which receives, in the inside, components not shown in FIG. 1 such as a drive motor, a steering mechanism, hydraulic components, a control device, and optionally an accumulator, a lifting platform 18 comprising a load receiving means 20 in the form of a fork which can be displaced thereon in the vertical direction, and a driver's cab 22.

[0025] In turn, a driver's seat 24 is provided in the driver's cab 22, on which seat a driver of the industrial truck 10 sits during operation, and from where he can actuate various operating elements using his hands and feet. These operating elements comprise a steering wheel 26 and a pilot 28 which can be operated by the driver of the industrial truck 10, using his left or right hand, in order to steer the industrial truck 10 or to operate hydraulic components, such as the lifting function of the lifting platform 18.

[0026] Furthermore, a double pedal system 30 according to the invention is located in the footwell 22a in front of the driver's seat 24, which system will be described in greater detail in the following, with reference to FIGS. 2a and 2b. In this case, FIG. 2a shows the double pedal system 30 in a isometric plan view, a right-hand 34 and a left-hand 36 pedal being hinged to a base plate 32 in such a way that they extend, in each case, obliquely outwards with respect to the longitudinal central axis of the driver's seat 24, in the direction away from the driver's seat 24, in order to thereby be able to ensure an optimal anatomical position for the driver of the industrial truck 10.

[0027] It can be seen both from the isometric view in FIG. 2a and from the view from below in FIG. 2b that there is no mechanical coupling provided between the two pedals 34 and 36, and therefore said pedals 34 and 36 can be actuated in a manner completely independently of one another. In particular, the two pedals 34 and 36 are designed so as to be substantially structurally identical, and preloaded in the direction of an upper end position by means of respective spiral springs 38, which end position corresponds to a current actuation path of zero.

[0028] The driver of the industrial truck 10 can now exert a foot force counter to the action of these spiral springs 38, which force leads to a pivot movement of the corresponding pedal 34 or 36 about respective hinge pins 40. The deflection of the particular pedal 34 or 36 out of the zero position thereof, i.e. its current actuation path, is detected by means of a relevant suitable device 42 for electronically capturing the corresponding pedal 34 or 36, it being possible for the devices 42 to comprise for example an optical sensor or a rotary potentiometer.

[0029] The signals that are output by the two devices 42 and represent the particular current actuation path are output in a wired or wireless manner to a control unit (not shown) which determines a travel target value for the industrial truck 10 on the basis of said two current actuation paths, and then outputs this to a controller of a drive motor of the industrial truck 10, in order for this to be operated in a manner corresponding to the actuation of the pedals 34 and 36 by the driver of the industrial truck 10.

[0030] In this case, the flow diagram from FIG. 3 and the temporal curve from FIG. 4 show the functional principle of the operating method which is performed by the control unit discussed above. Firstly, with reference to FIG. 3, as discussed, in steps S1 and S2 the two devices 42 for electronically capturing the current actuation paths of the two pedals 34 and 36 output a captured value in each case, the two captured values being subtracted by the control unit in step S3.

[0031] In the present case, in the embodiment a simple subtraction of the two values, without further weighting or dynamic scaling, is intended to take place. In particular, the right-hand pedal 34 should accordingly correspond, in step S1, to a forwards movement, and the left-hand pedal 36 should accordingly correspond, in step S2, to a backwards movement. A case analysis is now carried out for the value S4 calculated in step S3, as to whether said value is greater or smaller than zero. In the event of a result “Yes”, said case analysis in step S5 leads to forwards travel, the calculated value of the travel target value from step S4 representing scaling for the maximally available drive power in step S6. In a similar manner, in the event of a determination of “No” in step S5, a backwards travel direction is determined in step S7, the value of the difference from step S3, i.e. the travel target value from S4, representing scaling for a maximum drive power in the rearwards direction.

[0032] Finally, with reference to FIG. 4 a travel procedure of the industrial truck 10, given by way of example, from FIG. 1, on the basis of two graphs of temporal curves, the top graph showing the respective current actuation magnitudes of the two pedals 34, 36, and the corresponding travel target value determined as the difference of said two values, while the bottom graph represents the speed curve of the industrial truck 10 over time.

[0033] In this case, five time periods T1 to T5 should be considered and described in the following. Furthermore, it is noted that, in the top of the two graphs, the curve having a percentage value of greater than or equal to 0 corresponds to a corresponding deflection of the right-hand pedal 34 corresponding to an instruction for travel in the forwards direction, while the curve having a percentage value of less than or equal to 0 corresponds to a deflection of the left-hand pedal 36 corresponding to an instruction for travel in the rearwards direction.

[0034] Thus, in the time period T1 firstly just the right-hand pedal 34 is deflected relatively quickly by its full maximum actuation path, while the left-hand pedal 36 remains unactuated, such that the travel target value increases to 100 percent in a similar manner, analogously to the deflection value of the right-hand pedal 34. Accordingly, a maximum output power is required from the motor of the industrial truck 10 in the forwards direction, leading to an acceleration up to the maximum speed of the vehicle 10 in approximately 5 seconds, and subsequent travel at maximum speed for the remainder of the time period T1. Subsequently, during the time period T2 the right-hand pedal 34 is furthermore kept at its maximum actuation, while in addition the left-hand pedal 36 is actuated successively, until it is fully deflected. Accordingly, the size of the difference of the two actuation paths returns to zero in the same amount as the actuation of the left-hand pedal 36 increases, such that the power required by the drive motor of the industrial truck 10 drops back to zero, and the industrial truck 10 accordingly slows until it comes to a stop. In this case, it is optionally possible for a braking device independent of the drive motor of the industrial truck 10, for example an induction brake, to be connected in addition, in the event of both pedals 34 and 36 being actuated simultaneously.

[0035] In the time period T3, the actuation of the right-hand pedal 34 is then successively withdrawn, while the actuation of the left-hand pedal 36 is further retained at 100 percent. Accordingly, the travel target value also reduces successively, to a negative maximum value at the end of the time period T3. Accordingly, the industrial truck 10 begins to travel backwards at an increasing acceleration, as is shown by the speed curve in the time period T3.

[0036] The travel target value has then reached a value of minus 100 percent at the start of the time period T4, and in addition the industrial truck 10 has reached its maximum speed in the backwards direction, which is, however, lower than the maximum speed in the forwards direction, as was achieved at the end of the time period T1.

[0037] Subsequently, in the time period T5, proceeding from the maximum actuation path of the left-hand pedal 36 present at the end of the time period T4, and the unactuated state of the right-hand pedal 34, sensitive changes of the two actuation paths of the pedals 34 and 36 are shown, which correspond, proceeding from the quick rearwards travel during the time period T4, to typical shunting operation of the industrial truck 10, the simultaneous actuation of the two pedals 34 and 36 making it possible for extremely precise setting of the desired current travel target value, and thus also the speed in the forwards or rearwards direction, to be achieved.