DE102005012004A1 - Counterbalanced forklift truck, has control device cooperating with rolling drive, working drive and steering lock drive such that device executes correction intervention maintaining or increasing stability against tilting of truck - Google Patents

Abstract

The truck has a sensor (S) to capture and transmit a physical variable to a control device (SE). The device uses specific data of truck stored on a calculation model (D). The device cooperates with a rolling drive, a working drive and a steering lock drive such that the device executes a correction intervention maintaining or increasing the stability against tilting of truck according to moving and loading state of truck. The physical variable comprises of lifting load, lifting height, lifting torque, inclination angle of mast, steering lock angle of steering axle, displacement direction, displacement speed, longitudinal acceleration and transversal acceleration and rate of yaw of the truck.

Description

The Invention relates to an industrial truck, in particular front-seat counterbalance forklift, with a height-adjustable and tilting load lifting device, a traction drive, working drives for the movements the lifting device and a steering drive.

at the most commonly used in practice trucks of the prior Technique requires the operator the weight of the load to be lifted (Lifting load) and the height, on which the load is lifted (lifting height), estimate. Based on that, the Driving speed and the curve radius of the truck be adjusted so that a tilting of the truck forward or sideways does not occur. This demanding task can overwhelm the operator and therefore when exceeded the carrying capacity of the truck or in driving maneuvers, which are not adapted to the current lifting capacity and lifting height, too Kippunfällen with serious injury or killing lead the operator or bystanders, associated with high property damage. It therefore does not have considerations lacking, appropriate safety precautions to avoid accidents with industrial trucks to accomplish.

So is in the DE 29 09 667 C3 described a generic truck in which intervened depending on the steering angle, the lifting height and the load torque in the drive and thereby the driving speed and possibly also the (electromotive) braking deceleration is limited. This is done by overriding the setpoint values specified by the operator with correction signals from the control device.

Subject of the EP 0 343 839 B1 is an industrial truck in which, depending on the lifting load, the lifting height, the steering angle, the direction of travel and the position of the vehicle's center of gravity, the driving speed is limited. In addition, it is also provided depending on the lifting height to limit the acceleration of the truck.

From the EP 1 078 878 A1 It is known to limit the tilting speed of a truck lift mast in dependence on the lifting load and the lifting height.

Finally, the reveals EP 1 019 315 B1 an industrial truck, in which the travel speed is limited hoisting load and tilt angle dependent and a higher lowering speed is possible without load.

all known proposals is common that always only partial aspects of the operating behavior of the truck considered and therefore operating conditions remain in which there is a significant risk of tipping.

Of the The present invention is therefore based on the object, an industrial truck to provide the type mentioned above, the possible all tilt-critical driving conditions a good tipping stability having.

These Task is inventively characterized solved, that based on vehicle-specific information calculation model for the static and / or quasi-static and the dynamic tilting behavior of the truck is stored in a control device to which a plurality of sensors for detecting for static and / or quasi-static and dynamic tilting behavior of the truck connected to relevant physical variables is, wherein the control means for determining an on the detected physical Sizes and the driving and loading state based on the stored calculation model is formed and with the traction drive, the work drives and the steering drive is in operative connection, depending on the ascertained driving and loading condition tipping stability or -increasing Corrective interventions are feasible.

Of the Thought essential to the invention is therefore, with the help of a Logic, which is executed by a control device and both the operating state "stati cal and / or quasistatic tilting "(at greater Lifting height and low driving speed or standstill) and the operating state "dynamic Tilting "(high lateral acceleration when cornering, high longitudinal acceleration when braking), to intervene so far in the vehicle behavior, that overturning is prevented.

Here, in an advantageous embodiment of the invention by the control device in a first engagement region in which exceeded a limit lifting height and a limit driving speed is exceeded, depending on the determined driving and loading the achievable or achieved operating speed, acceleration and deceleration acceleration and driving speed respectively reduced and in a second engagement region, in which the limit lifting height is exceeded and the limit driving speed is exceeded, depending on the determined driving and loading state increases the steering wheel torque and / or changed the steering ratio and / or achievable or scored Fahrge speed and working speed respectively reduced.

Of the first engagement area thus represents the range of static tilting or the area of the quasi-static tilting, in which the truck stands still or only has a relatively low driving speed, the lifting height However, it is relatively large. It is in this first intervention area depending on the driving and loading condition on the working speed of the load lifting device, the start-up and Braking acceleration and the driving speed of the truck acted in the sense of a limitation of the achievable actual values or in extreme cases in the sense of a reduction of the already achieved actual values.

This For example, by reducing the predetermined by the operator Setpoints are reached (override the setpoints specified by the operator by corrections from the control device). The at a certain deflection of control levers or other controls in normal operation corresponding ("achievable") actual values consequently reduced. In individual cases, this z. B. mean that with a stationary truck the operator by pressing a control lever, the lifted load at a certain speed wants to tilt forward, the tilting speed of the control device due to inadmissible greater Danger of tipping, however, is reduced to zero, so therefore the tilting movement is completely prevented to the front.

It but it is also possible to reduce already existing ("achieved") actual values by the control device. When approaching backward Truck the operator wants to lift the load. The controller leaves the Lifting to (possibly with reduced lifting speed), sets however, the starting acceleration and / or driving speed already achieved down.

Under Working speed of the lifting device is primarily understood the lifting and tilting speed. Also the lowering speed is preferably included. Of course, also other movements the load lifting device taken into account be, for. B. the movement of a side shifter or a pivoting device.

in the provided according to the invention second engagement area of the control device, namely the area Dynamic tilting, in which the truck with lowered load already exceeded a certain speed, the attacks Control device z. B. reducing the steering speed and changed if necessary, the steering ratio. Furthermore, alternatively or additionally the steering wheel torque required to turn the steering wheel is increased. About that also can - also alternatively or additionally - the achievable or achieved driving speed and working speed reduced become.

With the inventively designed truck especially tilting accidents avoided that from overly large, fast or abrupt positioning commands of the operator result (first Intervention area) as well as too fast cornering with and without Load (second engagement area).

In principle, four possible operating ranges of the truck are assumed:
In a first operating range with low lifting height, low center of gravity and low driving speed, no corrective intervention in the vehicle behavior takes place by the control device, because this area is to be regarded as uncritical.

One second operating range results at low driving speed and crossing a certain lifting height (Border-lift height). This operating range corresponds to the first one already described Engagement area in which the control device depends on Driving and loading conditions increase stability on the drive systems of the truck acts.

One third operating range is due to low lifting height (less than the limit lifting height) and increased driving speed (Exceed a limit driving speed). This is it around the already described second engagement area, in which the dynamic tilt stability by intervention of the control device z. B. in the steering ratio elevated becomes.

An operation of the truck in a fourth operating range with high driving speed and high lifting height can be prevented that inevitably before one of the two intervention areas must be run through and thereby the vehicle is placed in a tilt-proof state or a certain tipping stability is maintained. The two engagement areas are thus not left in the direction of the fourth operating area:
If the truck is initially in the first engagement area, then it is inevitably kept in a safe (tilt-stable) state by reducing the starting acceleration and the maximum achievable travel speed. On the other hand, if the vehicle is initially in the second engagement area (third operating area), the lifting becomes limited load and thus an operation of the truck in the fourth operating range also made impossible. Here too, the vehicle thus remains in a tilt-stable state.

Just the completeness it should be mentioned that it against the background of the valid legal regulations No technical intervention would be required at high speeds Lifting a (heavy) load beyond a certain lifting height prevent, because it would it is a so-called "not Proper use of the truck act, that is an obvious abuse by the operator, which is not the responsibility of the truck manufacturer.

It It is understood that the transitions between be fluent in the operating ranges described above can, so that the limit driving speed and / or the limit lifting height is not are fixed but can take on different values.

According to one advantageous development of the invention is in the first intervention area in each case preferably the achievable or achieved starting and braking acceleration and travel speed and in the second engagement area preferred the achievable or achieved operating speed of the lifting device reduced. So there is a prioritization, wherein in the first intervention area (static and / or quasistatic tilting), in which mainly the Working drive of the load lifting device is used, the traction drive influenced to increase the tipping stability and in the second engagement area (dynamic tilting) in which the use of the traction drive and the steering drive predominates, the anti-tipping measures concern the work drive.

In Embodiment of the invention are for the first engagement area direct or indirect sensors for detecting the lifting load, the lifting height, the Tilt angles, the load torque, the direction of travel, the driving speed and the steering angle and for the second engagement area in addition direct or indirect sensors for detecting the longitudinal acceleration, the lateral acceleration and the yaw rate provided. Out of the signal The steering angle sensor can also derive the steering speed become.

Some These sensors (eg tilt sensor, lift height sensor) are often in generic material handling equipment already available as standard or special equipment, so that the For the realization of the invention required effort relatively low is. This also applies to the signal paths between the controller and the drive systems of the truck. The tilt angle sensor can, depending on the design of the truck, the tilt angle of the mast or - with a fixed mast - the tilt angle of the height-adjustable on the mast Detect load carriage.

Conveniently, include the vehicle-specific stored in the control device Information at least data on the dimensions and masses of the Truck and the lifting device (lift mast), to the tire characteristics and for maximum payload.

In the controller is with the existing vehicle-specific Information and the physical detected by the sensors Sizes of Determined driving and loading condition, wherein at least the tilt critical maneuvers Brakes forward at vehicle inclination forward, accelerate backwards at Vehicle inclination to front, brakes from the reverse drive in a curve at vehicle inclination perpendicular to the tilting axis and accelerating in the forward drive in a curve at vehicle inclination monitored perpendicular to the tilt axis with regard to required interventions become.

With The term "vehicle inclination" is a relative slight inclination of the vehicle with respect to the plane. A Vehicle inclination is for example, then present when the vehicle is on a Hang is located (slope or slope z. B. less than 3%).

Further Advantages and details of the invention will be described with reference to the Schematically illustrated embodiments illustrated embodiment. there shows

1 a perspective view of an industrial truck,

2 a rule structure and

3 a state diagram.

The truck according to 1 is designed as a front-seat counterbalance forklift. A arranged on the vehicle front load lifting device 1 is powered by an extendable mast 1a and one on the mast 1a height-adjustable load carriage 1b with fork tines suspended in it 1c educated. With the help of forks 1c Cargoes of all kinds can be lifted and transported.

The mast 1a is tiltable about a horizontal axis arranged transversely in the lower region. Of course, it is also possible to provide a rigid, that is not tiltable mast and instead of carrying the load carriage not only vertically movable but also tiltable, as is often the case, for example, in so-called warehouse equipment (eg Reach truck). At the load carriage 1b can - depending on the application - also other load-bearing devices are attached. It is understood that in principle, additional movements of the load lifting device are possible, provided that the necessary facilities, such. As a side shifter, are available.

The mast 1a is by means of hydraulic tilting cylinders 1d tiltable. The extension of the mast 1a and lifting the load carriage 1b takes place by means of hydraulic lifting cylinders, possibly in addition with one or more load chains. For lowering the load carriage 1b or retraction of the lifting mast 1a act the weight of the load carriage and the upward extended components of the mast and possibly the weight of the load. The mentioned hydraulic consumers are powered by a hydraulic pump. Together with the required hydraulic valves and a motor driving the pump, this system thus comprises several working drives for the lifting, lowering and tilting movement of the lifting device.

The forklift according to embodiment further comprises a traction drive, in which a front axle 2 is designed as a drive axle, and a steering drive, with the aid of a rear-mounted steering axis 3 is pressed.

In 2 the control structure of the truck according to the invention is shown. From the originating from the operator specifications P to the accelerator pedals, the steering wheel and the operating levers results in a driving and loading condition Z, which is fed back to the operator in the form of a subjective perception W, whereupon the specifications P are possibly changed.

Of the Forklift is equipped with sensors S, with the help of which physical Sizes detectable are, from which determine the driving and loading Z objectively leaves. These sizes include the Lifting load L, the lifting height H, the load moment M, the mast tilt angle WM, the one taken on the steering axle Steering angle WL, the direction of travel R, the vehicle speed V, the Longitudinal acceleration BL, the lateral acceleration BQ and the yaw rate G. To determine the Load torque M can For example, the tilt cylinder forces or the axle load of the steering axle (Rear axle) are used. The lifting capacity L can be determined from the Hubzylinderkräften.

From the said sensors S is a part for the detection of physical Sizes provided for the Determination of static and quasi-static tipping hazards required are. These are the sensors for recording the direction of travel R, the vehicle speed V, the lifting load L, the Lifting height H, the load torque M, the mast tilt angle WM and the one taken at the steering axle Steering angle WL. For the determination of dynamic tipping hazards must include additional physical quantities become. For this purpose, sensors for detecting the longitudinal acceleration BL, the lateral acceleration BQ and the yaw rate G provided.

The Measured values acquired by the sensors S are sent to a control device SE, based on vehicle-specific data, such as z. B. the dimensions and masses of the truck and the mast, the tire characteristics and the maximum possible payload a calculation model D of the forklift is stored.

In the control device SE is in a driving condition observer FB from the calculation model D and the measured values of the sensors S the current driving and load Z of the truck determined and determined whether the working and / or driving movements are critical to tilting and therefore require intervention.

in this connection are from the driving state observer FB for a first intervention area E1 and for a second engagement area E2 critical driving maneuver FM1 or FM2 monitored. For the first engagement area E1, in which, if necessary, measures against static and / or quasi-static tilting, these are the maneuver brakes forward at Vehicle tilt forward, accelerate backwards at Vehicle tilt forward, brakes from the reverse drive in a curve at vehicle inclination perpendicular to the tilting axis and accelerating in the forward drive in a curve at vehicle inclination perpendicular to the tilt axis.

For the second Intervention area E2, in which action can be done against dynamic tilting, as a critical driving maneuver FM2 z. B. monitors the steering speed become. It can now the necessary interventions E in the traction drive, derived from the steering drive and working drive, which cause the tipping limits are not reached or exceeded. The control device SE thus acts to increase the stability of tilting.

The interventions performed are interventions in the intervention area E1 (eg reduction of driving and working speed) and to intervene in the engagement area E2 (eg reducing the vehicle speed, changing the steering ratio in order to reduce the steering speed), with each of which the operator's specifications P are corrected (connection K1), for example by overriding the setpoints. In addition, they may be interventions with which the specifications P are influenced at the moment of their formation (arrow K2), eg. B is an increase of the steering wheel torque required to rotate the steering wheel in the second engagement area E2.

This in 3 shown state diagram, in which the abscissa in the driving speed in km / h and the ordinate is the lifting height in mm, shows four operating areas I, II, III and IV. Here, a first operating range I starting from the coordinate origin by a limit lifting height GH (which is, for example, in a range between 330 and 600 mm) and a limit driving speed GF (which is, for example, in a range between 1 and 4 km / h) defined. While maintaining the limit driving speed GF is followed up to an operating range II, in which the lifting height is greater than the limit Hibhöhe GH. On the right side of the operating range I, ie when the limit driving speed GF is exceeded, there is a third operating range III below the limit lifting height GH. There remains a fourth operating range IV, in which both the limit driving speed GF and the limit lifting height GH are exceeded.

Of the Operating area I represents the area in which the danger from tipping accidents is lowest. It is therefore not necessary in operating area I that the control device engages tilt stability increasing.

in the Operating area II, ie the area with high lifting height but low driving speed, exists - dependent u. a. from the lifting load and the load moment - the danger of a static or quasi-static tilting. The operating area II therefore represents the first engagement region E1 of the control device, in which dependent from the determined driving and loading condition reducing to the achievable or achieved operating speed of the load lifting device, starting and braking acceleration and driving speed of the truck acted becomes. Overly large, fast or abrupt positioning commands of the operator are overridden and thereby the tipping stability elevated.

in this connection can the degree and extent of engagement will depend on whether only driving maneuvers in straight ahead direction exist, so no or only a small steering angle (or steering speed) is detected, or there is a quasi-static cornering, at the z. B. a steering angle of more than 5 degrees is detected or the steering speed exceeds a certain value.

A transition from division II to division IV is replaced by a stateful Limitation of the driving speed excluded.

in the Operating range III, in which the lifting height is relatively low and the driving speed is high, is additional a dynamic risk of tipping, namely z. B. when cornering (with and without load). The operating area III Therefore, the second engagement region E2 of the control device This is a tip over of the truck z. B. at fast Steering angle changes or in too fast cornering thereby prevents the control device -. B. dependent from the steering angle and the yaw rate - limits the steering speed and / or increases the steering wheel torque. Again, as an alternative or in addition, a limitation of achievable or achieved driving speed and working speed possible.

Around to avoid that the truck from the Operating area III out into the highly tipping operating area IV (size Lifting height, high speed), the lifting of the load can be limited or prevented.

Claims (6)

Industrial truck, in particular front-seat counterbalance forklift, with a height-adjustable and tiltable load lifting device, a traction drive, working drives for the movements of the load lifting device and a steering drive, characterized in that based on vehicle-specific information calculation model (D) for the static and / or quasi-static and the dynamic tilting behavior of the truck is stored in a control device (SE), to which a plurality of sensors (S) for detecting physical variables relevant to the static and / or quasi-static and dynamic tilting behavior of the industrial truck (V, R, H, M , L, WM, WL, BL, BQ, G), wherein the control means (SE) for determining one of the detected physical quantities (V, R, H, M, L, WM, WL, BL, BQ, G ) and the stored calculation model (D) based driving and loading state (Z) is formed and with the travel drive, the working drives and the steering drive is operatively connected in such a way that, depending on the determined driving and loading state (Z), tipping stability-preserving or -increasing corrective interventions (K1, K2) can be carried out. Truck according to claim 1, characterized in that by the control device (SE) in a first engagement region (E1), in which a limit lifting height (GH) exceeded and a limit driving speed (GF) is exceeded, depending on the determined driving and loading condition (Z) the achievable or achieved operating speed, acceleration and deceleration and Driving speed is respectively reduced and in a second engagement area (E2), in which the limit lifting height (GH) and exceeded the limit driving speed (GF) is exceeded, depending on the determined driving and loading condition (Z) increases the steering wheel torque and / or the steering ratio changed and / or the achievable or achieved driving speed and operating speed is reduced. Truck according to claim 2, characterized in that in the first engagement region (E1) prefers the achievable or achieved acceleration and deceleration and travel speed and in the second engagement area (E2) preferred the achievable or achieved operating speed of the lifting device is reduced. Truck according to claim 2 or 3, characterized in that for the first Engagement area (E1) Direct or indirect sensors (S) for recording the lifting load (L), the lifting height (H), the tilt angle (WM), the load torque (M), the direction of travel (R), the driving speed (V) and the steering angle (WL) and for the second engagement area (E2) in addition direct or indirect sensors (S) for detecting the longitudinal acceleration (BL), the lateral acceleration (BQ) and the yaw rate (G) provided are. Truck according to one of the claims 1 to 4, characterized in that in the control device (SE) contained vehicle-specific information at least data on the dimensions and masses of the truck and the lifting device, on tire characteristics and payload. Truck according to one of the claims 1 to 5, characterized in that in the control device (SE) at least the tilt-critical driving maneuvers (FM1) brakes forward at Vehicle tilt forward, accelerate backwards at Vehicle tilt forward, brakes from the reverse drive in a curve at vehicle inclination perpendicular to the tilting axis and accelerating in the forward drive in a curve at vehicle inclination monitored perpendicular to the tilt axis become.