A Load Handling Apparatus For A Forklift

Abstract

A load handling apparatus for a load handling vehicle such as a forklift including a rear load handling section including mounting means for securing the rear load handling section to the lifting mechanism of a forklift mast assembly. A front load handling section in use supports the load. The front load handling section is rotatably mounted to the rear load handling section, such that the front load handling section is able to rotate relative to the rear load handling section. The load handling apparatus has a lateral axis transverse to the rotational axis of the front load handling section. Actuating means are arranged to rotate the front load handling section relative to the rear load handling section, and an attitude sensor is configured to provide a signal indicative of the lateral attitude of the rear load handling section (38) relative to the horizontal.

Claims

1. A load handling apparatus for a load handling vehicle comprising: a rear load handling section including mounting means for securing the rear load handling section to the lifting mechanism of a forklift mast assembly; a front load handling section which in use supports the load, rotatably mounted to the rear load handling section, such that the front load handling section is able to rotate relative to the rear load handling section, the load handling apparatus having a lateral axis transverse to the rotational axis of the front load handling section; actuating means arranged to rotate the front load handling section relative to the rear load handling section; an attitude sensor configured to provide a signal indicative of the lateral attitude of the rear load handling section relative to the horizontal; and a controller configured to automatically control the actuating means in response to a signal from the attitude sensor to rotate the front load handling section relative to the rear load handling section to optimize load stability.

2. The load handling apparatus according to claim 1, wherein the controller determines the optimum rotational position of the front load handling section required to optimise load stability.

3. The load handling apparatus according to claim 1, wherein the controller is configured to automatically actuate the front load handling section to a substantially laterally horizontal attitude in response to a signal from the attitude sensors.

4. The load handling apparatus according to claim 3 further comprising at least one inertial sensor for sensing lateral inertial forces; wherein the controller is configured to determine the optimum rotational position of the front load handling section based on both the lateral horizontal attitude of the rear lead handling plate and the detected inertial force.

5. The load handling apparatus according to preceding claim 1, wherein the front load handling section comprises a support plate and at least two lifting tines mounted to and extending perpendicularly away from the front face of the support plate in a spaced arrangement.

6. The load handling apparatus according to claim 5, wherein the rear load handling section comprises a support plate arranged substantially parallel to the front support plate and wherein the mounting means are secured to the rear face of the rear support plate.

7. The load handling apparatus according to claim 1, wherein the front load handling section is rotatably mounted to the rear load handling section by a rotational mounting and the actuating means is a linear actuator having a first end rotatably mounted to the rear load handling section and a second end rotatable mounted to the front load handling section at a location radially spaced from the rotational mounting such that linear actuation of the actuator causes rotational movement of the front load handling section relative to the rear load handling section about the rotational mounting.

8. The load handling apparatus according to claim 7, wherein a projection extends from the rear face of the front load handling section at a location radially spaced from the rotational mounting to which the second end of the linear actuator is rotatably mounted.

9. The load handling apparatus according to claim 8, wherein the linear actuator is mounted to the rear face of the rear load handling section and the rear load handling section comprises an arcuate slot through which the projection of the front section extends, the slot having a radius corresponding to the radial distance of the projection from the rotational axis of the rotational mounting.

10. The load handling apparatus according to claim 9, wherein the load handling apparatus has a longitudinal axis extending parallel to the rotational axis of the rotational mounting which in use aligns with the longitudinal axis of the load handling vehicle with the longitudinal horizontal attitude of the front load handling section being define by the position in which the longitudinal axes of the lifting tines are horizontally arranged, wherein the attitude sensor is configured to provide a signal to the controller indicative of the longitudinal horizontal attitude of the vehicle, and the controller is configured to generate a control signal in response to said signal to in use control the mast assembly actuator of a forklift truck to alter the in a longitudinal attitude of front load handling section relative to the horizontal to optimise load stability.

11. The load handling apparatus according to claim 10, wherein the controller determines the optimum longitudinal attitude of the front load handling section relative to the horizontal to optimise load stability.

12. The load handling apparatus according to claim 1, wherein the attitude sensor comprises at least one gyroscope and at least one accelerometer.

13. A load handling vehicle comprising the load handling apparatus according to claim 1.

14. The load handling vehicle according to claim 13 further comprising: a vehicle body; a mast assembly pivotally mounted to the vehicle body and slidingly mounted to the rear load handling section; a mast assembly actuator arranged to pivot the mast assembly relative to the body; and a lifting actuator connected to the rear load handling section and a connected to raise and lower the rear load handling section along the length of the mast assembly; wherein the front load handling section comprises a support plate and at least two lifting tines mounted to and extending perpendicularly away from the front face of the support plate in a spaced arrangement, and the load handling apparatus has a longitudinal axis extending parallel to the rotational axis of the rotational mounting with the longitudinal horizontal attitude of the front load handling section being define by the position in which the longitudinal axes of the lifting tines are horizontally arranged; and wherein the controller is configured to automatically control the mast actuator in response to a signal from the attitude sensor indicative of the longitudinal horizontal attitude to move to the lifting tines to a horizontal attitude.

15. The load handling vehicle according to claim 14, wherein the controller is configured to determine the velocity of the vehicle and to override the vehicle controls and decelerate the vehicle when it is determined that the velocity exceeds maximum load stability parameters.

Description

[0037] The present invention will now be described by way of example only with reference to the following illustrative figures in which:

[0038] FIG. 1 shows a forklift truck including a load handling apparatus according to an embodiment of the invention;

[0039] FIG. 2 is a side view of the arrangement of FIG. 1;

[0040] FIG. 3 is a front view of the arrangement of FIG. 1; and

[0041] FIG. 4 is a view of the arrangement of FIG. 1 from below and to the rear.

[0042] Referring to FIG. 1, a forklift truck 1 comprises a truck 2 having a body 4 including a frame 6 and a wheel base 8. The truck 2 has a rear end 10 and a front end 12 with a longitudinal axis being defined between the front 10 and back 12 along the length of the vehicle in line with its direction of travel. Vertical supports or masts 14 are mounted to the frame or chassis 6 of the truck 2 at the front end 12. The mast assembly 14 is pivotally mounted to the frame 6 by pivotal mountings 16 which are located towards the base of the mast assembly. Hydraulic cylinders 18 are pivotally connected at a first end 20 to the frame 6 and at their distal ends 22 to the mast assembly 14.

[0043] As shown in FIG. 2 the mast assembly 14 includes a pair of vertically arranged elongate members which are laterally spaced by a distance less than the width of the truck 2. A pair of cylinders 18 is provided at either side at the front 12 of the truck 2 corresponding to the lateral locations of the mast assembly 14. Each cylinder 18 is secured to the corresponding mast 14 at a location vertically spaced above the pivot connection 16 connecting the corresponding mast 14 to the frame 6. The mast assembly 14 is connected at the upper ends by a bridging member 24 which reinforces and maintains the spacing of the mast assembly 14. Each mast 14 includes a guide channel 26 extending along its length at its front edge.

[0044] A load handling apparatus 28 is located in front of the mast assembly 14. The load handling apparatus 28 includes a pair of substantially L-shaped tines 30 each having a lift support section 32 extending forwardly in a substantially horizontal attitude. The load handling apparatus 28 is connected on its rear side to a hydraulic cylinder 34 secured to the truck 2. The cylinder 34 is substantially vertically oriented and secured to the rear side of the load handling apparatus 28 to raise and lower the load handling apparatus 28 in the vertical direction. As shown in FIG. 2 the rear side of the load handling apparatus 28 includes two pairs of rollers 36 arranged in a transversely spaced relationship with the rollers being aligned with and received within the corresponding channels 26 of the mast assembly 14. The channel 26 acts as a guide channel with the rollers 36 rolling within the guide channels 26 as the load handling apparatus 28 is raised and lowered by the cylinder 34.

[0045] The load handling apparatus 28 comprises a rear carriage plate 38 defining a rear section of the load handling apparatus, and a front carriage plate 40 defining a front section of the load handling apparatus 28. Fork tines 30 are secured to the front face of the front carriage plate 40 by upright sections 33 that form the rear section of the L-shaped tines, and are arranged such that the lifting section 32 of each tines extend substantially perpendicularly relative to the front carriage plate 40 away from the front carriage plate 40 proximate its lower. The front face of the front carriage plate 40 and the upright sections 33 of the tines 30 provide a vertical backstop for the load. The forks 30 are laterally spaced across the front carriage plate 40 and are located substantially at its outer edges with each fork 30 being spaced an equal distance inwardly from the outer edge of the front carriage plate 40.

[0046] The front carriage plate 40 comprises a substantially rectangular panel 42 and may also include lateral reinforcing members 44 located at the upper and lower front edges. As shown in FIG. 3 the front carriage plate 40 is secured to the rear carriage plate 38 by a rotational mounting 44. The rotational mounting is preferably a bearing assembly such as a needle bearing assembly, although a bush arrangement is also contemplated. The rotational mount 46 is located centrally in the width-wise direction proximate the upper edge of the front carriage plate 40 and rear carriage plate 38. The front carriage plate 40 is rotatable about its upper edge on the rotational mount 46 relative to the rear carriage plate 38.

[0047] The rear carriage plate 38 is secured to the cylinder 34 and the rollers 36 are secured to the rear face of the rear carriage plate 38 such that the rear carriage plate 38 is slidingly received in and vertically guided by the guide slots 26 of the mast assembly 14. The rear carriage plate 38 is therefore rotationally fixed relative to the mast assembly 14, and transversely fixed relative to both uprights of the mast assembly 14 and the truck 2.

[0048] As shown in FIG. 4 a pin 48 extends from the rear face of the front carriage plate 40. The pin 48 extends through a slot 50 formed in the rear carriage plate 38. The pin 48 is transversely aligned with the rotational mount 46 and is located a spaced distance vertically beneath the rotational mount 46 proximate the lower edge of the front carriage plate 40. The slot 50 is arcuate having a radius equal to the distance of the centre of the pin 48 from the centre of the rotational mount 46. A hydraulic cylinder 52 is mounted to the rear face of the rear carriage plate 38. The proximal fixed end of the cylinder 52 is secured to the rear face of the rear carriage plate 38 at a height corresponding to the base or inflection point of the arcuate slot 50 and laterally spaced from the slot 50. The proximal end 54 of the cylinder 52 is rotationally mounted to the rear carriage plate 38. The opposing distal end 56 is rotationally mounted to the pin 48.

[0049] Linear extension or retraction of the cylinder 52 causes corresponding pulling or pushing motion on the pin 48. This causes the front carriage plate 40 to rotate about the rotational mount 46 with the pin 48 sliding in an arcuate motion within the slot 50 which acts to guide and restrain the pin 48 during movement. As the point of actuating engagement in the form of the pin 48 is spaced from the rotational mount 46 defining the pivot axis, a linear actuator is able to be used to provide a rotational movement. The spacing of the pin 48 from the pivot axis defines a moment arm, and due to the pin being substantially spaced across the carriage plate from the pivot axis the actuating force required to rotate the plate is minimised due to the moment arm being maximised. As such significantly less power is required than would be necessary if a direct rotational force were to be applied to the carriage plates, for example via a rotational drive shaft.

[0050] A vehicle attitude sensor (not shown) is provided that is mounted to the truck 2. The vehicle attitude sensor is arranged to detect both the lateral and fore and aft attitude of the truck 2, and may be any device suitable for determining this information. Preferably the attitude sensor includes at least one gyroscope and at least one accelerometer, and more preferably the attitude sensor includes a plurality of accelerometers and a plurality of gyroscopes. When the truck 2 is in a transversely and longitudinally horizontal attitude the front carriage plate 40 and the rear carriage plate 38 are aligned such that load sections 32 of the forks 30 are horizontal and parallel to the ground. The output signal from the vehicle attitude sensor is provided to a controller. When the controller determines that the lateral attitude of the truck 2 is not horizontal, based on the signal from the vehicle attitude sensor, the controller provides a signal to a hydraulic valve block connected to the hydraulic supply line to the hydraulic cylinder 52. The controller controls the cylinder 52 move and rotate the front carriage plate 40 relative to the rear carriage plate 38 to maintain front carriage plate 40 and hence the fork 32 in a horizontal attitude. The degree and direction to which front carriage plate 40 is rotated by the cylinder 52 is determined by the controller with the controller controlling the hydraulic valve block to extend or retract the cylinder 52 accordingly.

[0051] The vehicle attitude sensor also detects the horizontal attitude of the truck 2 in the longitudinal fore and aft direction. The controller is also connected to the cylinders 18 to control rotational movement of the mast assembly 14 to vary the fore and aft attitude of the mast assembly 14. The controller is therefore able to pivot the mast assembly forwardly or rearwardly in response to a change in the longitudinal horizontal attitude of the truck to maintain the horizontal attitude of the forks 30.

[0052] The attitude sensors in the control module are able to detect very minute changes in the attitude of the fork lift truck. When such a change is detected by the sensors the controller sends a control signal to the relevant actuators to cause the actuators to alter the attitude of the forks accordingly to maintain a level attitude of the load. This is a constantly updating process and only the averaged angle of lean determined from the sensors is used to provide hysteresis damping to prevent the actuators from jittering due to overly rapid response.

[0053] Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.