GB2550204A

GB2550204A - Method for operating a dump truck

Info

Publication number: GB2550204A
Application number: GB1608434.5A
Authority: GB
Inventors: Thompson Stephen
Original assignee: Caterpillar SARL
Current assignee: Caterpillar SARL
Priority date: 2016-05-13
Filing date: 2016-05-13
Publication date: 2017-11-15
Anticipated expiration: 2036-05-13
Also published as: GB2550204B; GB201608434D0

Abstract

A method of safely performing maintenance on a dump truck, by detecting that the body 14 has been raised to an angle β, preferably 20-72 degrees, then instructing the hydraulic system to reduce the pressure from a first value to a second value. Should the body fall by more than a set value, preferably 3-7 degrees, then the hydraulic system is instructed to increase pressure again, to prevent accidents. There may also be provided a securing device 30, which may comprise an elongate support prop having first and second engaging portions, 32, 36 (both shown in fig. 3) at either end which engage with the frame 12 and dump body 14 respectively. Also disclosed are a dump truck which performs this method and a computer program for performing this method.

Description

METHOD FOR OPERATING A DUMP TRUCK

Technical Field

The present disclosure relates to a dump truck, a method for operating a dump truck and a computer program product thereof.

Background

Dump trucks are widely used for transporting various materials, such as sand, gravel, dirt, etc. for a variety of applications. A dump truck has a dump body that is supported on a base frame, and can pivot so as to enable one end of the dump body to be elevated for purposes of discharging materials contained therein. Hydraulic cylinders (also called hydraulic actuators) are typically used to raise or lower the dump body with respect to the base frame.

During maintenance, the dump body may need positioning at a raised position with respect to the base frame. A support pin may be used to secure the dump body in this raised position so that relative movement between the dump body and base frame is substantially reduced or prevented. As such, the pin is typically designed to withstand the relative forces between the dump body and base frame, in addition to maximum hydraulic cylinder extend and retract forces (i.e. forces used to respectively raise and lower the dump body with respect to the base frame). In order to withstand these forces, the pin is manufactured to be a large and heavy structure. As a consequence, the pin may be cumbersome for an operator to install. Furthermore, the heavy structure of the pin tends to increase machine weight and production cost. Installation of the pin may require several persons. For example, one person may be required to control the positioning of the dump body with respect to the base frame and one or more additional persons may be required to lift and install the lock mechanism. JP Patent 2001/105958A, hereinafter referred to as ’958 reference, discloses preventing a body from being lowered when the body is in raised position using a pin.

Summary of the Disclosure

According to a first aspect of the present disclosure, there is provided a method for operating a dump truck comprising a frame, a dump body pivotably coupled to the frame and a hydraulic system for controlling movement of the dump body with respect to the frame, the method comprising: reducing a hydraulic system pressure from a first pressure value to a second pressure value based on a determination that the dump body has been maintained at a predetermined angle with respect to a longitudinal axis of the frame for a predetermined time period.

According to a second aspect of the present disclosure, there is provided a dump truck comprising: a frame; a dump body pivotably coupled to the frame; a hydraulic system for controlling movement of the dump body with respect to the frame; and a controller configured to cause a reduction of hydraulic system pressure from a first pressure value to a second pressure value based on a determination that the dump body has been maintained at the predetermined angle for a predetermined time period.

According to a third aspect of the present disclosure, there is provided a computer program product comprising a computer-readable medium comprising a set of instructions, which, when executed by a computer associated with a dump truck having a frame, a dump body pivotably coupled to the frame and a hydraulic system for controlling movement of the dump body with respect to the frame, causes the computer to: reduce a hydraulic system pressure from a first pressure value to a second pressure value based on a determination that the dump body has been maintained at a predetermined angle with respect to a longitudinal axis of the frame for a predetermined time period.

Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.

Brief Description of the Drawings FIG. 1 is a side view of a dump truck according to an exemplary embodiment of the present disclosure; FIG. 2 is a side view of the dump truck of Fig. 1 with the dump body being in a raised position and a service lock being provided; FIG. 3 is a front view of the service lock of Fig. 1 according to an exemplary embodiment of the present disclosure; FIG. 4 is a flowchart illustrating a method for installing a service lock according to an exemplary embodiment of the present disclosure; FIG. 5 is a perspective view of the dump truck of Fig. 1 showing an alternative service lock being provided;

Detailed Description

The present disclosure provides a method and system for controlling hydraulic pressure in a hydraulic system of a vehicle having a hydraulically controlled body associated with the vehicle. In particular, the method sets out a control strategy for selectively reducing and increasing hydraulic pressure based on whether or not a service operation is being performed on the vehicle. For example, the hydraulic pressure may be reduced when a securing apparatus, such as a service lock, is being used to aid securing the body in place during the service operation. The hydraulic pressure may be restored when the service operation has been completed and the service lock has been removed. The hydraulic pressure may be controlled in an automatic manner (without any direct operator inputs instructing a reduction or restoration of hydraulic pressure).

Referring to FIG. 1, there is provided a vehicle such as a dump truck 10. The dump truck 10 comprises a frame 12 and a dump body 14 coupled to the frame 12 in a pivotable manner. The dump truck 10 comprises a hydraulic system 16 for controlling movement of the dump body 14 with respect to the frame 12. A controller 18 is provided in association with the dump truck 10 and is for controlling the hydraulic system pressure. More particularly, the controller 18 is configured to cause a reduction of hydraulic system pressure from a first pressure value to a second pressure value based on a determination that the dump body 14 has been maintained at a predetermined angle for a predetermined time period.

According to an exemplary embodiment of the present disclosure, as shown in Fig. 1, the dump truck 10 may comprise a front section 20 and a rear section 22. The front section 20 and the rear section 22 may be coupled to one another in a manner in which the front section 20 may articulate with respect to the rear section 22. The front section 20 may be coupled to the rear section 22 via a hitch 24. The rear section 22 may comprise the aforementioned frame 12 and the dump body 14.

The hydraulic system 16 may comprise at least a control valve 26 and one or more hydraulic actuators 28. The hydraulic actuators 28 may be hydraulic cylinders such as is known in the art, for example, double-acting single-rod cylinders, and other such cylinder and piston arrangements. The hydraulic actuators may be disposed between the frame 12 and the dump body 14, and may be configured to control the movement of the dump body 14 with respect to the frame 12. The hydraulic actuators 28 may be used to raise and lower the dump body 14 with respect to the frame 12. In this regard, the dump body 14 may be lowered so that it rests on the frame (as shown in Fig. 1) and is suitable for receiving a load, raised for dumping/tipping the load (refer to dashed lines in Fig. 2), and raised to a position to allow a service operation to be carried out (see Fig. 2), for example, for maintenance of the dump truck 10.

Fig. 2 shows the dump truck 10 of Fig. 1 whereby the dump body 14 has been raised to a predetermined elevated position.

The position of the dump body 14 shown in dashed lines is one of a number of predetermined positions for performing a dumping operation. The angle of the dump body 14 with respect to the longitudinal axis X of the dump truck 10 and/or frame 12 is depicted by a.

The position of the dump body 14 shown in solid lines is one of a number of predetermined positions for performing a service operation. The angle of the dump body 14 with respect to the longitudinal axis X of the dump truck 10 and/or frame 12 is depicted by β. This may also be termed the “body lock angle”. The body lock angle β may take any value in a range of 15 to 90 degrees. The body lock angle may, in particular, take any value in a range of 20 to 72 degrees. For example, the body lock angle may be set at 72 degrees. A securing apparatus 30 may be provided to aid the securing of the dump body 14 in its raised position for service or maintenance. In this example, the securing apparatus 30 acts as a support device to assist maintaining the dump body 14 in its position.

As shown in more detail in Fig. 3, the securing apparatus 30 may comprise an elongate structural support 31, a support platform 32 at a first end 34 of the structural support 31 and a base platform 36 disposed at a second, opposing end 38 of the structural support 31. The securing apparatus 30 may further comprise a support strut 33 disposed between the structural support 31 and the base platform 33 that acts to strengthen the structural integrity of the securing apparatus 30. The securing apparatus 30 may be designed so that the support platform 30 is angled with respect to the base platform 33 at the body lock angle β. The securing apparatus 30, when installed in the dump truck 10, may be located towards a centre point of the frame 12 and between the frame 12 and underside of the dump body 14. In this manner, the base platform 36 may rest or engage an upper surface of the frame 12 and the support platform 32 may engage or support the underside of the dump body 14. As such the securing apparatus 30 may sometimes be referred to as a “body prop”.

Referring back to Figs 1 and 2, the dump truck 10 may comprise one or more sensors 44 for determining characteristics of the dump truck 10, such as angle of the dump body 14 with respect to the longitudinal axis X. For example, the sensor 44 may be an inertial measuring unit (IMU). Alternatively, another sensor may be used such as a rotary potentiometer or a linear transducer. The one or more sensors may measure other vehicle characteristics such as machine tractor and trailer roll angles, machine on grade (hill) angle and rate of steering for traction control. The body mounted IMU may also be used to signal to the payload system when loading is starting.

The controller 18 may be an electronic control module (ECM). The control valve 26 may be electronically controlled by the controller 18 so that it may provide a variable hydraulic pressure. In particular, for example, a proportional flow of hydraulic fluid may be provided and a relief pressure control capability may also be provided.

Electronic control over the control valve 26 allows for a decreased pressure setting to be applied to the actuator hydraulic control circuit. The decreased pressure may act to minimize a force exerted by the hydraulic actuator 28 when a securing apparatus 30 is installed. A graphical user interface (GUI) 46 may be provided so that an operator can interact with the dump truck 10. For example, the operator may use the GUI 46 to input commands or instructions to the dump truck 10 in order to perform a particular operation or function. The commands/instructions may be communicated to the controller 18, which may then interpret the instructions and then cause the relevant operation to be performed.

As an example, an option may be available to the operation for performing a service operation of the machine. In this regard, upon receiving the instructions from the operator, the controller 18 may send a signal to change the operations of the control valve 26 so as to vary the flow of hydraulic fluid within the hydraulic system 16, thereby causing the hydraulic actuators 28 to extend or retract.

The one or more sensors 44 may provide angular information about the dump body 14 with respect to the frame 12 to the controller 18. The controller 18 may use this information to control operations of the dump truck 10. In the example where the sensor 44 may be an IMU, the sensor 44 may comprises a three axes accelerometer and a gyroscope to measure acceleration and orientation of the dump body 24 in the three orthogonal axes (not shown).

The controller 18 is in communication with the one or more sensors 44. In addition to causing raise and lower operations, the controller 18 may additionally cause a change in hydraulic system pressure based on body lock angle β and related information.

For example, if the controller 18 has determined that the dump body 14 has been at the body lock angle β (with a programmable angular tolerance, for example, +/-1 degree) for a predetermined time period that is greater than a programmable threshold time period, then the controller 18 may cause the hydraulic system pressure to be reduced from a first pressure value to a second pressure value. The first pressure value and second pressure value may be predetermined. The threshold time period may be, for example, 30 seconds, 60 seconds or 120 seconds.

Once the hydraulic system pressure has been reduced to the second pressure value, the hydraulic system pressure is maintained at that second pressure value. A flag may be set at the controller to indicate that the dump body 14 is at the body lock angle β and that the hydraulic system pressure has been reduced.

The controller 18 may continue to monitor sensed angle information received from the one or more sensors 44. If there is a change in angular position of the dump body 14 from the body lock angle β by a predetermined amount, the controller 18 may cause the hydraulic system pressure to be restored to the first pressure value. For example, the predetermined amount may be an angle selected from a range of 3 to 15 degrees. The angle may be selected from a range of 3 to 7 degrees. The predetermined amount may be a tolerance so that the restoration may be triggered by both a positive (i.e. dump body 14 being raised from the body lock angle β) and negative (i.e. dump body 14 being lowered from the body lock angle β) change in angular position or alternatively, the predetermined amount may be in a single direction so that the restoration may be triggered only if the change in angular position is positive or negative.

Industrial Applicability

The present disclosure provides a method and apparatus for allowing a change in hydraulic system pressure to occur when predetermined criteria have been satisfied. In particular, a reduction in hydraulic system pressure may allow a lighter structure to be used as a securing apparatus 30 when performing a service operation. The securing apparatus 30 may thus be able to withstand and prevent a lowering of the dump body 14 of the dump truck 10 under (reduced) hydraulic pressure.

The operation of the dump truck 10 will now be described with reference to FIG. 4.

At Step 100, the operator may select an option using the GUI 46 (Step 100) to initiate a service or maintenance operation. For example, the operator may select an option “Apply Service Lock”. Additionally and alternatively, the operator may be required to enter a pass code via the GUI 46 in order to proceed to enter any instructions.

At Step 102, in response to the operator input, the controller 18 determines that a maintenance operation is required and may accordingly send a signal to the control valve 26, instructing an adjustment in the control valve 26 so as to move the dump body 14 to the body lock angle β (also called a prop angle). The control valve 26 may move to a hold configuration so as to maintain the dump body 14 at the body lock angle β

The operator may install a securing apparatus 30, such as that shown in Fig. 3, between the frame 12 and the dump body 14. The securing apparatus 30 may be used to assist the support of the dump body 14 so as to reduce any strain on the hydraulic system and components of the dump truck 10 when the dump body 14 is being maintained at the body lock angle β. The operator may then perform the desired service operation and may remove the securing apparatus 30 when complete.

At Step 104, based on a determination that the dump body 14 has been at the body lock angle β for the predetermined time period, the controller 18 causes the hydraulic system pressure to be reduced from the first pressure value to the second pressure value. Accordingly, should a hydraulic operation be instructed to lower the dump body 14, the hydraulic pressure would be at the second pressure value, which is lower than the normal, first hydraulic pressure. Due to the presence of the securing apparatus 30, which is designed to withstand the hydraulic pressures acting at the second pressure value to lower the dump body 14, the securing apparatus may prevent the dump body 14 from being lowered. In particular, the securing apparatus 30 may be designed to prevent the dump body 14 from being lowered past the body lock angle β.

At Step 105, based on a determination that the dump body 14 has changed from the body lock angle β by a predetermined angle, the controller 18 may then cause the hydraulic system pressure to return to the first pressure value from the second pressure value. In particular, the pressure may be restored to the first pressure value responsive to a determination the dump body 14 has been lowered by the predetermined angle, however the pressure may not be restored to the first pressure value if it has been determined that the dump body 14 has been raised. The determination that the dump body 14 has been lowered may be indicative that the securing apparatus 30 is no longer present and that the service operation is no longer required. This may, for example, be initiated by the operator via the GUI 46 by selecting an option “Remove Service Lock”, which may allow the operator to perform dump body 14 raise and lower operations.

Whilst not shown in the figures, it will be appreciated that the controller 18 described herein may comprises one or more processors and one or more memories. The control strategies executable by the controller 18 may use a set of instructions that may be stored on a computer program product. The computer program product may comprise a computer-readable medium comprising the set of instructions, which, when executed by a computer associated with a dump tmck, may cause the method steps described with reference to FIG. 4 to be performed.

While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.

For example, in the above exemplary embodiment described herein with reference to FIGs 1-4, the reduction in hydraulic system pressure is based on the amount of time that the dump body 14 has been at the body lock angle β. Alternatively or in addition, there may be provided a securing apparatus sensor that may sense when the securing apparatus 30 is installed. In this example, the hydraulic system pressure may only be reduced based on an additional determination that the securing apparatus 30 is installed. Similarly, the hydraulic system pressure may only be restored, in this example, based on an additional determination that the securing apparatus 30 is no longer installed. In this manner, the hydraulic system pressure may not be reduced when no service apparatus 30 is installed and cannot be restored when the service apparatus 30 is installed.

In the above exemplary embodiment described herein with reference to FIGs 1-4, the support apparatus 30 is a body prop. However, it will be appreciated that the support apparatus 30 may take other alternative forms and the principles of the present disclosure are not intended to be limited to the support apparatus 30 depicted in FIG. 3. For example, with reference to FIG. 5, an alternative support apparatus 200 is shown. In this example, the support apparatus 200 comprises a pin, which is used towards the rear of the frame 12 of the dump truck 10. In particular, the dump truck 10 comprises a bracket module 202 that includes a dump body bracket 204 and a rear frame bracket 206, with receiving holes 208, 210 being provided in the dump body bracket 204. The frame bracket 206 is provided with an opening 212. During maintenance, when the dump body 14 is fixed at the body lock angle β, the dump body bracket 204 and the rear frame bracket 206 move such that the receiving holes 208, 210 and the opening 212 are aligned. The pin 200 may then be inserted inside the receiving holes 208, 210, and the opening 212 so as to secure the dump body 14 at the body lock angle β.

Whilst embodiments of the present disclosure have been described with respect to dump trucks, it will be appreciated that the teachings herein will be applicable to any machine or vehicle having a hydraulic system that operates to move a body with respect to a frame, and which requires lifting of the body to perform a service or maintenance operation.

Claims

Claims What is claimed is:

1. A method for operating a dump truck comprising a frame, a dump body pivotably coupled to the frame and a hydraulic system for controlling movement of the dump body with respect to the frame, the method comprising: reducing a hydraulic system pressure from a first pressure value to a second pressure value based on a determination that the dump body has been maintained at a predetermined angle with respect to a longitudinal axis of the frame for a predetermined time period.

2. A method according to claim 1, comprising, based on a determination that the dump body has changed position from the predetermined angle by a predetermined value, restoring the hydraulic pressure to the first pressure value.

3. A method according to claim 2, wherein the predetermined value is a value selected from a range of 1 to 15 degrees and preferably, 3 to 7 degrees.

4. A method according to any preceding claim, wherein the predetermined angle is an angle selected from a range of 15 to 90 degrees and preferably, 20 to 72 degrees.

5. A method according to any preceding claim, wherein the predetermined time period is greater than 30 seconds, and preferably greater than 60 seconds, and more preferably, greater than 120 seconds.

6. A method according to any preceding claim, comprising, prior to reducing the hydraulic system pressure, positioning the dump body at the predetermined angle.

7. A method according to any preceding claim, comprising: providing a securing device between the dump body and the frame so as to secure the dump body at the predetermined angle.

8. A dump truck comprising: a frame; a dump body pivotably coupled to the frame; a hydraulic system for controlling movement of the dump body with respect to the frame; and a controller configured to cause a reduction of hydraulic system pressure from a first pressure value to a second pressure value based on a determination that the dump body has been maintained at the predetermined angle for a predetermined time period.

9. A dump truck according to claim 8, wherein the controller is configured to cause a restoration of the hydraulic system pressure to the first pressure value based on a determination that the dump body has changed position from the predetermined angle by a predetermined value.

10. A dump truck according to claim 9, wherein the predetermined value is a value selected from a range of 3 to 15 degrees and preferably, 3 to 7 degrees.

11. A dump truck according to any of claims 8 to 10, wherein the predetermined angle is an angle selected from a range of 30 to 90 degrees and preferably, 60 to 80 degrees.

12. A dump truck according to any of claims 8 to 11, wherein the predetermined time period is greater than 30 seconds, and preferably greater than 60 seconds, and more preferably, greater than 120 seconds.

13. A dump truck according to any of claims 8 to 12 comprising: a removable securing device adapted to be placed between the dump body and the frame so as to secure the dump body at the predetermined angle.

14. A dump truck according to claim 13, wherein the securing device comprises an elongate structural support prop having a first engaging portion at a first end and a second engaging portion disposed at a second, opposing end.

15. A dump truck according to claim 14, wherein the frame comprises a first adaptor portion configured to receive the first engaging portion of the elongate structural support, and wherein the dump body comprises a second adaptor portion configured to receive the second engaging portion of the elongate structural support.

16. A computer program product comprising a computer-readable medium comprising a set of instructions, which, when executed by a computer associated with a dump truck having a frame, a dump body pivotably coupled to the frame and a hydraulic system for controlling movement of the dump body with respect to the frame, causes the computer to: reduce a hydraulic system pressure from a first pressure value to a second pressure value based on a determination that the dump body has been maintained at a predetermined angle with respect to a longitudinal axis of the frame for a predetermined time period.

17. A computer program product according to claim 16, wherein the set of instructions, when executed by the computer cause the computer to restore the hydraulic pressure to the first pressure value, based on a determination that the dump body has changed position from the predetermined angle by a predetermined value.

18. A computer program product according to claims 16 or 17, wherein the predetermined value is selected from a range of 3 to 15 degrees and preferably, 3 to 7 degrees.

19. A computer program product according to any one of claims 16 or 18, wherein the predetermined angle is an angle selected from a range of 30 to 90 degrees and preferably, 60 to 80 degrees.

20. A computer program product according to any one of claims 16 or 19, wherein the predetermined time period is greater than 30 seconds, and preferably greater than 60 seconds, and more preferably, greater than 120 seconds.