Articulated work vehicles

Abstract

The invention relates to a work machine vehicle provided with a supporting frame and a pivotable loading container, wherein the vehicle is configured to allow tilting of the loading container from a transport position to a tilted position, wherein the vehicle is provided with a suspension arrangement, wherein the suspension arrangement comprises a spring element and a damping element, and wherein the vehicle is further provided with at least one hydraulic lifting cylinder connected between the frame and the loading container and arranged to lift and tilt the loading container to a dumping position. The hydraulic lifting cylinder forms part of a hydraulic system comprising a container for a hydraulic fluid and at least one conduit connecting the hydraulic lifting cylinder with the container to form a flow path for the hydraulic fluid between the hydraulic lifting cylinder and the hydraulic container, and wherein the flow path is arranged to apply a flow resistance to the hydraulic fluid flowing through the flow path to damp an oscillating flow through the flow path, thereby forming a damping element of the suspension arrangement.

Description

Technical Field

[0001] The present invention relates to a work machine vehicle, such as an articulated hauler, provided with a suspension arrangement configured to reduce the transmission of vibrations between the vehicle frame and a loading container. Background Art

[0002] An articulated work machine vehicle comprises a front vehicle portion and a rear vehicle portion which are pivotally connected by a connection arrangement which is configured to control the pivot angle between the front and rear portions for steering of the vehicle. The rear vehicle portion of an articulated transporter is usually provided with a tiltable loading container (sometimes referred to as a "body") which is arranged on a supporting frame. When the loading container is in the transport (lower) position and sits on the frame, vibrations may be transmitted between the frame and the loading container. Such vibrations may increase wear on the vehicle and / or may affect the comfort of the driver in the cab of the front portion.

[0003] Rubber supports may be arranged between the frame and the loading container, but such rubber supports do not reduce the vibration transmission in an effective manner.

[0004] US 2015 / 0159729 A1 discloses a suspension assembly for a payload carrier, the suspension assembly comprising various plates and elements forming dampers and springs for the purpose of reducing the transmission of vibrations to the payload carrier.

[0005] CN105966474 discloses an active vibration reduction support system for a mining dump truck, including a spring, a damper, a sensor, an actuator, an optimization calculation module, etc., to provide, for example, active adjustment of vibration reduction capability.

[0006] There is a need for a less complex load container suspension arrangement. In particular, there is a need for a load container suspension arrangement suitable for articulated vehicles. Summary of the invention

[0007] The present disclosure relates to a work machine vehicle provided with a support frame and a pivotable loading container, wherein the vehicle is configured to allow the loading container to be tilted from a transport position to a tilted position for dumping a load from the loading container. The vehicle is provided with a suspension arrangement configured to reduce the transmission of vibrations between the frame and the loading container when the loading container is in its transport position. The suspension arrangement comprises a spring element and a damping element, and the vehicle is further provided with at least one hydraulic lifting cylinder connected between the frame and the loading container and used to lift and tilt the loading container to the dumping position for dumping.

[0008] According to the present disclosure, the hydraulic lifting cylinder forms part of a hydraulic system comprising a container for hydraulic fluid and at least one conduit connecting the hydraulic lifting cylinder with the container to form a flow path for the hydraulic fluid between the hydraulic lifting cylinder and the hydraulic container. The flow path is arranged to apply a flow resistance to the hydraulic fluid flowing through the flow path to damp an oscillating flow through the flow path, thereby forming a damping element of the suspension arrangement.

[0009] That is, if the stowage container vibrates relative to the frame, hydraulic fluid is forced to flow back and forth through the flow passage and the vibrations are damped due to flow resistance, which may be caused by conduit diameter, bends, and / or orifices.

[0010] A damping element is thus formed which makes use of the hydraulic lifting cylinders which are usually present anyway on articulated haulers or similar vehicles. Furthermore, suitable hydraulic systems are usually also already present on at least articulated vehicles for vehicle steering and for operating the lifting cylinders, so that only some adaptations of the usually existing components are required to form the damping element of the above-mentioned suspension arrangement. Such already existing hydraulic systems are usually very robust systems, which also makes the damping element very suitable for articulated haulers as well.

[0011] The suspension arrangement may be activated when the (empty) loading container is arranged in a "riding" position in which the loading container is in its transport position but at a short distance from the supporting surface of the frame.

[0012] Compared to US 2015 / 0159729 A1 and CN 105966474, the disclosed suspension arrangement is less complex and requires fewer additional components, since (hydraulic) components that are already present at least on most articulated vehicles are used for vibration damping.

[0013] In one embodiment, the hydraulic container is a closed accumulator, which is partially filled with gas to act as a spring for the oscillating flow of hydraulic fluid and thereby forms a spring element of the suspension arrangement. The closed gas provides compression and expansion and can thus act as a spring. In this case, the hydraulic system is therefore also used to realize the elastic function. Additional spring elements can be used as a supplement, such as mechanical helical coil springs. When the (empty) loading container is set in the "riding" position, the accumulator can be connected to the piston chamber side of the lifting cylinder.

[0014] In one embodiment, the hydraulic container is an open tank, wherein a first conduit connects the open tank with the high pressure side of the hydraulic lifting cylinder, wherein a second conduit connects the open tank with the low pressure side of the hydraulic lifting cylinder, and wherein the hydraulic lifting cylinder is configured to be set in a suspended state in which a hydraulic fluid can flow through the hydraulic lifting cylinder between the high pressure side and the low pressure side, wherein the flow path for the hydraulic fluid forms a circuit, the circuit comprising the open tank, the first conduit, the hydraulic lifting cylinder and the second conduit, through which the hydraulic fluid can flow in either direction, thereby forming a damping element of the suspension arrangement. Also in this case, the flow resistance may be generated by conduit diameter, bends and / or orifices, but the flow resistance may additionally or alternatively be generated in the hydraulic lifting cylinder, such as at the connection between the high pressure side and the low pressure side.

[0015] In one embodiment, the flow passage for the hydraulic fluid is provided with orifices to increase the flow resistance to a suitable level. What level is suitable depends on the particular application.

[0016] In one embodiment, the suspension arrangement comprises a spring element in the form of at least one mechanical spring. This is of course particularly noteworthy for variants in which a hydraulic system is not used as spring element. A helical coil spring may be used.

[0017] In one embodiment, the suspension arrangement is configured to separate the natural vibration frequency of the vehicle. For an articulated vehicle comprising a front vehicle part and a rear vehicle part and the stowage container is arranged on the rear vehicle part, the natural vibration frequency is the natural vibration frequency of the rear vehicle part.

[0018] By introducing suitable spring and damping elements to the loading container / body, the dynamic characteristics of the vehicle or the rear vehicle part / loading unit are modified. With the standard bogie suspension of an articulated hauler, the loading unit has a unique natural frequency which corresponds to the bounce on the rear wheels and is related to the pitch of the entire vehicle / transporter. By introducing the suspended body, the single natural frequency is split into two separate frequencies; a lower own / eigenfrequency of the body and an increased eigenfrequency of the rest of the loading unit. In addition, the rear frame displacement amplitude is reduced, which in turn reduces the cab displacement caused by the vehicle pitching motion. The natural frequency to be concerned about preventing may vary depending on the type of dynamic characteristics of different machine types. For a typical articulated hauler, the natural frequency corresponding to rear wheel bounce is about 2 Hz (for an empty body / loading container).

[0019] The natural eigenfrequency of the rear vehicle part / loading unit of interest to be damped out can be denoted as "f". To achieve this, the body / loading container is suspended (in its "riding" position) in a spring suspension arranged so that the body / loading container acquires an eigenfrequency "f". This splits the previous single natural frequency into two eigenfrequencies; the higher of the two frequencies excites the loading unit / rear vehicle part (now without the body mass), while the lower of the two frequencies excites both the loading unit / rear vehicle part and the body / loading container (now the damped frequency).

[0020] The spring stiffness "k" is appropriately selected so that the body eigenfrequency corresponds to the frequency desired to be damped, i.e., for example, a frequency of 2 Hz. The spring stiffness can be obtained by the following expression:

[0021] k=(2πf) 2 (I0+mr 2 )+mgrsin(α0+α)

[0022] in

[0023] k: rotational stiffness around the body (loading container) hinge,

[0024] f: Pay attention to the frequency of prevention,

[0025] I0: moment of inertia around the cog (center of gravity) of the body,

[0026] m: the mass of the empty body,

[0027] r: distance from the body hinge to the body cog,

[0028] g: gravitational constant,

[0029] α0: lowers the angle of the subject relative to the subject cog,

[0030] α: The angle of the lowered body cog relative to the body cog in static equilibrium supported by the spring.

[0031] Since both mechanical springs and gas springs (hydraulic accumulators) which are usually arranged at the front edge of the body / loading container can be used, it is convenient to express the spring rate as the rotational stiffness about the body hinge. For a typical articulated hauler, the rotational stiffness k may be of the order of 110 kNm / degree. A useful interval may be, for example, 100-120 or 90-130 kNm / degree, depending on the vehicle.

[0032] A relative damping (damping ratio) of about 0.3-0.4 of the spring suspension body may be suitable. The damping can be calculated by the following expression:

[0033] c=ζ2Iω n

[0034] in

[0035] c: damping of the system,

[0036] ζ: damping ratio,

[0037] I: the moment of inertia of the body around the body hinge,

[0038] ω n : Natural frequency of the suspension body.

[0039] The damping amplitude may be around 350kNs / m.

[0040] The suspension arrangement is configured to separate the natural vibration frequencies of the rear vehicle part, which therefore means that the spring stiffness "k" is adapted to the specific vehicle (e.g. to the mass of the empty body / loading container) and is chosen so that the natural vibration frequencies of the rear vehicle part are at least partially damped.

[0041] In one embodiment, the spring element is configured to maintain the empty loading container at a specified distance above the support surface of the frame when the loading container is set in its transport position. This is thus the "riding" position mentioned above. Maintaining a short distance between the loading container and the frame support surface allows for a downward stroke of the spring element. This distance may be about 10-20 cm (at the front portion of the loading container opposite the hinge).

[0042] In one embodiment, the hydraulic lifting cylinder includes a piston, a piston rod, a piston side chamber and a piston rod side chamber.

[0043] In one embodiment, the vehicle is provided with two hydraulic lifting cylinders, one on each side of the loading container.The two hydraulic lifting cylinders may be connected to the same hydraulic container.

[0044] In one embodiment, the vehicle is an articulated work machine vehicle, such as an articulated hauler, comprising a front vehicle portion and a rear vehicle portion, the front vehicle portion and the rear vehicle portion being pivotally connected by a connection arrangement configured to control a pivot angle between the front portion and the rear portion for steering of the vehicle. Preferably, the support frame and the pivotable loading container are provided on the rear vehicle portion.

[0045] In an embodiment relating to an articulated work machine vehicle, the suspension arrangement is configured to separate the natural vibration frequency of the rear vehicle portion. In such an embodiment, the natural vibration frequency of the rear vehicle portion may be "f", and the spring stiffness of the spring element may be such that when expressed as the rotational stiffness "k" about the loading container hinge, the spring stiffness satisfies the same expression as given above, namely:

[0046] k=(2πf) 2 (I0+mr 2 )+mgrsin(α0+α).

[0047] Further advantages and advantageous features of the invention are disclosed in the following description and in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Embodiments of the invention cited as examples are described in more detail below with reference to the accompanying drawings.

[0049] In the attached picture:

[0050] Figure 1 An articulated hauler is shown provided with a schematically depicted first embodiment of a suspension arrangement according to the present disclosure.

[0051] Figure 2 An articulated hauler is shown provided with a schematically depicted second embodiment of a suspension arrangement according to the present disclosure.

[0052] Figure 3 A schematic diagram of a loading container and some parameters used to calculate a suitable rotational stiffness is shown. DETAILED DESCRIPTION

[0053] Figure 1 A work machine vehicle in the form of an articulated hauler 1 is shown. The vehicle 1 comprises a front vehicle part 2 (front unit) and a rear vehicle part 3 (loading unit) pivotally connected by a connection arrangement 4 for controlling the pivot angle between the front part 2 and the rear part 3 for steering of the vehicle 1. The rear vehicle part 3 is provided with a supporting frame 6 and a pivotable loading container 5 (body). The vehicle 1 is configured to allow the loading container 5 to be lifted from a transport position (such as a loading position) by means of a pair of hydraulic lifting cylinders 9 (one hydraulic lifting cylinder 9 on each side of the loading container 5). Figure 1 The front vehicle part 2 is tilted to a tilted position for dumping the load from the loading container 5. The cab is arranged on the front vehicle part 2. A pair of wheels 7 is arranged on the front vehicle part 2 and two pairs of wheels 8 are arranged on the rear part 3. The vehicle 1 further comprises a hydraulic system, for example for controlling the pivot angle and steering the vehicle and for extending the lifting cylinder 9 for dumping.

[0054] Figure 1Further shown is a first example of a vehicle 1 provided with a suspension arrangement 20 configured to reduce the transmission of vibrations between the frame 6 and the loading container 5 when the loading container 5 is in its transport position. It should be noted that the suspension system 20 is only Figure 1 Schematically depicted in .

[0055] The suspension arrangement 20 comprises spring elements and damping elements and is in this example a fully hydraulic system, comprising: a hydraulic lifting cylinder 9; a container for hydraulic fluid in the form of a closed accumulator 11 and partly filled with a gas 11b; and a conduit 10 connecting the piston side chamber 9a (i.e. the high pressure side) of the hydraulic lifting cylinder 9 with the accumulator 11. The conduit 10 thus forms a flow path for the hydraulic fluid between the piston side chamber 9a of the hydraulic lifting cylinder and the accumulator 11. The flow path / conduit 10 is provided with an orifice 12 to increase the flow resistance to the hydraulic fluid flowing through the flow path 10.

[0056] Although in Figure 1 Not visible in the figure, but the (empty) loading container 5 is arranged in a “riding” position in which it is in its transport position but at a small distance from the supporting surface of the frame 6 to allow upward and downward vibrating movements relative to the frame 6.

[0057] When the stowage container 5 moves (vibrates) relative to the frame 6, the hydraulic fluid is forced to flow through the flow passage / conduit 10, and the movement (vibration) is damped due to the flow resistance provided by the orifice 12. In this case, when the stowage container 5 vibrates relative to the frame 6, the hydraulic fluid flows back and forth through the flow passage / conduit 10 in an oscillating manner.

[0058] Since the hydraulic accumulator 11 is a closed container which is partly filled with gas 11 b and partly filled with hydraulic fluid 11 a and since the gas can be compressed and then expanded, the accumulator 11 acts as a spring for the oscillating flow of the hydraulic fluid and thereby forms a spring element of the suspension arrangement 20 .

[0059] Figure 1 Also shown is an open tank 12 and another conduit 13 connecting the open tank 12 with the piston rod side chamber 9b of the lifting cylinder 9. The open tank 12 serves as a reservoir for hydraulic fluid during normal lifting operation of the hydraulic lifting cylinder 109. Yet another conduit (not shown) connects the open tank 12 with the piston side chamber 9a of the cylinder 109.

[0060] Figure 2 Shown with Figure 1The vehicle 1 is similar to the vehicle 1 of the embodiment of the present invention, but in this case the vehicle 1 is provided with a second example of a suspension arrangement 120, which is configured to be able to move when the loading container 5 is in its transport position (in particular when arranged in its "riding" position, similar to the vehicle 1 of the embodiment of the present invention). Figure 1 As described above, the vibration transmission between the frame 6 and the loading container 5 is reduced. It should also be noted that Figure 2 In the example shown, the suspension system 120 is depicted only schematically.

[0061] like Figure 2 As shown, the hydraulic reservoir is now an open tank 112. A first conduit 110 connects the open tank 112 to the piston side chamber 109a of the hydraulic lifting cylinder 109, and a second conduit 113 connects the open tank 112 to the piston rod side chamber 109b of the hydraulic lifting cylinder 109. The hydraulic lifting cylinder 109 is configured to be arranged in a suspended state, in which the hydraulic fluid can flow through the hydraulic lifting cylinder 109 between the piston side chamber 109a and the piston rod side chamber 109b. Therefore, in this example, the restricted flow path for the hydraulic fluid forms a circuit, which includes the open tank 112, the first conduit 110, the hydraulic lifting cylinder 109 and the second conduit 113, and the hydraulic fluid can flow through the circuit in either direction to form a damping element of the suspension arrangement 120. In this case, the flow restriction is caused by the flow friction of the hydraulic fluid when it flows through the lifting cylinder 109. If this flow friction is not sufficient to achieve the required damping effect, the orifice ( Figure 2 ) is arranged between the tank 112 and the cylinder 109.

[0062] When the loading container 5 vibrates relative to the frame 6, the hydraulic fluid is also forced to flow back and forth through the flow passage circuit to and from the tank 112 in an oscillating manner in this case, and the vibrations are damped due to the flow resistance provided by friction (or orifices).

[0063] Figure 2 It is further shown that a second example of a suspension arrangement 120 comprises a spring element in the form of at least one mechanical spring 115 arranged between the frame 6 and the stowage container 5 .

[0064] In the above examples, the hydraulic lifting cylinders 9, 109 themselves are of a conventional type, in which a piston rod is connected to a piston, and in which the piston is able to move back and forth within the cylinder.

[0065] Figure 3 A schematic diagram of the loading container 5, frame 6, loading container hinge 22 is shown, as well as some parameters, namely the center of gravity 23 (cog) at different angles α, for calculating the appropriate rotational stiffness "k" about the loading container / body hinge 22. It should be noted that Figure 3It is just a schematic diagram, so cog23 is Figure 3 is not correctly indicated in Figure 3 more to the left of the center).

[0066] Each of the suspension arrangements 20, 120 is configured to separate the natural vibration frequencies of the rear vehicle portion 3. This is done by selecting the spring stiffness k so that the body eigenfrequency corresponds to the frequency that it is desired to separate and damp out, i.e., for example, a frequency of 2 Hz (see also further explanation above). In this example, the spring stiffness is derived from the following expression:

[0067] k=(2πf) 2 (I0+mr 2 )+mgrsin(α0+α)

[0068] in

[0069] k: rotational stiffness around the main body (loading container) hinge 22,

[0070] f: Pay attention to the frequency of prevention,

[0071] I0: moment of inertia of cog23 around body 5,

[0072] m: the mass of the empty body 5,

[0073] r: distance from body hinge 22 to cog 23 of body 5,

[0074] g: gravitational constant,

[0075] α0: lower the angle of body 5 relative to body cog23.

[0076] α: The angle of the lowered body cog relative to the body cog in static equilibrium supported by the spring.

[0077] Since both mechanical springs and gas springs (hydraulic accumulators) can be used, which are usually arranged at the front edge of the body / stowage container, it is convenient to express the spring rate as the rotational rate about the body hinge. Figure 1 and Figure 2 For an articulated hauler of the type illustrated in FIG. 1 , the rotational stiffness k is approximately 110 kNm / degree.

[0078] for Figure 1 and Figure 2 For an articulated transporter of the type illustrated in the example, a relative damping (damping ratio) of about 0.3-0.4 of the spring suspension body 5 is suitable. The damping can be calculated by the following expression:

[0079] c=ζ2Iωn

[0080] in

[0081] c: damping of the system,

[0082] ζ: damping ratio,

[0083] I: the moment of inertia of the main body 5 around the main body hinge 22,

[0084] ω n : The natural frequency of the suspension body 5.

[0085] For the example described here, a damping amplitude of approximately 350 kNs / m is suitable.

[0086] The hydraulic components of the suspension arrangement 20 , 120 may in practice be arranged in different ways and located at different locations on the vehicle.

[0087] It should be understood that the present invention is not limited to the embodiments described above and shown in the drawings; on the contrary, a person skilled in the art will recognize that many changes and modifications are possible within the scope of the appended claims.

Claims

1. A work machine vehicle (1), said vehicle (1) being provided with a support frame (6) and a pivotable loading container (5), wherein: The vehicle (1) is configured to allow the pivotable loading container (5) to be tilted from a transport position to a tilted position for dumping a load from the pivotable loading container (5), wherein the vehicle (1) is provided with a suspension arrangement configured to reduce the transmission of vibrations between the support frame (6) and the pivotable loading container (5) when the pivotable loading container (5) is in its transport position, wherein the suspension arrangement comprises spring elements and damping elements, and wherein the vehicle (1) is further provided with at least one hydraulic lifting cylinder connected between the support frame (6) and the pivotable loading container (5) and used to lift and tilt the pivotable loading container (5) to the dumping position for dumping, It is characterized in that the hydraulic lifting cylinder forming part of a hydraulic system comprising a hydraulic container for a hydraulic fluid and at least one conduit connecting the hydraulic lifting cylinder with the hydraulic container to form a flow path for the hydraulic fluid between the hydraulic lifting cylinder and the hydraulic container, and wherein the flow path is arranged to apply a flow resistance to the hydraulic fluid flowing through the flow path to damp an oscillating flow through the flow path, thereby forming the damping element of the suspension arrangement, wherein the suspension arrangement is configured to separate the natural vibration frequencies of the vehicle (1), wherein the natural vibration frequency is "f", and wherein the spring stiffness of the spring element is such that when expressed as a rotational stiffness "k" about the loading container hinge (22), the spring stiffness satisfies the following expression: in k: rotational stiffness around the loading container hinge (22), f: Pay attention to the frequency of prevention, I 0 : moment of inertia about the center of gravity (23) of the loading container, m: mass of the empty loading container, r: distance from the loading container hinge (22) to the center of gravity of the loading container (23), g: gravitational constant, : lowering the angle of the loading container relative to the center of gravity (23) of the loading container, : Lowering the angle of the center of gravity of the loading container relative to the center of gravity of the loading container in a static equilibrium state supported by the spring.

2. The vehicle (1) according to claim 1, wherein: The hydraulic container is a closed accumulator (11) which is partially filled with a gas (11b) to act as a spring for an oscillating flow of hydraulic fluid, thereby forming the spring element of the suspension arrangement.

3. The vehicle (1) according to claim 1, wherein: The hydraulic container is an open tank (112), wherein a first conduit (110) connects the open tank (112) to a piston side chamber of the hydraulic lifting cylinder, wherein a second conduit (113) connects the open tank (112) to a piston rod side chamber of the hydraulic lifting cylinder, and wherein the hydraulic lifting cylinder is configured to be arranged in a suspended state, in which the hydraulic fluid can flow through the hydraulic lifting cylinder between the piston side chamber and the piston rod side chamber, wherein the flow path for the hydraulic fluid forms a circuit, the circuit comprising the open tank (112), the first conduit (110), the hydraulic lifting cylinder and the second conduit (113), the hydraulic fluid can flow through the circuit in either direction, thereby forming the damping element of the suspension arrangement.

4. The vehicle (1) according to any one of claims 1 to 3, wherein: The flow passage for the hydraulic fluid is provided with at least one orifice (12).

5. The vehicle (1) according to any one of claims 1 to 3, wherein: The suspension arrangement comprises a spring element in the form of at least one mechanical spring (115).

6. The vehicle (1) according to any one of claims 1 to 3, wherein: The spring element is configured to hold an empty pivotable loading container (5) at a specified distance above a supporting surface of the supporting frame (6) when the pivotable loading container is arranged in its transport position.

7. The vehicle (1) according to any one of claims 1 to 3, wherein: The hydraulic lifting cylinder comprises a piston, a piston rod, a piston side chamber and a piston rod side chamber.

8. The vehicle (1) according to any one of claims 1 to 3, wherein: The vehicle (1) is provided with two hydraulic lifting cylinders, one on each side of the pivotable loading container (5).

9. The vehicle (1) according to any one of claims 1 to 3, wherein: The vehicle (1) is an articulated working machine vehicle (1) comprising a front vehicle portion (2) and a rear vehicle portion (3), wherein the front vehicle portion (2) and the rear vehicle portion (3) are pivotally connected via a connection arrangement (4), and the connection arrangement (4) is configured to control a pivot angle between the front vehicle portion (2) and the rear vehicle portion (3) for steering the vehicle (1).

10. The vehicle (1) according to claim 9, wherein: The supporting frame (6) and the pivotable loading container (5) are arranged on the rear vehicle part (3).

11. The vehicle (1) according to claim 10, wherein: The suspension arrangement is configured to separate the natural vibration frequencies of the rear vehicle portion (3).

12. The vehicle (1) according to claim 11, wherein: The natural vibration frequency of the rear vehicle part (3) is "f".

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