Cabin suspension for a commercial vehicle

Abstract

Cabin suspension for a commercial vehicle, comprising a load-bearing vehicle structure (14) and a driver's cab (16) which is spring-supported relative to the load-bearing vehicle structure (14), wherein bearing blocks (28, 30) are attached to a first side of the cab (26) relative to the load-bearing vehicle structure (14) and mechanical spring struts (34, 36) are articulated to a second side of the cab (32) relative to the load-bearing vehicle structure (14), characterized in that a mass (50) which can be displaced between the first and the second side of the cab (26, 32) by means of a control device (48) is provided for changing a zero position of the suspension of the mechanical spring struts (34, 36).

Description

[0001] The invention relates to a cabin suspension for a commercial vehicle with a load-bearing vehicle structure and a driver's cabin supported by springs relative to the load-bearing vehicle structure, wherein bearing blocks are provided on a first side of the cabin relative to the load-bearing vehicle structure and mechanical spring struts are articulated on a second side of the cabin relative to the load-bearing vehicle structure.

[0002] This type of cab suspension is known, for example, as MCS (Mechanical Cab Suspension) on John Deere agricultural tractors. The purely mechanical cab suspension comprises front cab mountings in the form of right and left rubber mounts, and rear cab mountings in the form of right and left mechanical shock absorbers. The cab suspension's natural frequency is tuned to a specific total weight of the cab. For optimal ride comfort, values ​​in the range of 1 Hz are ideal for wheeled vehicles; however, this results in a comparatively soft or yielding suspension characteristic. Depending on the driver's weight and the cab's equipment variant, this can lead to a noticeable shift in the suspension's neutral position and thus to a reduction in the available suspension travel at the mechanical shock absorbers.To accommodate all conceivable payload situations, and due to the generally limited adjustability of mechanical shock absorbers, the cabin suspension is therefore tuned to be correspondingly stiff in practice. The resulting ride comfort is thus merely a compromise.

[0003] It is therefore an object of the present invention to further develop a cabin suspension of the type mentioned above in such a way that optimal suspension comfort can be achieved with it regardless of the respective payload situation.

[0004] This problem is solved by a cabin suspension for a commercial vehicle with the features of claim 1.

[0005] The cab suspension for a commercial vehicle comprises a load-bearing vehicle structure and a driver's cab that is flexibly supported relative to the load-bearing vehicle structure. Bearing blocks are attached to the load-bearing vehicle structure on one side of the cab, and mechanical shock absorbers are articulated to the load-bearing vehicle structure on the other side. Furthermore, a mass, movable by means of a control device, is provided between the first and second sides of the cab to adjust the neutral position of the mechanical shock absorbers.

[0006] Shifting the mass allows for a change in the center of gravity between the first and second sides of the cab, thus enabling a targeted adjustment of the proportion of the cab's total weight acting on the mechanical shock absorbers. This makes it possible to adjust the suspension's neutral position so that the available travel at the mechanical shock absorbers during compression remains constant, regardless of the load. When the mechanical shock absorbers are relieved of weight, for example, due to a driver change, this can be achieved by shifting the mass, and therefore the center of gravity, of the cab towards the mechanical shock absorbers.Conversely, when the mechanical suspension struts are loaded, for example when a passenger gets in, the mass and thus the center of gravity of the driver's cab can shift towards the bearing blocks and away from the mechanical suspension struts. In both cases, the mass is shifted in such a way that the suspension's neutral position remains unchanged. The tuning of the suspension characteristics of the cab's mechanical suspension struts can therefore be adjusted, regardless of the specific load situation, to achieve optimal ride comfort.

[0007] The mechanical shock absorbers are of a conventional design and comprise two segments mounted to be longitudinally displaceable within each other, which are supported against each other by an intermediate coil spring.

[0008] Further advantageous embodiments of the cabin suspension according to the invention for a commercial vehicle are evident from the dependent claims.

[0009] Preferably, the mass is shifted by means of the control device in such a way that the proportion of the total weight of the driver's cab acting on the mechanical shock absorbers, and thus the selected natural frequency of the mechanical shock absorbers, remains constant in the event of a change in payload. For this purpose, the control device or a control unit comprised thereof calculates, based on load information acquired at the mechanical shock absorbers and / or a vehicle seat, a mass distribution achievable by varying the position of the shiftable mass, which is suitable for compensating for the effect of the change in total weight in the area of ​​the associated pivot points of the mechanical shock absorbers on the driver's cab.

[0010] The movable mass can be a mass body that can be shifted along a mechanical guide in the area between the first and second sides of the cab by means of an actuator integrated into the control unit. The mass body is, for example, a weight made of cast steel, which is mounted longitudinally in a guide rail attached to the driver's cab by means of a slide. An electric spindle drive integrated into the actuator allows the weight to be moved continuously back and forth along the guide rail between a first and a second end stop. However, instead of a separate weight, existing vehicle components can also be used as the mass body, such as a vehicle battery that can be shifted by means of the actuator, or similar components.

[0011] On the other hand, it is also conceivable that the displaceable mass is a liquid that can be pumped back and forth between a first and a second ballast tank by means of a pump integrated into the control unit, with the first ballast tank being located on the first side of the cab and the second ballast tank on the second side. Depending on which of the two ballast tanks contains the larger quantity of liquid, the center of gravity of the driver's cab shifts towards the first or second side. The liquid could, for example, be hydraulic oil from a hydraulic system installed in the commercial vehicle. However, any other liquids or fluidic materials could also be used.

[0012] Furthermore, the two ballast tanks inside can be segmented into a multitude of interconnected liquid chambers, so that movement of the liquid in the ballast tanks caused by driving can be dampened by utilizing the flow losses occurring between the liquid chambers. In this way, an undesirable shift in the center of gravity of the driver's cab caused by excessive liquid movement can be suppressed.

[0013] To determine the proportion of the total weight of the driver's cab acting on the mechanical suspension struts, the control unit or the control unit it comprises can determine the extent of the payload based on a load-change-induced displacement of the suspension's neutral position occurring at the mechanical suspension struts and / or on the weight of a person seated in the vehicle. The vehicle seat, equipped with appropriate load-sensing sensors, can be the driver's seat or, if applicable, a passenger seat. Furthermore, the detection of the suspension's neutral position can be performed either statically, i.e., when the vehicle is stationary, or dynamically while driving. For the latter, the deflections occurring at the mechanical suspension struts around their respective neutral positions are integrated or averaged over time.The displacement of the suspension's neutral position, taking into account the assumed known spring stiffness of the mechanical suspension struts, allows for the determination of the payload's extent. The control unit calculates this displacement by evaluating position information from multiple sensors that monitor the suspension's compression state.

[0014] From the load information obtained in this way, the control device or control unit derives a mass distribution achievable by appropriate shifting of the mass, which is suitable to compensate for the effect of the overall weight change in the area of ​​the pivot points of the mechanical suspension struts on the driver's cab.

[0015] Furthermore, it is conceivable that the displaceable mass is arranged centrally between the corresponding pivot points of the mechanical shock absorbers on the driver's cab, so that an even load on the mechanical shock absorbers is ensured.

[0016] To ensure sufficient stability of the commercial vehicle when tipping over, a low center of gravity is preferable. For this purpose, the displaceable mass can be located in the area of ​​the cabin floor, particularly underneath it.

[0017] The cabin suspension according to the invention is explained in more detail below with reference to the accompanying drawings. Components that are identical or comparable in function are marked with the same reference numerals. The drawings show: Fig. 1 a first embodiment of the cabin suspension according to the invention with a displaceable mass designed as a mass body, and Fig. 2 a second embodiment of the cabin suspension according to the invention with a displaceable mass designed as a liquid.

[0018] Fig. Figure 1 shows a first embodiment of the cabin suspension according to the invention for a commercial vehicle. The commercial vehicle is, for example, an agricultural tractor.

[0019] The cab suspension 12 in the agricultural tractor 10 comprises a load-bearing vehicle structure 14 and a driver's cab 16 that is spring-supported relative to the load-bearing vehicle structure 14. For the sake of clarity, only the basic frame 18 of the driver's cab 16 is shown, whereas the load-bearing vehicle structure 14 is formed by a gearbox housing 20 of a rear axle differential 22 and a front frame section 24.

[0020] How Fig. As can be seen from Figure 1, the cabin suspension 12 comprises right and left bearing blocks 28, 30 in the form of associated rubber bearings attached to a first cabin side 26 opposite the supporting vehicle structure 14, and right and left mechanical shock absorbers 34, 36 articulated to a second cabin side 32 opposite the supporting vehicle structure 14. The first cabin side 26 faces a front area and the second cabin side 32 faces a rear area of ​​the agricultural tractor 10.

[0021] The mechanical shock absorbers 34, 36 are of conventional design and comprise two segments mounted longitudinally displaceable into one another, which are supported against each other by an intermediate coil spring.

[0022] Each of the mechanical shock absorbers 34, 36 runs between a pivot point 38, 40 on the gearbox housing 20 of the rear axle differential 22 and a pivot point 42, 44 on the base frame 18 of the driver's cab 16. The pivot points 38, 40, 42, 44 are designed as pivot joints so that the mechanical shock absorbers 34, 36 can also follow lateral movements of the base frame 18. The movement of the base frame 18 is guided laterally relative to the supporting vehicle structure 14 by means of a control arm 46.

[0023] Furthermore, a mass 50, movable between the first and second cabin sides 26, 32 by means of a control device 48, is provided to change the neutral position of the mechanical shock absorbers 34, 36. The movable mass 50 is a mass body 52 arranged centrally on the base frame 18 between the pivot points 42, 44 of the mechanical shock absorbers 34, 36. This mass body 52 can be moved along a mechanical guide 56 in the area between the first and second cabin sides 26, 32 by means of an actuating element 54 encompassed by the control device 48. In this case, the mass body 52 is manufactured as a weight made of cast steel, which is mounted longitudinally in a guide rail 60 attached to the base frame 18 by means of a slide 58.An electric spindle drive 62, encompassed by the actuating element 54, allows the mass 52 to be moved steplessly back and forth along the guide rail 60 between a first and a second end stop. The mass 52 is located on the base frame 18 in the area of ​​a cabin floor 64, more precisely, below it.

[0024] The displacement of the mass body 52 is carried out by means of the electric spindle drive 62 at the instigation of a control unit 66 encompassed by the control device 48, such that the proportion of the total weight of the driver's cab 16 acting on the mechanical spring struts 34, 36 remains the same in the event of a change in the payload.

[0025] To determine the proportion of the total weight of the driver's cab 16 acting on the mechanical suspension struts 34, 36, the control unit 66 determines the extent of the payload based on a load-change-induced displacement of the suspension's neutral position occurring at the mechanical suspension struts 34, 36 and / or on the weight of a person at a vehicle seat (not shown). The vehicle seat, equipped with corresponding load-detection sensors 68, is a driver's seat or, if applicable, a passenger seat. The load-detection sensors 68 are either integrated into a corresponding seat surface of the vehicle seat in the form of strain gauges or detect the weight forces acting in the area of ​​a seat frame.The zero position of the mechanical shock absorbers 34, 36 is determined either statically, i.e., when the agricultural tractor 10 is stationary, or dynamically while driving. For this purpose, the control unit 66 performs a temporal integration or averaging of the deflections occurring at the mechanical shock absorbers 34, 36 around their respective zero positions. Position sensors 70, 72 are assigned to the mechanical shock absorbers 34, 36 to detect the respective compression state. The position information provided by the position sensors 70, 72 is then supplied to the control unit 66 for evaluation. Based on the displacement of the zero position determined from the position information, the control unit 66 then infers the load capacity, taking into account the spring stiffness of the mechanical shock absorbers 34, 36, which is assumed to be known.

[0026] From the load information thus obtained, the control unit 66 calculates a mass distribution achievable by varying the position of the movable mass body 52, which is suitable to compensate for the effect of the overall weight change in the area of ​​the pivot points 42, 44 of the mechanical shock absorbers 34, 36 on the base frame 18. The control unit 66 monitors compliance with the calculated position using the signals from an additional position sensor 74 associated with the electric spindle drive 62.

[0027] In this way, the proportion of the total weight of the driver's cab 16 acting on the mechanical shock absorbers 34, 36, and thus the neutral position of the mechanical shock absorbers 34, 36, can be influenced such that the available suspension travel during compression always remains the same, regardless of the load. Thus, if the mechanical shock absorbers 34, 36 are unloaded, for example, due to a driver change, the mass 52, and therefore the center of mass of the driver's cab 16, is shifted towards the mechanical shock absorbers 34, 36. Conversely, if the mechanical shock absorbers 34, 36 are loaded, for example, when a passenger gets in, the mass 52 is shifted towards the bearing blocks 28, 30 and thus away from the mechanical shock absorbers 34, 36. In both cases, the shift of the mass 52 is carried out in such a way that the neutral position of the suspension remains unchanged.The tuning of the suspension behavior of the mechanical struts 34, 36 of the cabin suspension 12 can therefore be carried out regardless of the respective payload situation in order to achieve optimal suspension comfort.

[0028] For example, the cabin suspension 12 is a component of an agricultural tractor 10. However, it can also be any other commercial vehicle, such as an agricultural vehicle of any type or a construction or forestry machine.

[0029] Fig. Figure 2 shows a second embodiment of the cabin suspension according to the invention. This differs from the first embodiment only in terms of the design of the displaceable mass.

[0030] Accordingly, the displaceable mass 50 is a liquid that can be moved back and forth between a first and a second ballast tank 78, 80 by means of an electrically driven pump 76 encompassed by the control unit 48, wherein the first ballast tank 78 is assigned to the first side of the cab 26 and the second ballast tank 80 to the second side of the cab 32. Depending on which of the two ballast tanks 78, 80 contains the larger quantity of liquid, the center of gravity shifts towards the first or the second side of the cab 26, 32. The liquid is hydraulic oil originating from the hydraulic system provided in the agricultural tractor 10.

[0031] The two ballast tanks 78, 80 communicate with each other via a connecting line 82, with the electrically driven pump 76 located within the connecting line 82. For clarity, the electrically driven pump 76 is shown in Fig. 2 shown lying outside the base frame 18, but in reality it is located spatially directly between the two ballast tanks 78, 80.

[0032] The electrically driven pump 76 is controlled by the control unit 66 in such a way that the proportion of the total weight of the driver's cab 16 acting on the mechanical suspension struts 34, 36 remains constant in the event of a change in the payload. The corresponding proportion of the total weight is also derived by the control unit 66 based on a load-change-induced displacement of the suspension neutral position occurring at the mechanical suspension struts 34, 36 and / or on the weight of a person at a vehicle seat (not shown). For further details regarding the procedure, please refer to the relevant explanations in connection with the [reference to be added]. Fig.Reference is made to the first embodiment shown in Figure 1. Taking into account the specific density of the hydraulic oil used, the control unit 66 calculates a quantity of fluid to be transferred or distributed between the two ballast tanks 78, 80, which is suitable to compensate for the effect of the overall weight change in the area of ​​the pivot points 42, 44 of the mechanical shock absorbers 34, 36 on the base frame 18. The control unit 66 monitors compliance with the quantity of fluid to be transferred or distributed by means of the signals from a flow rate sensor 84 arranged in the connecting line 82.

[0033] Accordingly, when the mechanical shock absorbers 34, 36 are unloaded, a corresponding quantity of fluid is pumped from the first ballast tank 78 to the second ballast tank 80, shifting the center of gravity of the driver's cab 16 towards the mechanical shock absorbers 34, 36. Conversely, when the mechanical shock absorbers 34, 36 are loaded, a corresponding quantity of fluid is pumped from the second ballast tank 80 to the first ballast tank 78 to shift the center of gravity of the driver's cab 16 towards the bearing blocks 28, 30, i.e., away from the mechanical shock absorbers 34, 36. In both cases, the fluid distribution between the two ballast tanks 78, 80 is adjusted such that the neutral position of the suspension at the mechanical shock absorbers 34, 36 remains unchanged.

Claims

[1] Cabin suspension for a commercial vehicle, comprising a load-bearing vehicle structure (14) and a driver's cab (16) which is spring-supported relative to the load-bearing vehicle structure (14), wherein bearing blocks (28, 30) are attached to a first side of the cab (26) relative to the load-bearing vehicle structure (14) and mechanical spring struts (34, 36) are articulated to a second side of the cab (32) relative to the load-bearing vehicle structure (14), characterized by , that furthermore a mass (50) which can be moved between the first and second cabin side (26, 32) by means of a control device (48) is provided to change a suspension zero position of the mechanical shock absorbers (34, 36). [2] Cabin suspension according to claim 1, characterized by, that the displacement of the mass (50) by means of the control device (48) is carried out in such a way that the proportion of the total weight of the driver's cabin (16) acting on the mechanical suspension struts (34, 36) remains the same in the event of a change in the payload. [3] Cabin suspension according to claim 1 or 2, characterized by , that the displaceable mass (50) is a mass body (52) which can be displaced along a mechanical guide (56) in the area between the first and second cabin sides (26, 32) by means of an actuating element (54) encompassed by the control device (48). [4] Cabin suspension according to claim 1 or 2, characterized by, that the displaceable mass (50) is a liquid which can be moved back and forth between a first and a second ballast tank (78, 80) by means of a pump (76) encompassed by the control device (48), wherein the first ballast tank (78) is spatially assigned to the first cabin side (26) and the second ballast tank (80) to the second cabin side (32). [5] Cabin suspension according to at least one of claims 1 to 4, characterized by , that the control device (48) determines the extent of the payload acting on the mechanical suspension struts (34, 36) according to a load-change-related displacement of the suspension neutral position occurring on the mechanical suspension struts (34, 36) and / or a person's weight detected at a vehicle seat. [6] Cabin suspension according to at least one of claims 1 to 5, characterized by, that the displaceable mass (50) is arranged centrally between the associated pivot points (42, 44) of the mechanical suspension struts (34, 36) on the driver's cab (16). [7] Cabin suspension according to at least one of claims 1 to 6, characterized by , that the displaceable mass (50) is arranged in the area of ​​a cabin floor (64), in particular lying underneath it. [8] Commercial vehicle, in particular agricultural tractor (10), with a cabin suspension (12) according to at least one of claims 1 to 7.

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