Method of controlling swing system of work machine

Abstract

A method of controlling a wobble system of a work machine is provided. The swing system includes a parking brake and a swing brake. The method includes outputting pilot pressure to the parking brake and the swing brake based on an operating mode of the swing system. When the pilot pressure is the first pilot pressure, the pilot pressure causes the parking brake to be applied to the wobble system and the drift brake not to be applied to the wobble system. When the pilot pressure is a second pilot pressure, the pilot pressure causes the parking brake not to be applied to the wobble system and the drift brake not to be applied to the wobble system, the second pilot pressure being greater than the first pilot pressure. When the pilot pressure is a third pilot pressure, the pilot pressure causes the parking brake not to be applied to the wobble system and the drift brake to be applied to the wobble system, the third pilot pressure being greater than the second pilot pressure.

Description

Technical Field

[0001] This invention relates to work vehicles. Specifically, this invention relates to a swing system for work vehicles. Background Technology

[0002] Work vehicles, such as excavators, may include a swing system configured to rotate the upper body (and any attached work tools) of the work vehicle relative to the lower body of the work vehicle.

[0003] Traditionally, the swaying system of a work vehicle can be driven by a hydraulic motor, which in turn can be actuated by hydraulic fluid supplied by a hydraulic fluid pump.

[0004] To prevent unintentional rotation of the oscillation system when the work vehicle is not in use, the oscillation system may be equipped with a parking brake. US-A-2022 / 282453 discloses a hydraulic system for engineering machinery, which includes a control valve inserted between a main pump and a hydraulic actuator; and a first electromagnetic proportional valve connected to a pilot port of the control valve. The hydraulic system also includes a brake for a rotary motor; and a second electromagnetic proportional valve connected via a secondary pressure line to a brake release port of the brake and via a primary pressure line to an auxiliary pump. A switching valve is inserted between the auxiliary pump and the first electromagnetic proportional valve, the switching valve including a pilot port connected to the secondary pressure line via a pilot line.

[0005] In this context, the present invention provides an improved, or at least commercially relevant, alternative oscillation system controller. Summary of the Invention

[0006] According to a first aspect, a method for controlling a swing system of a working machine is provided. The swing system includes a parking brake and a drift brake. The method includes outputting a pilot pressure to the parking brake and the drift brake based on an operating mode of the swing system. When the pilot pressure is a first pilot pressure, the pilot pressure causes the parking brake to be applied to the swing system and the drift brake not to be applied to the swing system. When the pilot pressure is a second pilot pressure, the pilot pressure causes the parking brake not to be applied to the swing system and the drift brake not to be applied to the swing system, wherein the second pilot pressure is greater than the first pilot pressure. When the pilot pressure is a third pilot pressure, the pilot pressure causes the parking brake not to be applied to the swing system and the drift brake to be applied to the swing system, wherein the third pilot pressure is greater than the second pilot pressure.

[0007] According to the first aspect, pilot pressure is used to actuate both the parking brake and drift brake of the oscillating system. Accordingly, the method of the first aspect provides control of the parking brake and drift brake of the oscillating system via a shared pilot pressure.

[0008] Furthermore, according to the method of the first aspect, the parking brake is applied under a first pilot pressure, which is lower than the second and third pilot pressures when the parking brake is not applied. In practice, the parking brake is a negative brake (i.e., typically on the brake), such that the parking brake can be applied to the sway system when it is not in operation (e.g., in parking mode). Operation of the sway system, resulting in an increase in pilot pressure, can allow the drift brake and parking brake not to be applied to the sway system (e.g., allowing the sway system to rotate, or applying the drift brake). Accordingly, the drift brake can be a positive brake, adapted to counteract the rotation of the sway system during operation of the working vehicle.

[0009] According to a second aspect of the present invention, a swing system controller for a swing system of a working machine is provided. The swing system controller is configured to:

[0010] Obtain the operating mode of the swing system;

[0011] The pilot pressure output to the parking brake and drift brake of the oscillation system is controlled based on the operating mode, wherein the oscillation system controller is configured to cause the oscillation system to operate in the following manner:

[0012] In a first configuration, a first pilot pressure causes the parking brake to be applied to the sway system and the drift brake to be unapplied to the sway system.

[0013] In a second configuration, a second pilot pressure causes the parking brake not to be applied to the sway system and the drift brake not to be applied to the sway system, wherein the second pilot pressure is greater than the first pilot pressure; and

[0014] In a third configuration, a third pilot pressure causes the parking brake not to be applied to the sway system and the drift brake to be applied to the sway system, wherein the third pilot pressure is greater than the second pilot pressure.

[0015] Accordingly, the swing system controller of the second aspect can be configured to cause the swing system of the working machine to perform the method of the first aspect.

[0016] According to a third aspect of the invention, a swaying system for a work vehicle is provided. The swaying system is configured to cause the upper body of the work vehicle to rotate relative to the lower body of the work vehicle. The swaying system includes a parking brake and a drift brake, the parking brake being configured to apply a parking braking torque based on a pilot pressure to counteract the rotation of the swaying system, and the drift brake being configured to apply a drift braking torque based on the pilot pressure to counteract the rotation of the swaying system. The swaying system also includes a swaying system controller according to the second aspect.

[0017] Accordingly, the swing system of the third aspect can be used to perform the method according to the first aspect of the invention. Attached Figure Description

[0018] Embodiments of the invention will now be discussed with reference to the following non-limiting drawings, in which:

[0019] - Figure 1 This is a diagram of an open-loop hydraulic system used in a swing system;

[0020] - Figure 2 This is a diagram of a closed-loop hydraulic system used in a swing system;

[0021] - Figure 3a , Figure 3b and Figure 3c Cross-sectional views of the swing brake according to the present invention in different configurations;

[0022] - Figure 4a and Figure 4b It is a graph showing the changes in pilot pressure and braking torque when the sway braking system is operated; and

[0023] - Figure 5 A diagram of a hydraulic system according to the present invention is shown. Detailed Implementation

[0024] According to an embodiment of the present invention, a work vehicle 1 including a swing system 3 is provided. The work vehicle also includes a swing system controller configured to control the swing system 3. According to an embodiment of the present invention, the swing system includes a swing brake 10 configured to counteract or prevent rotation of the swing system 3.

[0025] According to the present invention, the work vehicle 1 may be an excavator (not shown). The work vehicle 1 may include an upper body and a lower body. The swing system 3 (not shown) of the work vehicle 1 may be configured to rotate the upper body (and any attached work tools) of the work vehicle 1 relative to the lower body of the work vehicle 1. The design of the swing system 3 for the work vehicle 1 (e.g., an excavator, etc.) is known to those skilled in the art.

[0026] The oscillation system 3 may include an oscillation motor 4. The oscillation motor 4 may be configured to cause the upper body of the work vehicle 1 to rotate relative to the lower body of the work vehicle 1. In some embodiments, the oscillation motor 4 may be driven by a hydraulic system, which may be an open-loop hydraulic system or a closed-loop hydraulic system.

[0027] Figure 1 A diagram of the open-loop hydraulic system for the oscillating system 3 is shown. The open-loop hydraulic system includes a hydraulic motor 4, a directional control valve 5, a hydraulic pump 6, a hydraulic reservoir 7, a motor 8, and a pressure relief valve 9.

[0028] Hydraulic pump 6 is configured to pump hydraulic fluid to the oscillating motor, causing the oscillating motor to rotate. Figure 1 In the open-loop hydraulic system, the directional control valve 5 can be controlled to allow hydraulic fluid to flow to the hydraulic motor 4. The flow of hydraulic fluid to the hydraulic motor 4 causes the hydraulic motor 4 to drive the oscillating system 3, thereby changing the rotational position of the oscillating system 3. Figure 1 The directional control valve 5 is a 4 / 3-way directional control valve. When it is necessary to maintain the rotational position of the oscillating system, the directional control valve 5 can be moved to a central position where hydraulic fluid flow is not permitted. Thus, during the use of the work vehicle, the operation of the directional control valve 5 to the central position can provide at least some resistance to the unintentional rotation of the oscillating system 3.

[0029] like Figure 1 As shown, the open-loop hydraulic system includes a hydraulic reservoir 7 for storing hydraulic fluid. Hydraulic fluid can be supplied from the hydraulic reservoir 7 to the hydraulic pump 6. Figure 1 As shown, hydraulic fluid can be returned to the hydraulic reservoir 7 via the directional control valve 5 or via the pressure relief valve 9. Figure 1 In the system, the hydraulic pump 6 can be configured to pump a continuous flow of hydraulic fluid, wherein the hydraulic fluid flows either through the directional control valve when open, or through the pressure relief valve 9 when the directional control valve 5 is in the (center) closed position. Thus, during operation, the hydraulic fluid can continuously flow back to the hydraulic reservoir 7.

[0030] Figure 2 A diagram of a closed-loop hydraulic system for the oscillating system 3 is shown. The closed-loop hydraulic system includes a hydraulic motor 4a and a hydraulic pump 6a. Typically, the closed-loop hydraulic system is configured to circulate hydraulic fluid between the hydraulic pump 6a and the hydraulic motor 4a. Thus, Figure 2 The hydraulic pump 6a can be a bidirectional hydraulic pump configured to directly drive the hydraulic motor 4a. Using the bidirectional hydraulic pump 6a in a closed-loop hydraulic system allows the hydraulic motor 4a to be controlled solely by the pump flow rate (i.e., without the need for a directional control valve in an open-loop system). Therefore, in Figure 2In a closed-loop system, hydraulic fluid can flow through the system only when it is desired to rotate the oscillating system 3. When rotation of the oscillating system 3 is not desired, hydraulic pressure output by the hydraulic pump 6a can be used to maintain the rotational position of the oscillating motor 4a. It should be understood that a closed-loop hydraulic system may be more prone to unintentional rotation of the oscillating system. In particular, during the use of a closed-loop hydraulic system, internal hydraulic fluid leakage in the closed-loop circuit may cause unintentional drift / slippage of the oscillating motor 4a / oscillating system 3. To reduce or prevent unintentional drift / slippage of the oscillating system 3 during use, the oscillating system 3 can be controlled according to embodiments of the present invention.

[0031] The sway system 3 includes a sway brake 10. The sway brake 10 can be configured to counteract or prevent rotation of the sway system 3 (i.e., rotation of the upper body of the work vehicle 1 relative to the lower body of the work vehicle 1). The sway brake 10 includes a parking brake 20 and a drift brake 30.

[0032] like Figure 3a As shown, the swing brake 10 can be arranged about its central axis 12. This swing brake can be configured to apply torque to the drive shaft 16 of the swing system 3. The drive shaft 16 can be connected to hydraulic motors 4, 4a. Rotation of the drive shaft 16 can cause the upper body of the work vehicle 1 to rotate relative to the lower body of the work vehicle 1 (not necessarily about the central axis 12 of the drive shaft 16). The swing brake 10 may include a swing brake housing 14. The swing brake housing 14 can be connected to either the lower body or the upper body of the work vehicle 1. Figure 3a In one embodiment, the swing brake housing is connected to the upper body of the work vehicle 1. A drive shaft 16 extending through the swing brake 10 can be connected to a swing drive unit including a reduction gear set. Figure 3a (Not shown in the image).

[0033] Although Figure 3a In one embodiment, the parking brake 20 and the drift brake 30 are integrated together as the swing brake 10, but in other embodiments, the parking brake 20 and the drift brake 30 may be provided as separate brakes for the swing system 3.

[0034] The parking brake 20 can be configured to apply parking braking torque to counteract the rotation of the oscillating system 3.

[0035] Figure 3a A schematic cross-sectional view of a parking brake 20 according to an embodiment of the present invention is shown. The parking brake 20 includes at least one parking brake disc 22, at least one parking friction disc 24, a first spring element 26, and a parking piston 28. Figure 3aAs shown, the first spring element 26 is configured to bias the parking friction disc 24 toward the parking brake disc 22. In the absence of any external force, the first spring element 26 is configured to elastically bias the parking friction disc 24 toward the parking brake disc 22, such that the parking friction disc 24 and the parking brake disc 22 are in contact with each other. The force applied by the first spring element 26 causes a parking brake torque to be applied between the parking brake friction disc 24 and the parking brake disc 22. Accordingly, the parking brake 20 is a negative brake, which applies the parking brake torque to the oscillating system 3 to prevent or counteract rotation of the oscillating system 3 in the absence of any force applied from the parking brake piston 28.

[0036] The at least one parking brake disc 22 may be generally annular. Each parking brake disc 22 may be arranged around the central axis 12, such as... Figure 3a As shown in the diagram. Each parking brake disc 22 may have a first coefficient of friction. The parking brake disc 22 may be connected to a first swing brake body or a second swing brake body. Figures 3a-3c In this embodiment, a plurality of parking brake discs 22 are provided. The plurality of parking brake discs 22 are arranged alternately with at least one parking brake friction disc 24 along the central axis 12 of the drive shaft 16. Figure 3a In this embodiment, each parking brake disc 22 is configured to engage with the swing brake housing 14. That is, each parking brake disc 22 is fixed to the swing brake housing 14, while the drive shaft 16 is free to rotate relative to the swing brake housing 14.

[0037] The at least one parking friction disc 24 can be configured to contact the at least one parking brake disc 22 when the parking brake 20 is engaged. Each parking friction disc 24 can have a first friction disc coefficient. Figure 3a As shown, each parking friction disc 24 can also be annular. In Figures 3a-3c In this embodiment, a plurality of parking friction discs 24 are provided. The plurality of parking friction discs 24 may be arranged alternately with at least one parking brake disc 22. Figure 3a In one embodiment, each parking friction disc 24 can be configured to engage with the drive shaft 16. Accordingly, each parking friction disc 24 can be configured to rotate together with the drive shaft 16 (i.e., at the same rotational speed as the drive shaft 16). That is, when the drive shaft 16 of the oscillating system 3 rotates, each parking friction disc 24 can rotate relative to the at least one parking brake disc 22.

[0038] Multiple spring elements 26 may be arranged around the parking friction disc 24 to apply parking brake torque uniformly around the central axis 12. Accordingly, the one or more spring elements 26 may be configured to apply force to the parking brake piston 28 to bias the parking brake disc 22 and the parking friction disc 24 together to counteract rotation of the drive shaft 16.

[0039] Parking brake piston 28 Figure 3a It is illustrated schematically. For example... Figure 3a As shown, the parking brake piston 28 is disposed within the parking brake cylinder volume 29. The parking brake cylinder volume 29 may be at least partially defined by the swing brake housing 14, as... Figure 3a As shown. In other embodiments, the parking brake cylinder volume 29 may be defined by a parking brake cylinder (not shown), in which a parking brake piston 28 is arranged. Accordingly, in some embodiments, the parking brake 20 includes a parking brake hydraulic actuator, wherein the parking brake hydraulic actuator is configured to apply a force against a force applied by a first spring element 26.

[0040] The parking brake cylinder volume 29 can be configured to receive hydraulic fluid flow from the hydraulic system. For example, from... Figure 3b As understood, when hydraulic fluid is pumped into the parking brake cylinder volume, the hydraulic fluid pressure generates a force opposite to the spring force applied by the first spring element 26. Accordingly, under sufficient hydraulic pressure, the parking brake piston 28 can be displaced within the parking brake cylinder volume 29, causing the parking friction disc 24 to separate from the parking brake disc 22.

[0041] Understandably, the first spring element 26 applies a force to the parking brake piston 28, which pushes the parking friction disc 24 against the parking brake disc 22. Accordingly, when the hydraulic fluid pressure supplied to the parking brake cylinder 29 decreases, the first spring element 26 can act to return the piston 28 to its original position. Figure 3a The position shown is where hydraulic fluid is expelled from parking brake cylinder 29. Figure 3a In this embodiment, the first spring element 26 is depicted as a helical spring. It will be understood that any suitable spring element can be used to elastically bias the parking friction disc 24 toward the parking brake disc 22.

[0042] The drift brake 30 can be configured to apply drift braking torque to counteract the rotation of the oscillating system 3. For example... Figure 3a As shown, the drift brake 30 is a positive brake including a second spring element 32 configured to counteract the application of drift braking torque. The drift brake 30 includes at least one drift brake disc 32, at least one drift friction disc 34, a second spring element 36, and a drift piston 38. Figure 3aAs shown, the second spring element 36 is configured to bias the drift friction disc 34 away from the drift brake disc 32. Therefore, without any external force, the second spring element 36 is configured to separate the drift friction disc 34 from the drift brake disc 32. The force applied by the second spring element 36 can be significantly lower than the force applied by the first spring element 26. Accordingly, the drift brake 30 is a positive brake, wherein the second spring element counteracts the application of the drift braking torque.

[0043] Similar to the parking brake 20, each brake disc 32 can be generally annular. The drift brake discs 32 can be arranged around the central axis 12, such as... Figure 3a As shown. Each drift brake disc 32 may have a second coefficient of friction. In some embodiments, the first coefficient of friction of each parking brake disc 22 is different from the second coefficient of friction of the drift brake disc 32. Therefore, the performance characteristics of the parking brake 20 and the drift brake 30 can be selected to meet different purposes. For example, in some embodiments, the second coefficient of friction may be lower than the first coefficient of friction. In this way, the parking brake disc 22 can be provided with a relatively high first coefficient of friction to provide a relatively high and reliable application of parking braking torque. One possible result of selecting a relatively high coefficient of friction for the disc brake is that the wear rate of the disc brake can be increased. For the parking brake 20, which is intended to be applied only when the vehicle is stationary, the expected wear rate of the parking disc brake can be relatively low. The drift brake disc 32 may be provided with a relatively low second coefficient of friction to reflect the intention to apply the drift brake disc 32 when the work vehicle 1 is operable. In this usage situation, unintentional slippage of the swing brake may occur. Therefore, the second coefficient of friction of the drift brake disc 32 can be selected to improve the life of the drift brake disc 32 (relative to a disc brake with the same first coefficient of friction).

[0044] exist Figure 3a In one embodiment, each drift brake disc 32 can be configured to engage with the swing brake housing 14. That is, each drift brake disc 32 can be fixed to the swing brake housing 14, while the drive shaft 16 can rotate freely relative to the swing brake housing 14, so that the drift brake disc 32 can be connected to the swing brake body of the same swing brake 10 as the parking brake disc 22.

[0045] Drift friction discs 34 can be configured to contact drift brake discs 32 when the drift brake is engaged. These drift friction discs 34 can have a second friction coefficient. The first friction coefficient can be lower than the second friction coefficient, similar to the friction coefficients of brake discs 22 and 32 discussed above. Figures 3a-3c In this embodiment, a plurality of drift friction discs 34 are provided. These plurality of drift friction discs 34 can be arranged alternately with the at least one drift brake disc 32. Figure 3a In this embodiment, each drift friction disc 34 can be configured to engage with the drive shaft 16. Accordingly, each drift friction disc 34 can be configured to rotate together with the drive shaft 16. That is, when the oscillation system 3 rotates, each drift friction disc 34 can rotate relative to the at least one drift brake disc 32.

[0046] like Figure 3a As shown, the drift brake piston 38 can be configured to apply force to bias the drift brake disc 32 and the drift friction disc 34 together in order to counteract the rotation of the drive shaft 16.

[0047] Multiple second spring elements 36 may be arranged around the drift friction disc 34 to apply drift braking torque uniformly around the drive shaft 16. In some embodiments, the force applied by one or more second spring elements 36 may be greater than the force applied by the first spring element 26.

[0048] exist Figure 3a The drift brake piston 38 is schematically shown in the diagram. (As shown) Figure 3a As shown, the drift brake piston 38 can be disposed within the drift brake cylinder volume 39. The drift brake cylinder volume 39 can be at least partially defined by the swing brake housing 14, as... Figure 3a As shown. In other embodiments, the drift brake cylinder volume 39 may be defined by a drift brake cylinder (not shown) in which a drift brake piston 38 is arranged. The drift brake cylinder volume 39 may be configured to receive a flow of hydraulic fluid from a hydraulic system. Accordingly, in some embodiments, the drift brake 30 may include a drift brake hydraulic actuator configured to apply a force against a force applied by a second spring element 36.

[0049] If from Figure 3c Understandably, when hydraulic fluid is pumped into the drift brake cylinder volume 39, the hydraulic fluid pressure generates a force opposite to the spring force applied by the second spring element 36. Accordingly, under sufficient hydraulic pressure, the drift brake piston 38 can drift within the drift brake cylinder volume 39, causing the drift friction disc 34 to contact and applying torque to the drift brake disc 32. The torque applied to the drift brake disc 32 can be proportional to the force applied to the drift brake piston 38 from the hydraulic fluid pressure.

[0050] Understandably, the second spring element 36 applies a force to the drift brake piston 38, which elastically biases the drift friction disc 34 and the drift brake disc 32 away from each other. Accordingly, when the hydraulic fluid pressure supplied to the drift brake cylinder 39 decreases, the second spring element 36 can act to return the drift brake piston 38 to its original position. Figure 3a The position shown indicates that hydraulic fluid is driven out of drift brake cylinder 39. Figure 3a In this embodiment, the second spring element 36 is depicted as a helical spring. It will be understood that any suitable spring element can be used to elastically bias the drift friction disc 34 and the drift brake disc 32 together.

[0051] Figure 3a , Figure 3b and Figure 3c A swing brake 10 is shown, wherein a parking brake 20 and a drift brake 30 are arranged concentrically about a central axis 12. Figure 3a In one embodiment, the parking brake 20 and the drift brake 30 each extend in a plane transverse to the central axis 12. Figure 3a In some embodiments, the parking brake 20 and the drift brake 30 extend in planes that are perpendicularly offset from each other. In some embodiments, such as... Figure 3a As shown, the parking brake 20 and drift brake 30 may each have an inner diameter, which may be defined by the inner diameters of the parking brake disc 22 and drift brake disc 32, respectively. Figure 3a In one embodiment, the parking brake 20 and drift brake 30 have approximately the same inner diameter. In other embodiments, the inner diameters may be different. In other embodiments, the parking brake 20 and drift brake 30 may extend in the same plane, wherein the parking brake 20 and drift brake have different inner diameters. Therefore, it should be understood that the swing brake 10 of the present invention is not limited to... Figure 3a The arrangement of the parking brake 20 and drift brake 30 shown.

[0052] If from Figure 3a , Figure 3b and Figure 3c As understood, the swing brake 10 can be configured in one of three configurations. In such a configuration... Figure 3a In the first configuration shown, the parking brake 20 is configured to apply parking braking torque to the sway system 3, and the drift brake 30 is configured not to apply torque to the sway system 3. Accordingly, the first configuration is suitable for operating the work vehicle 1 in parking mode (i.e., the work vehicle 1 is parked). Since the parking brake 20 is a negative brake, it can be applied without the need for operation of the hydraulic pumps 6, 6a.

[0053] In such Figure 3b In the second configuration shown, the parking brake 20 can be configured to apply no torque, and the drift brake 30 can be configured to apply no torque. Accordingly, in the second configuration, the swing brake 10 can be configured not to counteract the rotation of the swing system 3. Therefore, in the second configuration, the swing system 3 can cause the hydraulic motors 4, 4a to rotate the upper vehicle body relative to the lower vehicle body. That is, the swing brake 10 can be in the second configuration when it is desired that the swing system 3 rotate.

[0054] In such Figure 3c In the third configuration shown, the parking brake 20 can be configured not to apply torque, and the drift brake 30 can be configured to apply drift braking torque. Therefore, in this third configuration, the drift brake 30 can be engaged to prevent or counteract rotation of the sway system 3. As mentioned above, the drift torque applied by the drift brake 30 is lower than the parking brake torque. This third configuration of the sway brake 10 can be utilized when the work vehicle is in operation and it is desired that the sway system 3 not rotate (e.g., when the work vehicle 1 is performing digging or driving operations). During such operation, it may not be desirable to apply a higher parking brake torque, as such a relatively high torque could result in excessive stress / strain on the sway system 3 / work vehicle 1. Therefore, the drift brake 30 can be used to apply a lower drift braking torque to reduce and / or prevent damage to the sway system 3 / work vehicle 1. Since the drift brake 30 is to be engaged when the work vehicle 1 is in operation, the drift brake is a positive brake. Furthermore, the design of the swing brake 30 can be optimized for improved wear relative to the parking brake 20 (e.g., optimization of the drift brake disc 22) to reflect different uses of the drift brake 30.

[0055] As described above, the parking brake 20 and drift brake 30 can each be operated by hydraulic fluid flowing into and out of the parking brake cylinder volume 29 and drift brake cylinder volume 39, respectively. Accordingly, in some embodiments, the work vehicle 1 may include a swing brake hydraulic system configured to control / operate the swing brake 10. The swing brake hydraulic system may include a swing brake pump configured to pump hydraulic fluid from a hydraulic fluid reservoir (e.g., hydraulic reservoir 7) to the parking brake 20 and drift brake 30.

[0056] The swing brake hydraulic system can be configured to output a variable pilot pressure to control the parking brake 20 and the drift brake 30. Thus, the swing brake hydraulic system can be a pilot pressure system through which the swing brake 10 is operated.

[0057] As described above, the oscillation system 3 may include an oscillation system controller ( Figure 3a (Not shown in the image), the sway system controller is configured to control the sway brake 10. The sway system controller can be any suitable processor or computer. In some embodiments, the sway system 3 may include a dedicated processor (i.e., separate from the controller of the work vehicle 1). In other embodiments, the functionality of the sway system controller may be integrated into another controller of the work vehicle, such as an engine control unit (ECU).

[0058] Next, we will see Figure 4a , Figure 4b and Figure 5 Describe a method of controlling a swing system 3. The method includes outputting a pilot pressure to a parking brake 20 and a drift brake 30 based on an operation mode of the swing system 3. In some embodiments, a swing system controller may determine the operation mode of the swing system 3 and accordingly select the pilot pressure to be output to the parking brake 20 and the drift brake 30.

[0059] In some embodiments, a swing braking hydraulic system may include a hydraulic pump 40 and a proportional valve 50. The proportional valve 50 may be configured to output a variable pilot pressure. In some embodiments, the proportional valve 50 may include a solenoid, where the current received by the solenoid (under the control of the swing system controller) controls the variable opening of the proportional valve 50. A hydraulic system diagram showing the proportional valve 50 is shown in Figure 5 is shown in.

[0060] In one embodiment, the hydraulic pump 40 may be configured to pump hydraulic fluid to the proportional valve 50. The proportional valve 50 may be a 3 / 2-way proportional valve. The proportional valve 50 may be configured to supply hydraulic fluid to the parking brake 20 and the drift brake 30 under a pilot pressure controlled by the proportional valve 50. The proportional valve 50 may also be connected to a hydraulic reservoir 7 to provide a return path for the hydraulic fluid.

[0061] By way of explanation, Figure 4a shows a graph representing the pilot pressure output from the proportional valve 50 in response to the current supplied to the solenoid of the proportional valve 50. As Figure 4a shown, below the minimum current, the pilot pressure output by the proportional valve 50 is substantially zero (i.e., the proportional valve 50 is closed and no hydraulic fluid flows through the valve). When the current supplied to the solenoid increases, the proportional valve 50 begins to open, and the pilot pressure of the hydraulic fluid increases accordingly. In Figure 4a the embodiment, the relationship between the solenoid current and the pilot pressure is represented as being substantially linear. In other embodiments, other current / pressure relationships may be provided. Above a certain solenoid current, the proportional valve is fully open, and the pilot pressure reaches the maximum pilot pressure.

[0062] Figure 4b shows a graph of the braking torque applied by the swing brake 10 when both the parking brake 20 and the drift brake 30 are controlled by the pilot pressure from the proportional valve 50.

[0063] As Figure 4b shown, when the pilot pressure (p) is the first pilot pressure (e.g., p o ≤ p < p1, as Figure 4bAs shown, the pilot pressure causes the parking brake 20 to act on the swing system 3, while causing the drift brake 30 not to act on the swing system 3. Thus, as Figure 4a and Figure 4b shown, when no solenoid current is supplied, the pilot pressure is substantially zero. Therefore, the hydraulic pressure supplied to the swing brake 10 is not sufficient to overcome the force exerted on the parking brake 20 by the first spring element 26, such that the parking brake 20 (negative brake) is applied to the swing system 3. There is also not enough hydraulic pressure to overcome the force exerted on the drift brake 30 by the second spring element 36, such that the drift brake 30 is not applied to the swing system 3. Thus, as Figure 4b shown, the swing brake 10 is in the first configuration (1 st Config).

[0064] In some embodiments, the parking brake 20 can be a negative brake such that, when the parking brake 20 is applied to the swing system 3, the parking brake 20 applies a predetermined parking brake torque to the swing system 3. In Figure 3a the embodiments, the first spring element 26 can be configured to elastically bias the parking brake to apply a predetermined parking brake torque.

[0065] When the pilot pressure (p) is a second pilot pressure (e.g., p2 ≤ p < p3), the pilot pressure causes the parking brake 20 not to be applied to the swing system 3 and causes the drift brake 30 not to be applied to the swing system 3, the second pilot pressure being greater than the first pilot pressure.

[0066] That is, the second pilot pressure is sufficient to cause the parking brake 20 not to be applied at all. However, the second pilot pressure is not sufficient to overcome the force exerted by the second spring element 36, such that the drift brake 30 is not applied. Therefore, the swing brake 10 can operate in a second configuration (2 nd Config) in which neither the parking brake 20 nor the drift brake 30 is applied and the swing system 3 can rotate.

[0067] When the pilot pressure is a third pilot pressure (e.g., p3 ≤ p), the pilot pressure causes the parking brake 20 not to be applied to the swing system 3 and causes the drift brake 30 to be applied to the swing system 3, the third pilot pressure being greater than the second pilot pressure. Thus, at the third pilot pressure, the parking brake 20 remains not applied. The third pilot pressure causes the pilot pressure to overcome the force exerted by the second spring element 36, such that the drift brake 30 is applied at this time. As Figure 4b shown, when the pilot pressure increases above p3, the torque applied by the drift brake 30 can increase.

[0068] In some embodiments, when the drift brake 30 is applied to the swing system 3, the drift brake 30 applies a drift braking torque to the swing system 3, where the drift braking torque is lower than the parking braking torque.

[0069] It will be noted that between the pressures p1 and p2 shown, the pilot pressure is sufficient to partially lift (but not completely disengage) the parking brake 20. To avoid unnecessary wear of the parking brake 20, it may be undesirable to operate the swing brake 10 in this pilot pressure region where the parking brake 20 is partially applied (between the Figure 4b first configuration and the second configuration of Figure 4b ).

[0070] In some embodiments, when the pilot pressure is between a third pilot pressure and a fourth pilot pressure (p3 ≤ p ≤ p4), where the fourth pilot pressure is greater than the third pilot pressure, the drift braking torque applied to the swing system 3 can vary between a minimum drift braking torque (T0) and a maximum drift braking torque (T1) based on the pilot pressure (p). Accordingly, in some embodiments, the swing system controller can use the pilot pressure to control the drift braking torque to be applied to the swing system 3.

[0071] Accordingly, in some embodiments, a pilot pressure system can be used to control the parking brake 20 and the drift brake 30 of the swing brake 10 using a single proportional valve 50. Such an implementation allows for the control of the swing brake 10 in a simplified manner using a single proportional valve 50 as Figure 5 shown. Since the pilot pressure causes the parking brake 20 to be applied in a pressure range (p ≤ p < p1) different from the pressure range (p3 ≤ p) in which the drift brake is applied, the control method of the present invention ensures that the parking brake 20 and the drift brake 30 cannot be applied simultaneously. This in turn ensures that the swing system 3 is not placed in a configuration where it may be subjected to excessive braking torque (combined parking braking torque and drift braking torque). o

[0072] In some embodiments, the swing system controller can be configured to control the parking brake 20 and the drift brake 30 based on the operating mode of the work vehicle 1. Accordingly, in some embodiments, the method can further include the step of: the swing system controller obtaining information indicative of the operating mode of the work vehicle.

[0073] In some embodiments, the swing system controller may obtain information indicating that the work vehicle 1 is in a parking operation mode. When the work vehicle is in the parking operation mode, the method further includes causing the pilot pressure system to output a first pilot pressure, such that the system is in a first configuration. Furthermore, when the work vehicle 1 is not in operation, the swing brake 10 may also default to the first configuration due to the negative parking brake 20 and the positive drift brake 30.

[0074] When the sway system controller receives information indicating that the work vehicle 1 is in a sway operation mode, the method further includes causing the pilot pressure system to output a second pilot pressure. The sway operation mode can be an operation mode in which the sway system controller determines that rotation of the sway system 3 is desired. In the sway system, the sway brake can be in a second configuration to allow rotation of the sway system 3.

[0075] When information is received indicating that the work vehicle is in excavation or driving operation mode, the method also includes outputting pilot pressures of at least a third pilot pressure and up to a fourth pilot pressure. In such an operation mode, it may be desirable to apply drift brake 30.

[0076] like Figure 4b As shown, when the swing brake 10 operates in the third configuration, the swing system controller can utilize a pilot pressure system to control the drift braking torque applied by the swing brake 10. Accordingly, in some embodiments, the swing system controller can control the applied drift braking torque based on the operating mode of the work vehicle 1. For example, in some embodiments, it may be desirable to change the applied drift braking torque based on the position information of the work vehicle. That is, when the work vehicle is operating, for example, on a slope, it may be desirable to increase the drift braking torque. Therefore, in some embodiments, the method may further include the swing system controller obtaining position information indicating the position of the swing system 3 and / or the position of the work vehicle 1. The drift braking torque applied by the drift brake 30 can then be controlled based on the obtained position information.

[0077] In some embodiments, the position information of the oscillation system 3 may be derived by the oscillation system controller from one or more position information sensors of the work vehicle 1 (e.g., one or more gyroscopes, accelerometers, etc. connected to the work vehicle). In some embodiments, the position information of the work vehicle 1 may be provided by the ECU of the work vehicle 1. In some embodiments, the position information may include one or more of the yaw, pitch, and roll of the oscillation system 3. The oscillation system controller may determine the drift braking torque to be applied by the oscillation brake 10 based on the position information.

[0078] For example, when the oscillation system 3 is operating on a substantially level ground, the oscillation system controller can determine that a first drift braking torque will be applied by the oscillation brake 10. If at least one of the pitch, yaw, and roll of the oscillation system 3 is determined to be above a first threshold, the oscillation system controller can determine that a second drift braking torque will be applied by the oscillation brake 10, wherein the second drift braking torque is higher than the first drift braking torque. In other embodiments, a linear relationship between one or more of the pitch, yaw, and roll of the oscillation system 3 and the drift braking torque can be used.

[0079] Of course, in some embodiments, when the work vehicle 1 is in operation, the swing system controller can determine, based on user input, that the swing brake 10 should be in one of the first, second, or third configurations. That is, the configuration of the swing brake 10 can also be manually controlled by the user.

[0080] Industrial applicability

[0081] According to the present invention, a method for controlling the oscillation system 3 of a working machine 1 is provided. According to this method, a pilot pressure is used to actuate both the parking brake 20 and the drift brake 30 of the oscillation system 3. Accordingly, the present invention provides control of the parking brake 20 and the drift brake 30 of the oscillation system via a common pilot pressure.

[0082] Furthermore, according to this method, the parking brake 20 is applied under a first pilot pressure, which is lower than the second and third pilot pressures when the parking brake 20 is not applied. In practice, the parking brake 20 can be a negative brake (i.e., typically on the brake), such that the parking brake 20 can be applied to the sway system 3 when the sway system 3 is not operating (e.g., in parking mode). Operation of the sway system 3, resulting in an increase in pilot pressure, can allow the drift brake 30 and the parking brake 20 not to be applied to the sway system 3 (e.g., allowing the sway system to rotate, or applying the drift brake). Accordingly, the drift brake 30 can be a positive brake, adapted to counteract the rotation of the sway system 3 during operation of the work vehicle 1.

[0083] In some embodiments, the work vehicle 1 may be an excavator. Accordingly, the method of the present invention may be particularly advantageous for controlling the rotation of the upper body of the excavator relative to the lower body of the excavator.

[0084] In some embodiments, the sway system 3 of the work vehicle may be driven by a hydraulic motor 4a, which is provided as part of a closed-loop hydraulic system. For such a hydraulic system, the method of the present invention can be used to reduce or prevent unintentional slippage / rotation of the sway system 3 during use of the work vehicle 1 without the need for applying the parking brake 20. The application of the parking brake 20 during use of the work vehicle 1 may lead to overloading of the sway system 3 and / or excessive wear of the parking brake 20 due to the relatively large parking braking torque associated with it.

Claims

1. A method for controlling a swing system of a working machine, the swing system comprising a parking brake and a drift brake, the method comprising: Based on the operating mode of the aforementioned oscillation system, pilot pressure is output to the parking brake and the drift brake, wherein: When the pilot pressure is a first pilot pressure, the pilot pressure causes the parking brake to be applied to the oscillation system and the drift brake not to be applied to the oscillation system; When the pilot pressure is the second pilot pressure, the pilot pressure causes the parking brake not to be applied to the sway system and the drift brake not to be applied to the sway system, wherein the second pilot pressure is greater than the first pilot pressure; and When the pilot pressure is the third pilot pressure, the pilot pressure causes the parking brake not to be applied to the oscillation system and the drift brake to be applied to the oscillation system, and the third pilot pressure is greater than the second pilot pressure.

2. The method according to claim 1, wherein When the parking brake is applied to the oscillating system, the parking brake applies a predetermined parking braking torque to the oscillating system.

3. The method according to claim 2, wherein The parking brake includes a first spring element, wherein the first spring element biases the parking brake to apply the parking braking torque to the oscillating system.

4. The method according to claim 2 or 3, wherein When the drift brake is applied to the oscillating system, the drift brake applies a drift braking torque to the oscillating system, which is lower than the parking brake torque.

5. The method according to claim 4, wherein When the pilot pressure is between the third pilot pressure and the fourth pilot pressure, the fourth pilot pressure is greater than the third pilot pressure, and the drift braking torque applied to the oscillating braking system can vary between the minimum drift braking torque and the maximum drift braking torque based on the pilot pressure.

6. The method according to any one of claims 1 to 5, wherein The pilot pressure output to the drift brake and the parking brake is controlled by a proportional hydraulic valve.

7. The method according to any one of claims 1 to 6, further comprising: Obtain information indicating the operating mode of the work vehicle; and The pilot pressure output to the drift brake and the parking brake is controlled based on the operating mode of the work vehicle.

8. The method according to claim 7, wherein Upon receiving information indicating that the work vehicle is in parking operation mode, the method includes: Output the first pilot pressure; and / or When information is received indicating that the work vehicle is in a swing operation mode, the method includes outputting the second pilot pressure.

9. The method according to claim 7 or 8 when dependent on claim 5, wherein When information is received indicating that the work vehicle is in excavation operation mode or driving operation mode, the method includes outputting a pilot pressure between the third pilot pressure and the fourth pilot pressure.

10. The method according to any one of claims 1 to 9 when dependent on claim 4 or 5, further comprising: Obtain position information indicating the position of the swing system and / or the position of the work vehicle; The drift braking torque applied by the drift brake is controlled based on the position information.

11. The method of claim 10, wherein The position information includes one or more of the yaw, pitch, and roll of the oscillation system and / or one or more of the yaw, pitch, and roll of the work vehicle.

12. A swing system controller for a swing system of a working machine, the swing system controller being configured to: Obtain the operating mode of the swing system; The pilot pressure output to the parking brake and drift brake of the oscillation system is controlled based on the operating mode, wherein the oscillation system controller is configured to cause the oscillation system to operate in the following manner: In a first configuration, a first pilot pressure causes the parking brake to be applied to the sway system and the drift brake to be unapplied to the sway system. In a second configuration, a second pilot pressure causes the parking brake not to be applied to the sway system and the drift brake not to be applied to the sway system, wherein the second pilot pressure is greater than the first pilot pressure. as well as In a third configuration, a third pilot pressure causes the parking brake not to be applied to the sway system and the drift brake to be applied to the sway system, wherein the third pilot pressure is greater than the second pilot pressure.

13. A swaying system for a work vehicle, the swaying system being configured to cause the upper body of the work vehicle to rotate relative to the lower body of the work vehicle, the swaying system comprising: A parking brake that can apply parking braking torque based on pilot pressure to counteract the rotation of the oscillating system; A drift brake, configured to apply a drift braking torque based on the pilot pressure to counteract the rotation of the oscillating system; The swing system controller according to claim 12.

14. The oscillating system according to claim 13, further comprising: A swing motor configured to cause the upper body of the work vehicle to rotate relative to the lower body of the work vehicle; as well as A hydraulic pump is configured to pump hydraulic fluid to the oscillating motor, causing the oscillating motor to rotate.

15. The oscillating system according to claim 14, wherein The hydraulic pump is connected to the hydraulic motor as a closed-loop hydraulic system.

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