Hydraulic pump actuator unit with a hydraulic actuator and a hydraulic pump

Abstract

Hydraulic pump actuator unit comprising at least one hydraulic actuator (3) for implementing a working movement and a hydraulic pump (4) for pressurizing the hydraulic actuator (3), as well as a closed hydraulic circuit (7, 8), wherein the hydraulic circuit (7, 8) comprises at least the hydraulic actuator (3) and the hydraulic pump (4) as well as a hydraulic fluid, wherein the hydraulic actuator (3) has at least a first actuator volume with a first actuator surface and a second actuator volume with a second actuator surface, wherein the hydraulic pump (4) has a pump shaft (10) and a pump housing (21), wherein a drive motor (9) is provided for driving the hydraulic pump (4) and / or the pump shaft (10),wherein a first connecting device (7) of the hydraulic circuit is provided between the first actuator volume and the pump housing (21), and a second connecting device (8) of the hydraulic circuit is provided between the second actuator volume and the pump housing (21), characterized in that at least one hydraulic motor (4) with a motor shaft (10) is arranged within / in the pump housing (21), wherein the pump shaft (10) is designed as the motor shaft (10), so that the pump housing (21) is designed as a common pump-motor housing (21) of the hydraulic pump (4) and the hydraulic motor (4).

Description

[0001] The invention relates to a mobile work machine and a hydraulic pump actuator unit having at least one hydraulic actuator for realizing a working movement and a hydraulic pump for pressurizing the hydraulic actuator, as well as a closed hydraulic circuit, wherein the hydraulic circuit comprises at least the hydraulic actuator and the hydraulic pump as well as a hydraulic fluid, according to the preamble of claim 1 or 15. State of the art

[0002] A wide variety of hydraulic drives are used in mobile machinery. A distinction is made between throttle control and positive displacement control. Throttle control is typically used when at least one pump and at least one valve block supply at least one consumer. In such systems, energy recovery is only possible with additional technology, and due to the large number of valves, it is still subject to significant losses, as the additional technology results in further flow losses.

[0003] In displacement control, a pump typically supplies an actuator. A distinction is made between open and closed circuits. In open circuits, the fluid is always pumped through a tank. This means that there is always a fixed high- and low-pressure side in the system. This variant has the disadvantage that additional valves are required for load maintenance or energy recovery. However, it has the advantage that the design can also be used for non-area-balanced actuators, such as differential cylinders.

[0004] The situation is different with positive displacement controls in a closed circuit, where the actuators are connected to the pump on both sides. The high and low pressure sides are adjusted depending on the load and direction of movement. The advantage here is that no valves are required for movement or load holding, and energy recovery in the form of regeneration or recuperation is possible directly via the pump. The disadvantage, however, is that the actuator volume flows supplied and discharged must be almost identical. This rules out the use of differential cylinders, for example, since a not insignificant portion of the volume flow must be added during the extending movement and removed from the circuit during the retracting movement. Otherwise, two pumps must be used separately, which is currently the standard design for such cases.

[0005] Due to cost-effectiveness, this setup is only known with two fixed-displacement pumps. However, these have the disadvantage that, due to their design, almost all fixed-displacement pumps cannot start up from a standstill against pressure, which is always the case with mobile machinery. Furthermore, with fixed-displacement pumps, the pump drive unit must be able to change its direction of rotation so that the actuators can move in both directions. Therefore, a separate electric motor would be virtually the only solution for fully operating actuators with differential volumes using two pumps in a semi-closed circuit.

[0006] Especially in mobile machinery such as excavators, loaders, dumpers, etc., differential cylinders are typically used for linear movements. These cylinders are characterized by a difference in the supplied and discharged volume flow, making closed-loop operation impossible without additional volume flow supply or discharge. At least one additional pump is required for the supply. Two fixed-displacement pumps with the appropriate displacement volume are often flanged together to compensate for the volume flow difference. Such a setup always requires a rotary drive for the pump assembly so that it can rotate both clockwise and counterclockwise and so that the linear unit can extend and retract. Object and advantages of the invention

[0007] The object of the invention is to propose a hydraulic pump actuator unit or a mobile work machine which at least partially improves the disadvantages of the prior art.

[0008] This object is achieved, based on a hydraulic pump-actuator unit or mobile work machine of the type mentioned in the introduction, by the features of claims 1 and 15, respectively. Advantageous embodiments and further developments of the invention are possible through the measures mentioned in the subclaims.

[0009] Accordingly, a hydraulic pump actuator unit according to the invention comprises at least one hydraulic actuator for realizing a working movement and a hydraulic pump for pressurizing the hydraulic actuator as well as a closed hydraulic circuit, wherein the hydraulic circuit comprises at least the hydraulic actuator and the hydraulic pump as well as a hydraulic fluid, wherein the hydraulic actuator has at least a first actuator volume with a first actuator surface and a second actuator volume with a second actuator surface, wherein the hydraulic pump has a pump shaft and a pump housing, wherein a drive motor is provided for driving the hydraulic pump and / or the pump shaft,wherein a first connecting device of the hydraulic circuit is provided between the first actuator volume and the pump housing, and a second connecting device of the hydraulic circuit is provided between the second actuator volume and the pump housing, wherein at least one hydraulic motor with a motor shaft is arranged within / in the pump housing, wherein the pump shaft is designed as the motor shaft, so that the pump housing is designed as a common pump-motor housing of the hydraulic pump and the hydraulic motor.

[0010] This measure significantly reduces both the design and constructional complexity and the control system complexity. This also leads to a cost-effective implementation of the invention. Thus, the hydraulic pump and the hydraulic motor are arranged or integrated within / in the shared pump-motor housing. This also saves space and volume and leads to dual use of the shared pump shaft and motor shaft. Consequently, the pump shaft and the motor shaft are designed as a shared pump-motor shaft. Accordingly, a single drive motor or electric motor is sufficient for the hydraulic pump and the hydraulic motor.

[0011] For example, the hydraulic pump drives both the hydraulic actuator of the closed hydraulic circuit and the hydraulic motor. This improves the energy balance of the system or the closed hydraulic circuit.

[0012] It is generally conceivable that in alternating operation in a first operating mode, the hydraulic pump drives both the hydraulic actuator of the closed hydraulic circuit and the hydraulic motor, and in a second operating mode, the hydraulic pump and the hydraulic motor change or swap their function or mode of operation. Thus, the (first) hydraulic pump (of the first operating mode) can be configured as a (second) hydraulic motor pump (of the second operating mode), and the (first) hydraulic motor (of the first operating mode) can be configured as a (second) hydraulic pump (of the second operating mode). This results in completely new functionalities and modes of operation for the hydraulic actuator to implement its working movement. This improves both the energy and economic balance of the hydraulic pump-actuator unit.

[0013] For example, at least one first and / or second pump bearing for supporting the pump shaft is designed as a first and / or second motor bearing for supporting the motor shaft. This allows for the shared pump-motor shaft to be supported without great effort. Thus, in the aforementioned operating mode with alternating functionality of the hydraulic pump and hydraulic motor, the effort and costs can be significantly reduced or even minimized, and the energy or economic efficiency can be increased or even maximized, by combining two hydraulic pumps or two hydraulic motors in a common housing with shared bearings and, if necessary, a shared control or positioning system.

[0014] Optionally, the first actuator volume is (approximately) the same size as the second actuator volume and / or the first actuator surface is (approximately) the same size as the second actuator surface. For example, the first actuator volume is larger than the second actuator volume and / or the first actuator surface is larger than the second actuator surface. For example, the hydraulic actuator can be designed as a double-acting reciprocating piston unit, in particular as a double-acting differential cylinder, with a high-pressure side and a low-pressure side. Optionally, the low-pressure side is designed as the suction side. This allows hydraulic actuators or double-acting reciprocating piston units, such as especially double-acting differential cylinders, which are already widely used in mobile work machines for a wide variety of functionalities or working movements to be used in a special way according to the invention.

[0015] For example, at least one actuating unit is provided for adjusting the first actuator volume and / or the second actuator volume and / or the first actuator area and / or the second actuator area. This measure opens up completely new or expanded possibilities or functionalities of the hydraulic pump actuator unit according to the invention. Thus, the volumes can be changed or adapted to specific / individual applications and / or operating methods.

[0016] For example, the actuating unit is arranged within / in the pump housing and / or the common pump-motor housing. This achieves a special integration and tightness of the hydraulic pump-actuator unit according to the invention. For example, the actuating unit has at least one hydraulic actuating element for hydraulic adjustment. This measure enables hydraulic adjustment.

[0017] For example, the hydraulic actuator is oriented at an angle, particularly an acute angle, relative to the pump shaft and / or motor shaft, wherein the angle is, in particular, variable. This allows the first and / or second actuator volume to be adjusted or set in a particular manner, i.e., by means of the angle.

[0018] For example, the actuator is designed to be rotatable, particularly driven by the pump motor, with a pump speed corresponding to a control element speed. If appropriate, the rotational axis or drive axis of the actuator or control unit is designed as the pump shaft and / or motor shaft. This significantly minimizes the design and cost-effectiveness.

[0019] For example, the hydraulic pump is arranged on a first side of the actuator unit and / or hydraulic actuator, and the hydraulic motor is arranged on a second side, opposite the first side. This allows for a particularly compact and space-saving design, especially within / in the shared housing.

[0020] For example, the hydraulic pump is arranged on a first radius and / or at a first distance from the pump / motor shaft, and the hydraulic motor is arranged on a second radius and / or at a second distance from the pump / motor shaft. If necessary, the two radii are the same size, so that both components are arranged at the same distance from the shaft / axis. With the same actuating stroke / distance, the same volume is generated by the pump and motor. Alternatively, with different actuating strokes / distances, different volumes can be generated by the pump and motor. The latter is particularly helpful in applications with different displacement volumes, such as double-acting hydraulic cylinders, etc.

[0021] For example, the first radius and / or distance is larger than the second radius and / or distance. Alternatively, or in combination with this, a pump working volume can be designed larger or smaller than a motor working volume. Likewise, a pump cross-sectional area of the pump working volume can be designed larger or smaller than a motor cross-sectional area of the motor working volume. These measures can also be used to generate different pump and motor volumes.

[0022] In general, a pivoting pump or pump-motor unit with two different displacement volumes, equipped with a common adjustment system, can be used to precisely control the required amount of fluid, for example, a differential cylinder. For this purpose, the two displacement volumes are in the same ratio as the two cylinder surfaces of the actuator.

[0023] In addition, a feed pump can be integrated into such a double pump if necessary, for example to pressurize the system with a minimum pressure. With this design, both displacement volumes are connected, for example, once to a cylinder chamber and once to the tank. This means that it is not a classic pump in a closed circuit, but two pumps with a shared control system in a semi-closed circuit. This design enables both regeneration and recuperation, and the pivoting capability means that the linear drive can be extended and retracted without having to change the direction of rotation of the pump drive. For example, a pump with a piston design is constructed in this way.

[0024] In principle, the following designs can be implemented individually or in combination with one another for a structure according to the invention or a so-called double pump structure: • "Back-to-back" design: This uses separate piston drums for both displacement volumes, with the piston shoes facing each other. The common adjustment system is located between them, for example, to synchronously adjust the swivel angle. The volumetric flow differential ratio can be adjusted by varying the piston pitch diameter and piston diameter. • "Both displacement volumes in one piston drum with different pitch circle diameters": Here, too, the volume flow differential ratio can be adjusted, for example, by varying the piston pitch circle diameter and piston diameter. All piston shoes are supported on one side by the actuating system. • "Both displacement volumes in one piston drum with the same pitch circle diameter": Here, for example, the volume flow differential ratio can be adjusted simply by varying the piston diameter. Again, all piston shoes, for example, are supported on one side of the actuating system.

[0025] All of the above solutions have in common, for example, that only one common pump housing with a common control system and common bearings is required, even though two displacement volumes that are different in a fixed ratio to one another are available. If required, an additional feed pump can be integrated, for example, so that a minimum pressure can be maintained for both high / pressure sides. The control system should be designed to be as oscillatory as possible; this would then allow, for example, a cylinder drive to extend and retract without the pump drive having to change direction. This could also be used, for example, in diesel engines or in a pump network. If it is not designed to be oscillatory, the direction can be changed using the direction of rotation of the drive unit.

[0026] Ultimately, a control system is not absolutely necessary if, for example, the drive motor can operate at a variable speed. The actuator speed can then be adjusted if, for example, the pump has a fixed swivel angle. So that the actuator can move in both directions, the drive motor should also be able to operate in both directions of rotation. Ultimately, these properties - a variable-speed drive motor that can be operated in two directions of rotation, if necessary, and a pump with fixed or variable displacement volumes (possibly also capable of swiveling) - could be combined in such a way that it is suited to the respective task. This also results in control strategy options, for example to operate the drive motor and displacement unit using a so-called "best point strategy". Example

[0027] An embodiment of the invention is shown in the drawing and is explained in more detail below with reference to the figures. Fig. 1 a schematic sectional view of a first hydraulic pump-actuator unit according to the invention, Fig. 2 a schematic sectional view of a second hydraulic pump actuator unit according to the invention and Fig. 3 a schematic circuit symbol for hydraulic pump-actuator units according to the invention.

[0028] In the Fig. 1, Fig. 2 and Fig. In Figure 3, the same reference numerals are used for similar or similarly functioning components / elements, and a hydraulic pump-actuator unit according to the invention is schematically illustrated in different ways or designs. The hydraulic pump-actuator unit comprises a differential cylinder 3 and a hydraulic pump-motor unit 4 or a piston drum 4. The hydraulic pump-motor unit 4 or piston drum 4 has a housing 21 and can be driven or rotated by means of a drive shaft 10, e.g., by an electric motor 9 (see Figure 3). Fig. 3). The drive shaft 10 is rotatably supported by means of roller bearings 20.

[0029] The differential cylinder 1 has a first cylinder chamber 1 and a second cylinder chamber 2, between which a piston 5 with a piston rod 6 is arranged. Due to the piston rod 6, on the one hand, a cylinder pressure area of a rod side or second cylinder chamber 2 is smaller than a cylinder pressure area of a piston side 1 or first cylinder chamber 1. On the other hand, due to the piston rod 6, a displacement volume V2 of the rod side 2 or second cylinder chamber 2 is smaller than a displacement volume V1 of the piston side 1 or first cylinder chamber 1.

[0030] A first hydraulic connecting line 7 is provided between the differential cylinder 1 or the first cylinder chamber 1 and the hydraulic pump-motor unit 4 or a first displacement piston cylinder 11, and a second hydraulic connecting line 8 is provided between the differential cylinder 1 or the second cylinder chamber 2 and the hydraulic pump-motor unit 4 or a second displacement piston cylinder 12. In addition, compensating cylinders 13 are provided, between which hydraulic fluid / oil can flow and which have a differential volume compensation 14 via a tank 15.

[0031] In addition, an actuating system 30 is provided, which adjusts or drives the first displacement piston cylinder 11 and second displacement piston cylinder 12, as well as the compensating cylinder 13, with the aid of an actuating disc 31 arranged at an angle or acute angle relative to the drive shaft 10. The aforementioned cylinders 11, 12, 13 each have adjustably mounted piston shoes 32 on the actuating disc 31. Upon rotation of the drive shaft 10, the pistons of the aforementioned cylinders 11, 12, 13 are each adjusted or perform a stroke adjustment / movement, so that hydraulic fluid is pressurized accordingly. Accordingly, a hydraulic pump function on the one hand and a hydraulic motor function on the other are realized within the housing 21 or by the hydraulic pump-motor unit 4 or piston drum 4.

[0032] Since the displacement volumes V1 and V2 are different or of different sizes, the cylinders 11, 12, 13 mentioned above must also be designed differently. For this purpose, for example, as shown in Fig. 1 a) and Fig. 1 c) the cylinders 11, 12, 13 are arranged on correspondingly different radii R1, R2 in order to depict or reflect the ratio of displacement volume V1 to displacement volume V2 as accurately as possible. In this case, according to the variant of the Fig. 1 a) and Fig. 1 c) the pistons of the cylinders 11, 12, 13 are designed with the same piston diameters, but on the one hand on an inner circular path with (small) radius R2 and on the other hand on an outer circular path with (larger) radius R1.

[0033] Alternatively, the piston diameters of the cylinders 11, 12, 13 can be designed differently (largely), if these are, for example, according to the variant of the Fig. 1 b) are arranged on an identical or the same radius.

[0034] In the variant according to Fig. 2, the cylinders 11, 12, 13 or the corresponding piston shoes 32 are arranged on both sides of the adjusting disc 31. Here, too, as in the variant of the Fig. 1 a) and 1 c) with different radii R1 and R2 the ratio of the different displacement volumes V1 and V2 is depicted / realized accordingly.

[0035] In general, the actuating system 30 or the actuating disc 31 can be designed to be variable. For example, by changing or adjusting the angle between the disc plane and the drive axis 10, i.e., by adjusting the alignment of the actuating disc 31, a change in the pump volume or pump power generated / displaced by the rotation of the drive shaft 10, as well as in the generated motor volume or motor power, can be achieved. The speed and / or angle of the actuating disc 31, for example, can be used as adjustment parameters.

Claims

[1] Hydraulic pump actuator unit with at least one hydraulic actuator (3) for realizing a working movement and with a hydraulic pump (4) for pressurizing the hydraulic actuator (3) as well as with a closed hydraulic circuit (7, 8), wherein the hydraulic circuit (7, 8) comprises at least the hydraulic actuator (3) and the hydraulic pump (4) as well as a hydraulic fluid, wherein the hydraulic actuator (3) has at least a first actuator volume with a first actuator surface and a second actuator volume with a second actuator surface, wherein the hydraulic pump (4) has a pump shaft (10) and a pump housing (21), wherein a drive motor (9) is provided for driving the hydraulic pump (4) and / or the pump shaft (10),wherein a first connecting device (7) of the hydraulic circuit is provided between the first actuator volume and the pump housing (21), and a second connecting device (8) of the hydraulic circuit is provided between the second actuator volume and the pump housing (21), characterized by that at least one hydraulic motor (4) with a motor shaft (10) is arranged within / in the pump housing (21), wherein the pump shaft (10) is designed as the motor shaft (10), so that the pump housing (21) is designed as a common pump-motor housing (21) of the hydraulic pump (4) and the hydraulic motor (4). [2] Hydraulic pump actuator unit according to claim 1, characterized by that at least one first and / or second pump bearing (20) for supporting the pump shaft (10) is designed as a first and / or second motor bearing (20) for supporting the motor shaft (10). [3] Hydraulic pump actuator unit according to one of the preceding claims, characterized by that the first actuator volume is larger than the second actuator volume and / or the first actuator area is larger than the second actuator area. [4] Hydraulic pump actuator unit according to one of the preceding claims, characterized by that the hydraulic actuator (3) is designed as a double-acting piston unit (3), in particular as a double-acting differential cylinder (3), with a high-pressure side and a low-pressure side. [5] Hydraulic pump actuator unit according to one of the preceding claims, characterized by that at least one actuating unit (30) is provided for adjusting the first actuator volume and / or the second actuator volume and / or the first actuator surface and / or the second actuator surface. [6] Hydraulic pump actuator unit according to one of the preceding claims, characterized bythat the actuating unit (30) is arranged within / in the pump housing (21) and / or the common pump-motor housing (21). [7] Hydraulic pump actuator unit according to one of the preceding claims, characterized by that the actuating unit (30) has at least one hydraulic actuating element (31) for hydraulic adjustment. [8] Hydraulic pump actuator unit according to one of the preceding claims, characterized by that the hydraulic actuating element (31) is aligned at an actuating angle with respect to the pump shaft (10) and / or motor shaft (10), wherein in particular the actuating angle is variable. [9] Hydraulic pump actuator unit according to one of the preceding claims, characterized by that the actuating element (31) is designed to be rotatable, in particular driven by the pump motor (9), wherein in particular a pump speed corresponds to an actuating element speed. [10] Hydraulic pump actuator unit according to one of the preceding claims, characterized by that the hydraulic pump (4) is arranged on a first side of the actuating unit (30) and / or the hydraulic actuating element (31) and that the hydraulic motor (4) is arranged on a second side opposite the first side. [11] Hydraulic pump actuator unit according to one of the preceding claims, characterized by that the hydraulic pump (4) is arranged on a first radius (R1) and / or at a first distance from the pump / motor shaft (10) and that the hydraulic motor (4) is arranged on a second radius (R2) and / or at a second distance from the pump / motor shaft (10). [12] Hydraulic pump actuator unit according to one of the preceding claims, characterized by that the first radius (R1) and / or distance is greater than the second radius (R2) and / or distance. [13] Hydraulic pump actuator unit according to one of the preceding claims, characterized by that a pump working volume is larger or smaller than a motor working volume. [14] Hydraulic pump actuator unit according to one of the preceding claims, characterized by that a pump cross-sectional area of the pump working volume is larger or smaller than a motor cross-sectional area of the motor working volume. [15] Mobile work machine, in particular wheel loader, telescopic loader, excavator, dumper, soil compaction device such as a vibratory rammer, a vibrating plate or a roller, or the like, with a supporting frame and with a drive unit for driving at least one drive element and with a hydraulic pump actuator unit according to one of the preceding claims.

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