Mechanical-hydraulic coupling

Abstract

The present invention relates to a mechanical-hydraulic coupling, between a drive shaft (1) and a driven shaft (2) that are coaxial to each other, comprising a pumping chamber (6) solidly attached to the driven shaft (2) and containing a main gear (4) connected to the drive shaft (1) and one or more planetary gears (5), freely rotating and articulated on the pumping chamber (6), forming gear pumps. The coupling is further provided with a hydraulic circuit formed by a tank (31), a suction tube (32) that connects the tank (31) to the inlet of the gear pumps, a pressure chamber (33) downstream of the gear pumps, with a return tube (34) from the pressure chamber (33) to the tank (31) and wherein the return tube (34) has a pressure control valve (35).

Description

[0001] DESCRIPTION

[0002] Mechanical-hydraulic coupling

[0003] OBJECT OF THE INVENTION

[0004] The invention, as the title of this specification indicates, is a mechanical-hydraulic coupling that allows torque and speed to be transmitted between coaxial shafts, with its operation easily controlled. It can, for example, operate to vary the output torque, from complete decoupling to transmission with virtually no losses.

[0005] STATE OF THE ART

[0006] There are many known designs of mechanical couplings in the state of the art that allow torque and speed to be transferred from one shaft to another. Some of these couplings also allow the shafts to be decoupled, functioning as clutches.

[0007] This type of coupling comprises a whole range of mechanical elements and moving parts that can wear out and break down in various ways.

[0008] Currently, the existence of any coupling that presents structural and constitutive technical characteristics equal to or similar to those described in this specification is unknown.

[0009] DESCRIPTION OF THE INVENTION

[0010] The object of the present invention is the creation of a mechanical-hydraulic coupling that provides a notable innovation within its field of application in the current state of the art, the characterizing details that make it possible being conveniently included in the final claims that accompany this description.

[0011] The present invention relates to a mechanical-hydraulic coupling that incorporates mechanical parts and hydraulic elements that, among others, perform mechanical and lubrication functions, reducing wear.

[0012] The mechanical-hydraulic coupling between a drive shaft and a driven shaft, coaxial with each other, comprises a mechanical part and a hydraulic part. The mechanical part is a pumping chamber, integral with the driven shaft, and generally cylindrical in shape. The pumping chamber contains a positive displacement pump, for example, formed by a main gear connected to the drive shaft, and planetary gears, freely rotating and articulated on the pumping chamber. These elements, the positive displacement pump and the pumping chamber, form gear pumps. To ensure symmetry and compensation of radial forces, it advantageously comprises two or more planetary gears arranged rotationally symmetrically with respect to the main gear.

[0013] The hydraulic component is a hydraulic circuit consisting of a reservoir (internal or external), for example, a cylindrical reservoir, a suction pipe connecting the reservoir to the inlet of the gear pumps, a pressure chamber after the gear pumps, with a return pipe from the pressure chamber to the reservoir. The return pipe also has a pressure-regulating valve (e.g., a relief valve) if it is used as a torque regulator. This valve opens automatically if the pressure difference on both sides exceeds a predefined value.

[0014] Some of the advantages of this invention are:

[0015] It allows the engines to start without load, subsequently leaving the desired speed or power.

[0016] It allows a given engine torque to be maintained without overloading the engine due to an increase in the resistance of the output shaft.

[0017] The output speed can be varied independently of the engine speed, allowing this speed to be changed at any time. This can thus replace the complex Ward Leonard system.

[0018] Similarly, the speed of the combustion engine can be varied depending on the power required, so that it operates at the optimal speed to produce the desired power, thereby reducing fuel consumption.

[0019] In one embodiment, as a variation of the main solution, the planetary gears are of a different radius than the main gear.

[0020] A preferred embodiment comprises an auxiliary circuit with a turbine or hydraulic machine connected hydraulically to the pressure chamber and mechanically to the driven shaft. The outlet of this auxiliary circuit is connected to the reservoir through a second valve, preferably also a pressure regulator. This allows part of the pressure in the turbine to be recovered for other uses.

[0021] Other ways of carrying out the invention are shown below.

[0022] EXPLANATION OF THE FIGURES

[0023] To complete the description being made and in order to help better understand the characteristics of the invention, a section of drawings is presented where, for illustrative and non-limiting purposes, the following have been represented.

[0024] Figure 1 corresponds to an exploded view of the mechanical part of the coupling with internal tank according to an embodiment example.

[0025] Figures 2 and 3 correspond to a partially exploded side view of the example in Figure 1.

[0026] Figures 4 and 5 correspond to a section of a second embodiment, with external tank

[0027] PREFERRED EMBODIMENT OF THE INVENTION.

[0028] The coupling example shown in the figures comprises a drive shaft (1 ), connected to the motor or element that generates the torque, a driven shaft (2 ), connected to the destination of that torque, a hydraulic circuit, with a tank (31 ), a suction tube (32), a pressure chamber (33) with a return tube (34) from the pressure chamber (33) to the tank (31 ) and where the return tube (34) has a pressure regulating valve (35). The hydraulic fluid, by definition, will be incompressible. The tank (31 ) may be pressurized (for example, by a membrane) so that the fluid tends to fill the tubes (32,34).

[0029] The coupling also has a main gear (4) connected to the drive shaft (1) and a series of planetary gears (5) meshed with the main gear (4), inside a pumping chamber (6) with a positive displacement pump. The pumping chamber (6) is connected to the driven shaft (2), such that it rotates with it. The planetary gears (5) are articulated to the pumping chamber (6), with freedom of rotation. The set of gears (4,5) and the pumping chamber (6) form separate gear pumps that push the hydraulic fluid to the pressure chamber (33). The planetary gears (5) can have a different radius than the main gear (4), thus modifying the torque. In figures 1, 2 and 3, the tank (31) is included within the cylindrical element that comprises the pumping chamber (6).The tank (31) may have moving elements that reduce its dimensions, such as a moving wall or membrane, pushed by one or more mechanical, hydraulic or pneumatic springs.

[0030] The planetary gears (5) are preferably two or more and have rotational symmetry with respect to the main gear (4) to balance forces. The gears (4,5) are in a pumping chamber (6) connected on one side to the suction pipe (32) and on the other to the pressure chamber (33). Thus, the gears (4,5) produce the movement of the hydraulic fluid, from the tank (31) to the pressure chamber (33).

[0031] The regulating valve (35) is configured to open when a pressure value is exceeded in the pressure chamber (33) and close when it is not reached. It can also be opened voluntarily or comprise a deviation or by-pass that allows the pressure chamber (33) to be emptied into the tank (31). Figures 1, 2 and 3 show a control knob (39) whose distance from the pumping chamber (6) defines the pressure of the regulating valve (35). In this figure, two regulating valves (35) are arranged, since the pumping chamber (6) has two planetary gears (5) and two fluid outlets to the tank (31) coaxial to the pumping chamber (6) and to the shafts (1, 2).

[0032] The suction pipe (32) may have a flow regulator to reduce, if desired, the flow of hydraulic fluid entering the pumping chamber (6). However, it is not always desirable to be able to completely cut off the flow. It may also have a non-return or check valve (30).

[0033] The entry and exit of the hydraulic fluid to the pumping chamber (6) can be carried out by coaxial passages to the respective axes (1,2), with the external oil tank, figures 4, 5.

[0034] In use, when the drive shaft (1) rotates, it produces movement of the main gear (4) and the planetary gears (5), which act as hydraulic pumps. Depending on the state of the valve (35) or the deviation:

[0035] If the passage from the pressure chamber (33) to the tank (31 ) is open, the drive shaft (1 ) moves the hydraulic pumps and the fluid flows freely. The planetary gears (5) rotate freely and do not transmit movement to the pumping chamber (6) and the driven shaft (2) remains stationary. The coupling is therefore working as a disengaged clutch. This position is optimal for starting the engine.

[0036] If the valve (35) is closed, only allowing the passage of fluid if the pressure is very high, the planetary gears (5) drive the fluid towards the pressure chamber (33), suffering a reaction force when the internal pressure reaches the pressure defined in the valve (35). This reaction is transmitted to the pumping chamber (6) which rotates, dragging the driven shaft (2) with it. It must be considered that the valve (35) can remain closed for these purposes, if the defined pressure is sufficiently high.

[0037] Unlike a traditional gearbox, this coupling does not increase torque when the driven shaft (2) is turning at low speeds. Instead, a lot of hydraulic fluid flows through the hydraulic circuit. An alternative is to increase the pressure of the valve (35) but include an auxiliary circuit with a turbine or a hydraulic machine (36) that recovers part of the pressure to generate torque that is supplied to the driven shaft (2) by means of an auxiliary gear. The output of the hydraulic machine (36) reaches the tank (31) through a second valve (37) that can also be a pressure regulator. The opening of this second valve (37) defines how much energy is extracted by the hydraulic machine (36)

[0038] Ideally, the valve (35) is adjustable so that the user, or an automatic system, can modify the pressure at which the valve (35) is activated and, consequently, the reaction force suffered by the planetary gears (5) and the torque received by the driven shaft (2). The automatic system can vary the torque received by the driven shaft (2) by touching the torque of the drive shaft (1) or the opening pressure of the valve (35). Consequently, it can act as an automatic gear changer. In return, the element that moves the drive shaft (1) can remain in the optimal working regime.

[0039] The rotational speed of the driven shaft (2) will depend on the speed of the fluid and the drive shaft (1). When the fluid is moving at maximum speed, the driven shaft (2) does not rotate. The less it moves, the more torque is transmitted.

[0040] The person skilled in the art will appreciate that the valves (35, 37) can have different positions, so that the fluid can pass through one or both at different opening pressures. For example, the valve (35) can be closed and the second valve (37) can be fully opened, so that it is the hydraulic machine (36) that does the work. The dimension of the hydraulic machine (36) defines whether the output torque is greater or less than the input torque.

[0041] In automatic vehicle transmissions, if the driven axle (2), for any reason, turns at a speed greater than that provided by the drive axle (1), the gears (4,5) will turn in the opposite direction and the fluid will travel through the circuit in the opposite direction until the suction pipe valve (32) closes (for example by the non-return valve (30) already mentioned). At that moment, the coupling will become rigid again, with the engine brake working. If necessary, the hydraulic machine (36) can also be used in the opposite direction to brake, when moved by the driven axle (2), functioning as a pump. In this case, it will take the fluid from the tank to carry it to the pressure chamber (33) in the opposite direction to the flow already described. This hydraulic machine (36) therefore absorbs energy from the driven axle (2), according to the resistance exerted by the valves of its circuit.

[0042] It can be seen that several of the mechanical parts of the coupling are immersed in hydraulic fluid, which may be oil. Thus, for example, the gears (4, 5) are lubricated while they operate.

Claims

CLAIMS 1- Mechanical-hydraulic coupling, between a drive shaft (1 ) and a driven shaft (2), coaxial, characterized in that it comprises: a pumping chamber (6), integral with the driven shaft (2) and containing a positive displacement pump; a hydraulic circuit formed by a tank (31 ), a suction tube (32) that connects the tank (31 ) with the inlet of the positive displacement pump, a pressure chamber (33) after the gear pumps, with a return tube (34) from the pressure chamber (33) to the tank (31 ) and where the return tube (34) has a pressure regulating valve (35); 2- Mechanical-hydraulic coupling, according to claim 1, characterized in that the positive displacement pump is a main gear (4) connected to the drive shaft (1) and two or more planetary gears (5), free-rotating and articulated on the pumping chamber (6). 3- Mechanical-hydraulic coupling, according to claim 2, characterized in that the planetary gears (5) have a different radius than the main gear (4). 4- Mechanical-hydraulic coupling, according to claim 2, characterized in that it comprises two or more planetary gears (5) arranged with rotational symmetry with respect to the main gear (4). 5- Mechanical-hydraulic coupling, according to claim 1, characterized in that the valve (35) has a by-pass. 6- Mechanical-hydraulic coupling, according to claim 1, characterized in that the entry and exit of the hydraulic fluid to the pumping chamber (6) is carried out by coaxial passages to the respective axes (1,2). 7- Mechanical-hydraulic coupling, according to claim 1, characterized in that the valve (35) is adjustable in opening pressure. 8- Mechanical-hydraulic coupling, according to claim 1, characterized in that it comprises an auxiliary circuit with a turbine or a hydraulic machine (36), connected to the pressure chamber (33) and to the driven shaft (2), its output being connected to the tank (31) through a second valve (37). 9- Mechanical-hydraulic coupling, according to claim 8, characterized in that the second valve (37) is a pressure regulator. 10- Mechanical-hydraulic coupling, according to claim 1, characterized in that the suction tube (32) comprises a non-return valve (30).

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