HYDRAULIC STEERING UNIT FOR A BOAT DRIVE AND BOAT DRIVE WITH SUCH A STEERING UNIT

Abstract

A boat drive hydraulic steering unit has a steering cylinder unit, pump and tank. The cylinder unit has a first chamber, piston and second chamber. The pump is connected to the first and second chambers by respective first and second line. The first chamber is connected to the tank via the first line arrangement when the second chamber is pressurized, by the first line arrangement having a first check valve which opens when the second line arrangement is pressurized. The second chamber is connected to the tank via the second line arrangement when the first chamber is pressurized, by the second line arrangement having a second check valve which opens when the first line arrangement is pressurized. The first and second line arrangements have respective first and second throttling devices acting in the direction of flow towards the tank. A boat drive may include the steering unit.

Claims

1. A hydraulic steering unit for a boat drive, comprising: at least one steering cylinder unit having a first piston chamber, a cylinder piston unit and a second piston chamber separated from the first piston chamber by the cylinder piston unit; at least one pump connected to the first piston chamber via a first line arrangement and to the second piston chamber via a second line arrangement; a tank; the first piston chamber being connected to the tank via the first line arrangement when the second piston chamber is pressurized, in that the first line arrangement has a first check valve which is opened when the second line arrangement is pressurized; and the second piston chamber being connected to the tank via the second line arrangement when the first piston chamber is pressurized, in that the second line arrangement has a second check valve which is opened when the first line arrangement is pressurized; wherein; the first line arrangement has a first throttling device acting in a direction of flow to the tank, and the second line arrangement has a second throttling device acting in a direction of flow to the tank.

2. The hydraulic steering unit according to claim 1, wherein the first throttling device comprises a first hydraulic resistor.

3. The hydraulic steering unit according to claim 2, wherein the first hydraulic resistor is a first nozzle.

4. The hydraulic steering unit according to claim 3, wherein: the first nozzle is an adjustable nozzle in a closing direction and an opening direction; a first control line branches off from the second line arrangement and acts on the first nozzle in the opening direction; and a second control line branches off from the first line arrangement between the first piston chamber and the first nozzle and acts on the first nozzle in the closing direction.

5. The hydraulic steering unit according to claim 4, wherein the second throttling device comprises a second hydraulic resistor.

6. The hydraulic steering unit according to claim 5, wherein the second hydraulic resistor is a second nozzle.

7. The hydraulic steering unit according to claim 6, wherein: the second nozzle is a nozzle which is adjustable in a closing direction and in an opening direction; a third control line branches off from the first line arrangement and acts on the second nozzle in the opening direction; and a fourth control line branches off from the second line arrangement between the second piston chamber and the second nozzle and acts on the second nozzle in the closing direction.

8. The hydraulic steering unit according to claim 1, wherein: the first throttling device comprises a first pressure valve; a first signal line branches off from the first line arrangement between the first piston chamber and the first pressure valve and acts on the first pressure valve in an opening direction, a second signal line branches off from the first line arrangement between the first pressure valve and the tank and acts on the first pressure valve in a closing direction; and a first control line branches off from the second line arrangement and acts on the second pressure valve in the opening direction.

9. The hydraulic steering unit according to claim 1, wherein: the second throttling device has a second pressure valve; a third signal line branches off from the second line arrangement between the second piston chamber and the second pressure valve and acts on the second pressure valve in an opening direction; a fourth signal line branches off from the second line arrangement between the second pressure valve and the tank and acts on the second pressure valve in a closing direction; and a third control line branches off from the first line arrangement and acts on the second pressure valve in the opening direction.

10. The hydraulic steering unit according to claim 4, wherein: a third hydraulic resistor is disposed in the first control line; and/or a fourth hydraulic resistor is disposed in the third control line.

11. The hydraulic steering unit according to claim 1, wherein: the first throttling device has a first bypass line acting in a direction of flow to the first piston chamber.

12. The hydraulic steering unit according to claim 11, wherein a first bypass check valve is disposed in the first bypass line.

13. The hydraulic steering unit according to claim 11, wherein: the second throttling device has a second bypass line acting in a direction of flow to the second piston chamber.

14. The hydraulic steering unit according to claim 13, wherein a second bypass check valve is disposed in the second bypass line.

15. A boat drive, comprising a hydraulic steering unit according to claim 1.

16. The boat drive of claim 15, wherein the boat drive is an outboard motor or a Z-drive.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In the following, the invention is explained in more detail with reference to exemplary embodiments shown in the figures. The figures show schematically:

[0023] FIG. 1 a boat with a boat drive in a first steering situation;

[0024] FIG. 2 the boat according to FIG. 1 in a second steering situation;

[0025] FIG. 3 a hydraulic circuit diagram of an inventive hydraulic steering unit in accordance with a first embodiment;

[0026] FIG. 4 a hydraulic circuit diagram of an inventive hydraulic steering unit in accordance with a second embodiment;

[0027] FIG. 5 a hydraulic circuit diagram of an inventive hydraulic steering unit in accordance with a third embodiment; and

[0028] FIG. 6 a hydraulic circuit diagram of an inventive hydraulic steering unit in accordance with a modification of the embodiment shown in FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

[0029] FIGS. 1 and 2 schematically show a boat 100 with a boat drive 101, for example a Z-drive or an outboard motor. The boat 100 is in particular a leisure boat or sport boat. In the situation shown, the boat 100 travels in the direction of travel BR against the direction of flow FR of the water. For steering the boat 100, the boat drive 101 has a hydraulic steering unit 1a-1d, which is explained in more detail below with reference to FIG. 3 and FIG. 4.

[0030] In the steering situation shown in FIG. 1, the boat drive 101 is to be moved from the deflected position AS shown in dashed lines to the middle position MS. Here, an additional external force F.sub.ext generated by the flow direction FR of the water acts on the boat drive 101 in the direction of the middle position MS. As shown in FIG. 2, an external force F.sub.ext due to the flow direction FR of the water also acts on the boat drive 101 when the boat drive 101 is steered from the center position MS to a deflected position AS. As explained above, this external force F.sub.ext can cause problems when using a conventional hydraulic steering unit.

[0031] With the hydraulic steering units 1a-1d shown as hydraulic circuit diagrams in FIGS. 3 to 6 according to the invention, such problems can be prevented.

[0032] As shown in FIG. 3, the hydraulic steering unit 1a according to the first embodiment has a steering cylinder unit 2 configured as a synchronized cylinder with a first piston chamber 5 and a second piston chamber 6. The first piston chamber 5 is separated from the second piston chamber 6 by a cylinder piston unit configured as a single cylinder piston 7. As can be seen from FIG. 3, the cylinder piston 7 has two piston rods extending in opposite directions from the steering cylinder unit 2. For pressurizing the first piston chamber 5 and the second piston chamber 6 and thus for moving the cylinder piston 7 (and thus for moving the boat drive 101 relative to the hull of the boat 100 by means of the piston rods), the steering unit 1 further comprises a reversible pump 3 and a tank 4.

[0033] The pump 3 is driven by a motor M and is connected to the first piston chamber 5 via a first line arrangement 8. The pump 3 is connected to the second piston chamber 6 via a second line arrangement 9. A controllable first check valve 10 and a first throttling device 12a are dispsoed in the first line arrangement 8. The first check valve 10 is connected to the second line arrangement 9 via a first opening line 27 in such a way that pressurization of the second line arrangement 9 hydraulically opens the first check valve 10. Accordingly, a controllable second check valve 11, which is connected to the first line arrangement 8 via a second control line 28, and a second throttling device 13a are arranged in the second line arrangement 9. Thus, the second check valve 11 is hydraulically opened when pressure is applied to the first line arrangement 8.

[0034] The pump 3 as well as the first line arrangement 8 and the second line arrangement 9 are connected to the tank 4 via a pressure-controlled selector valve 26. Depending on the delivery direction of the pump 3, either the first line arrangement 8 or the second line arrangement 9 can be pressurized.

[0035] The first throttling device 12a acting in the direction of flow towards the tank 4 is disposed upstream of the first check valve 10, as seen in the direction of flow towards the tank 4, and has a first hydraulic resistor in the form of a first nozzle 14a. The first throttling device 12a has a first bypass line 18 acting in the direction of flow towards the first piston chamber 5 and having a first bypass check valve 19. In this embodiment, the first bypass check valve 19 is spring-loaded. As shown, the first bypass line 18 bypasses the first nozzle 14a when the first line arrangement 8 or the first piston chamber 5 is pressurized.

[0036] Accordingly, the second throttling device 13a acting in the direction of flow to the tank 4 is disposed upstream of the second check valve 11, as seen in the direction of flow to the tank 4. The second throttling device 13a has a second hydraulic resistor in the form of a second nozzle 15a. The second throttling device 13a has a second bypass line 24 acting in the direction of flow towards the second piston chamber 6 and having a second bypass check valve 25, which is also spring-loaded. As shown, the second bypass line 24 bypasses the second nozzle 20 when pressurizing the second line arrangement 9 or the second piston chamber 6.

[0037] A first return line 33 with a first pressure relief valve 34 branches off from the first line arrangement 8 upstream of the first throttling device 12a, as seen in the direction of flow to the tank 4. The first return line 33 is connected to the tank 4. Accordingly, a second return line 35 branches off from the second line arrangement 9 upstream of the second throttling device 13a, as seen in the direction of flow to the tank 4. The second return line 35 is connected to the tank 4 and has a second pressure relief valve 36.

[0038] A steering movement by pressurizing the first piston chamber 5 is now described below.

[0039] For this purpose, the pump 3 or the motor M is controlled in such a way that the first line arrangement 8 is pressurized. The selector valve 26 blocks the connection of the first line arrangement 8 to the tank 4 and connects the second line arrangement 9 to the tank 4. The first check valve 10 is opened by the pressure in the first line arrangement 8. At the same time, the pressure in the first line arrangement is signaled to the second check valve 11 via the second control line 28, so that the second check valve 11 is also opened. As soon as the back pressure upstream of the first nozzle 14 is correspondingly high and the spring force of the first bypass check valve 19 is overcome, the first bypass check valve 19 opens and the first nozzle 14a is bypassed. Consequently, the first piston chamber 5 is pressurized. Any excess pressure generated by the pump 3 can be relieved via the first return line 33 and the first pressure relief valve 34. The cylinder piston 7 moves in the direction of the second piston chamber 6 and forces hydraulic fluid out of the second piston chamber 6 into the second line arrangement 9. At the same time, the desired steering movement of the boat drive 101 is effected by the movement of the cylinder piston 7.

[0040] The second check valve 25 is closed so that the hydraulic fluid flows via the second nozzle 15a in the direction of the tank 4. The second nozzle 15a limits the volume flow to a maximum volume flow that is independent of a possible external force F.sub.ext. Since the second check valve 11 is hydraulically opened, the hydraulic fluid can flow to the pump 3 or to the tank 4. The pump 3 can draw in hydraulic fluid via tank 4 and selector valve 26.

[0041] Accordingly, when the second piston chamber 6 is pressurized, the hydraulic fluid forced from the first piston chamber 5 into the first line arrangement 8 flows via the first nozzle 14a in the direction of the tank 4, whereby the volume flow is also limited to a maximum value here. Overall, in both steering directions of the boat drive 101, the volume flow is thus limited to a maximum and then constant volume flow and a pressure drop in the line arrangement 8, 9 pressurized by the pump 3 is avoided. In this way, it can be ensured that the first check valve 10 or the second check valve 11 are reliably opened and that the boat 100 can be steered precisely even with an external force F.sub.ext acting on the boat drive 101.

[0042] FIG. 4 shows a hydraulic circuit diagram of a second embodiment of a hydraulic steering unit 1b according to the invention. The steering unit 1b differs from the steering unit 1a shown in FIG. 3 in the configuration of the first throttling device 12b and the second throttling device 13b. In the following, only the differences are described for simplicity.

[0043] As shown, the first throttling device 12b has a first hydraulic resistor formed as an adjustable first nozzle 14b. The first nozzle 14b is adjustable in the opening direction and the closing direction. A first control line 16 branches off from the second line arrangement 9 and acts on the first nozzle 14b in the opening direction. In the exemplary embodiment illustrated, the first control line 16 branches off from the second line arrangement 9 downstream of the second check valve 11, as seen in the direction of flow to the second piston chamber 6. A second control line 17 branches off from the first line arrangement 8 between the first piston chamber 5 and the first nozzle 14b and acts on the first nozzle 14b in the closing direction.

[0044] Accordingly, the second throttling device 13b has a second hydraulic resistor formed as an adjustable second nozzle 15b. The second nozzle 15b is also adjustable in the opening direction and the closing direction. A third control line 20 acts on the second nozzle 15b in the opening direction, the third control line 20 branching off from the first line arrangement 8 downstream of the first check valve 10, as viewed in the flow direction towards the first piston chamber 5 in this embodiment. A fourth control line 21 branches off from the second line arrangement 9 between the second piston chamber 6 and the second nozzle 15b and acts on the second nozzle 15b in the closing direction.

[0045] When pressure is applied to the first line arrangement 8, the pressure in the first line arrangement 8 is signaled to the second nozzle 15b in the closing direction via the third control line 20. Provided that the pressure in the second line arrangement 9 corresponds to the pressure in the first line arrangement 8, the second nozzle 15b remains in its preset position, since the pressure in the second line arrangement 9 is signaled in the closing direction to the second nozzle 15b via the fourth control line 21. However, insofar as an additional external force acts on the boat drive 101 in the steering direction, the pressure in the second line arrangement 9 increases. Thus, a higher pressure signal is signaled to the second nozzle 15b in the closing direction via the fourth control line 21, so that the second nozzle 15b throttles the volume flow more strongly overall. In this way, it can be effectively ensured that the second check valve 11 opens reliably and also remains open. Correspondingly, when the second line arrangement 9 is pressurized, it can thus be effectively ensured that the first check valve 10 opens safely and remains open. “Stuttering” of the first check valve 10 or the second check valve 11 is thus prevented.

[0046] FIG. 5 shows a hydraulic circuit diagram of a third embodiment of a hydraulic steering unit 1c according to the invention. The steering unit 1c differs from the steering unit 1b shown in FIG. 4 in the configuration of the first throttling device 12c and the second throttling device 13c. In the following, only the differences are described for simplicity.

[0047] The first throttling device 12c has a first pressure valve 22, a first signal line 29 and a second signal line 30. The first pressure valve 22 is biased in the closing direction via a first biasing element 39. The first signal line 29 branches off from the first line arrangement 8 between the pressure valve 22 and the first piston chamber 5 and acts on the first pressure valve 22 in the opening direction. The second signal line 30 branches off from the first line arrangement 8 downstream of the first pressure valve 22 between the pressure valve 22 and the tank 4 or the first check valve 10 and acts on the first pressure valve 22 in the closing direction. Furthermore, the pressure signaled via the first control line 16 also acts on the first pressure valve 22 in the opening direction.

[0048] Thus, the first throttling device 12c acts like a load holding valve in that the pressure in the first control line 16 and the pressure in the first signal line 29 control the first pressure valve 22 against the force of the first spring device 39 and the pressure in the second signal line 30. As soon as the pressure in the first control line 16 drops due to an externally acting force F.sub.ext , the first pressure valve 22 is closed and thus limits the volume flow to a maximum and constant value.

[0049] In addition, a third hydraulic resistor 37 in the form of a nozzle is disposed in the first control line 16. This prevents the first pressure valve 22 from starting to oscillate.

[0050] The second throttling device 13c is constructed accordingly so that the first throttling device 12c and the second throttling device 13c act in the manner of a double-acting load-holding valve. For this purpose, the second throttling device 13c has a second pressure valve 23, a third signal line 31 and a fourth signal line 32. The third signaling line 31 branches off from the second line arrangement 9 between the second piston chamber 6 and the second pressure valve 23 and, together with the third control line 20, acts in the opening control direction on the second pressure valve 23 against the force of a second biasing element 40. The fourth signaling line 32 branches off from the second line arrangement 9 between the second pressure valve 23 and the tank 4 or the second check valve 11 and, together with the second biasing element 40, acts in the closing control direction on the second pressure valve 23. Furthermore, a fourth hydraulic resistor 38 is arranged in the third control line 20. The operation of the second throttling device 13c thus corresponds to the operation of the first throttling device 12c described above.

[0051] FIG. 6 shows a hydraulic circuit diagram of a hydraulic steering unit 1d according to a fourth embodiment of the invention. The fourth embodiment differs from the third embodiment shown in FIG. 5 only in the configuration and connection of the steering cylinder unit 102.

[0052] As shown, the steering cylinder unit 102 according to the fourth embodiment comprises a first cylinder 102a and a second cylinder 102b, wherein the first cylinder 102a and the second cylinder 102b are mechanically coupled to each other via the cylinder piston unit 107. For this purpose, the cylinder piston unit 107 comprises a first cylinder piston 107a arranged in the first cylinder 102a, which thus defines the first piston chamber 5. Further, the cylinder piston unit 107 comprises a second cylinder piston 107b arranged in the second cylinder 102b, thus defining the second piston chamber 6. The first cylinder piston 107a and the second cylinder piston 107b are mechanically connected via a common piston rod 107c. However, it is also conceivable that the cylinder pistons 107a, 107b are otherwise coupled, for example hydraulically. There may be air between the cylinders 102a, 102b as shown. However, it is also conceivable that a separate fluid circuit is formed between the cylinders 102a, 102b.

[0053] Furthermore, the steering unit 1d comprises a safety valve 41 which, in the open position shown, connects the first line arrangement 8 to the first piston chamber 5 and the second line arrangement 9 to the second piston chamber 6. The safety valve 41 can, for example, be moved manually into a balancing position in which the first line arrangement 8, the second line arrangement 9, the first piston chamber 5 and the second piston chamber 6 are connected to each other. As a result of this direct pressure equalization, the cylinder piston 7 and consequently the boat drive 101 are brought into a floating position.

[0054] Of course, it is also conceivable that the steering cylinder unit 102 and the safety valve 41 are used in the embodiments shown in FIG. 3 and FIG. 4.