Background Of The Invention In conventional inboard power transmissions, particularly for marine vessels, forward and reverse gear selection can be obtained by operating a valve assembly to direct hydraulic fluid to either one of a pair of multi-plate clutches carried on a horizontally or vertically disposed drive shaft. The drive shaft is ordinarily driven by a substantially horizontally disposed input shaft from the engine of the vessel. The input shaft is provided with a bevel gear which engages a pair of bevel gears associated with the multi-plate clutches on the drive shaft. The drive shaft is in turn connected to a propeller shaft.

The above-mentioned arrangement is particularly useful in marine vessels having an inboard mounted motor and having the transmission and propeller drive arranged in a unit which is pivotally attached to the stern of the vessel.

According to a known arrangement, the drive shaft is provided with internal passages for the conveyance of hydraulic fluid to the multi-plate clutches in response to operation of the valve assembly. In this way, either forward or reverse operation of the propeller shaft may be selected. The

valve assembly is disposed adjacent the drive shaft, and the hydraulic fluid is fed into the internal passages of the drive shaft. The conveyed fluid is controlled by the valve assembly, which in turn comprises a manually rotatable member for selectively guiding the fluid to one of the clutches.

Although the above-described known arrangement normally is reliable and effective, it suffers from a disadvantage in that high levels of vibration and noise can be transmitted from the drive and the transmission to other parts of the vessel via a control cable for the transmission; this vibration reduces the comfort of the passengers in the vessel. Another disadvantage of this arrangement is that since the rotatable member can only be connected to one single control unit via a wire, this control unit can only be operated from one location in the vessel.

The present invention provides an improved valve assembly for a marine transmission which does not suffer from the above vibration problem, and is more versatile than known assemblies.

Summarv Of The Invention The present invention provides a valve assembly for the supply of hydraulic/lubricating fluid to a power transmission in a marine vessel, that is controlled by electric signals. The valve assembly includes a valve having a fluid outlet and at least one passage for conveying the fluid to the transmission. It also includes at least one electrically controlled valve element, communicating with the passage, for controlling the supply of the fluid to the transmission.

The invention further provides a method of operating a power transmission. The transmission has a valve assembly having at least one passage for conveying fluid. In the inventive method, the passage is opened or closed by an electrically controlled valve element

communicating with the passage. Fluid is then supplied to the transmission through the passage when the passage is open to make the transmission operational.

Brief Description Of The Drawings The invention will be described in the following in greater detail by way of example only and with reference to the attached drawings, in which: Figure 1 is a partial sectional view through a power transmission incorporating a valve assembly according to the present invention; Figure 2 is a sectional view through a valve assembly according to the present invention; Figure 3a illustrates, on a larger scale, a valve element to be used in the present invention, in a first position; Figure 3b illustrates the valve element according to Figure 3a, but in a second position; Figure 4 is a partial view of a valve assembly illustrating an alternative embodiment of the invention; Figure 5 is a sectional view through the valve assembly according to an alternative embodiment of the present invention; and Figure 6 illustrates an alternative embodiment of the valve assembly of Figure 2.

Detailed Description Of Preferred Embodiments The invention includes a transmission having an electrically controlled valve element. Supplying or withholding the fluid by the valve element to the transmission determines the operational state of the

transmission. The valve element is preferably of the piston-solenoid type.

Preferably, the valve assembly has a first passage for conveying the fluid to the transmission to select a first predetermined gear and a second passage for conveying the fluid to the transmission to select a second predetermined gear. Each passage is provided with its own electrically controlled valve element, in communication therewith, for controlling the supply of the fluid. The valve elements may be provided with openings defining a vent passage, respectively, for venting the fluid to a fluid reservoir when the valve element is in a closed position and is not supplying fluid to the transmission.

In operation, the valve assembly may be provided with three positions. In the first position, the first valve element supplies the fluid via the first passage and thus selects the first gear (e.g., forward), while the second valve element vents fluid to the fluid reservoir, thus preventing selection of the second gear at the same time. Similarly, in the second position, the second valve element supplies the fluid via the second passage and thus selects the second gear (e.g., reverse), while the first valve element vents fluid to the fluid reservoir, thus preventing selection of the second gear at the same time. A third operational position may be provided, in which the first valve element closes the first passage and the second valve element closes the second passage, thereby selecting a neutral condition of the transmission.

The invention also includes a method of operating a power transmission of a marine vessel by means of an electrically controlled valve element or elements communicating with and opening/closing the above- mentioned passages. The advantage to using electrically controlled valve elements is that no heavy control cable is required from the transmission to the controller, as was in the prior configuration. Thus, vibration from the

transmission will not be transmitted to the passenger area, and a smoother ride will be insured. Further, since the valves are controlled electrically, multiple control units may be easily and inexpensively provided around the vessel, thereby facilitating the control of the vessel.

As illustrated in Figure 1, the present invention includes an inboard power transmission arrangement for a marine vessel provided with a valve assembly 1. In this arrangement, forward and reverse gear selection is obtained by operating the valve assembly 1 to direct hydraulic fluid to either one of a pair of multi-plate clutches 2, 3 carried on a substantially vertical drive shaft 4. The drive shaft 4 is driven by a substantially horizontally disposed input shaft 5 extending from the engine (not shown) of the vessel. The input shaft 5 is provided with a bevel gear 6 which in turn engages a pair of further bevel gears 7, 8 associated with the pair of multi-plate clutches, 2, 3 on the drive shaft 4. The drive shaft 4 is connected at its lower end with an output shaft (not shown) which is intended to drive a propeller in a known manner.

The drive shaft 4 is provided with three internal passages 9, 10, 11 for the conveyance of hydraulic fluid to the pair of multi-plate clutches 2,3 in response to operation of the valve assembly 1, and for the conveyance of a lubricating fluid to the clutches 2, 3. The internal passages 9, 10, 11 will be described in greater detail below.

In the power transmission arrangement illustrated in Figures 1 and 2, the valve assembly 1 is arranged as a combined bearing and fluid supply device. Using the same reference numerals for like components, the valve assembly 1 is advantageously located between the pair of multi-plate clutches 2, 3. Although it is preferred to make use of multi-plate clutches, the invention may also be practiced using clutch mechanisms other than multi-plate clutches, for example single plate clutches.

As is most clearly illustrated in Figure 2, the valve assembly 1 according to the invention comprises a generally cylindrical housing 12 having a circular opening extending therethrough, with the circular opening being delimited by an inner surface 13 of the housing 12. The housing 12 is adapted to be press fitted into a support element 14, with the support element 14 housing the valve assembly 1. The inner surface 13 of the housing 12 is provided with at least one first circumferential channel 15 which accommodates bearings 16 such as roller bearings, ball bearings, taper bearings, or plain bearings. As shown in Figures 1 and 2, the housing 12 preferably accommodates a pair of roller bearings 16 which are axially spaced along the drive shaft 4 and adapted to support the drive shaft 4 passing through the circular opening in the housing 12.

Furthermore, the housing 12 comprises a first bore 17 extending radially from a second circumferential channel 18 in the inner surface 13 to a location on an outer surface 19. Fluid is conveyed from valve assembly 1 to first bore 17, on to second circumferential channel 18, and then to first hole 20 (the hole being disposed in drive shaft 4). First hole 20 conveys the fluid to first internal passage 9 in drive shaft 4 and, the first internal passage 9 communicates with the upper multi-plate clutch 2.

The housing 12 further comprises a second bore 21 extending radially from the inner surface 13 to a location on the outer surface 19. The second bore 21 preferably communicates with a third circumferential channel 22, preferably disposed between bearings 16 in the housing 12 is conveyed from second bare 21 to third circumferential channel 22, and then to second hole 23 (the hole being disposed in drive shaft 4). Second hole 23 conveys the fluid to third internal passage 11, which supplies fluid to both clutches 2 and 3 for lubrication. Simultaneously, by locating the third circumferential channel 22 between the axially spaced bearings 16,

lubricating fluid contacts the bearings, and lubrication of the bearings is ensured.

The housing 12 preferably comprises a third bore 24 extending radially from a fourth circumferential channel 25 in the housing 12. Fluid is conveyed from third bore 24 to fourth circumferential change 25, and then on to third hole 26 (the hole being disposed in drive shaft 4). Third hole 26 conveys the fluid to second internal passage 10.

First internal passage 9 communicates with upper multi-plate clutch 2 via a bore 27 in draft shaft 4, whereas second internal passage 10 communicates with lower inulti-plate clutch 3 via another bore 28 in the drive shaft 4. Furthermore, third internal passage 11 communicates with lubricating ducts in the upper and lower clutches 2 and 3 via bores 29 and 30.

Preferably, the second and fourth circumferentially extending channels 18 and 25 are axially separated by the bearing means 16.

In order to ensure that fluid from the valve assembly 1 is reliably conveyed to its intended destinations, the second circumferential channel 18 is located between a first pair of sealing rings 31 accommodated in first circumferential grooves in the inner surface 13. Similarly, the fourth circumferential channel 25 is located between a second pair of sealing rings 32 accommodated in second circumferential grooves in the inner surface 13. Preferably, the sealing rings 31 and 32 are made from sintered bronze having a low-friction coating. The low-friction coating may be TEFLON, for example.

The supply of fluid to the first, second, and third bores 17, 21, and 24 is controlled by the valve assembly 1. More specifically, the valve assembly 1 comprises a generally cylindrical valve member 33 having an internal fluid supply passageway 34 which receives fluid from a pump (not

shown) and thereby functions as a fluid outlet. Depending on the power and torque output of the engine in the vessel to which the transmission arrangement is mounted, the fluid is supplied to the valve assembly 1 at a pressure which is preferably approximately 10 to 25 bar.

The generally cylindrical valve member 33 is arranged in a valve housing 35 connected to the housing 12. The valve member 33 is provided with a through bore 36 which functions as a passage for fluid to be conveyed to the housing 12, via a first passageway 37 connecting to the second bore 21. The valve member 33 also functions as a passage for fluid to be conveyed to a rear fluid chamber 38, via a second passageway 39.

The rear fluid chamber 38 can be connected to the first bore 17 via an upper valve chamber 40 and a third passageway 41 in a manner which will be described below. This connection can be opened by means of a first valve element 42, which according to this embodiment comprises a first electrically operable solenoid device 43.

The first valve element 42 is shown separately in Figures 3a and 3b.

As is shown in Figure 3a, the valve element 42 comprises a first, generally cylindrical portion 44 which is provided with first and second sets of holes 45 and 46 axially spaced from each other. The valve element 42 also comprises a second generally cylindrical portion 47 having a diameter which is larger than that of the first cylindrical portion 44. Between the sets of holes 45 and 46 is disposed a circumferentially extending partition and sealing element 48.

An essentially cylindrical piston 49 is arranged inside the first cylindrical portion 44 in a manner so as to be slidable between two positions in which it covers either the first set of holes 45 or the second set of holes 46. Piston element 49 is connected to a plunger 50 which forms part of solenoid device 43 and which is adapted to be forced out of an

armature 51 of solenoid 43 when electric power is supplied via an electrical connection 52. Solenoid 43 also comprises a spring element 53 which urges plunger 50 in a direction away from the armature 51, i.e., the leftwards direction in Figure 3a. Solenoid 43 can be a conventional solenoid, the operation of which is known, and is therefore not described here.

Figure 3a illustrates the piston 49 covering the second set of holes 46, indicating that no passage of any fluid is possible through the second set of holes 46 towards the inside of the piston 49. This is the position which the piston 49 adopts when no electric power is supplied to the solenoid 43, i.e., when the spring 53 urges the piston 49 to its leftmost position. In this condition a transport of fluid is instead obtained via the first set of holes 45 and via a third set of holes 74 arranged along the periphery of the piston 49. In this manner, a transport of fluid to the inside of the piston 49 is obtained.

Figure 3b illustrates the position of the piston element 49 when electric power is applied to the solenoid 43. In this condition, the plunger 50 is forced against the action of the spring 53 in the rightwards direction to a position in which the piston element 49 covers the first set of holes 45.

This position corresponds to a condition in which no passage of fluid is possible via the first set of holes 45. On the other hand, in the position of the piston element 49 shown in Figure 3b, the second set of holes 46 are open for passage of fluid. More specifically, fluid may pass via the second set of holes 46 and the third set of holes 74 to the inside of the piston element 49.

Furthermore, as is apparent from Figures 3a and 3b, the piston element 49 is provided with a circumferentially extending recess 75, which provides a passage for fluid from either one of the first or second sets of holes 45, 46, depending on which position the piston element 49 adopts.

Since the recess 75 also extends in the axial direction, the stroke of the piston element 49 can be made relatively short.

Returning to Figure 2, it will be apparent that the valve assembly 1 is also provided with a second valve element 54 and a second electrically operable solenoid device 55. The function of these elements are the same as that described above with reference to Figures 3a and 3b. A control unit (not shown) controls the solenoid devices 43 and 55 via electrical connections 52 and 56. The second valve element 54 is provided with holes 57 and 58, having a function which corresponds to that of holes 45 and 46 described above. It should be noted that although Figure 2 only shows one each of the holes 45, 46, 57, 58, these holes may also be in the form of four sets of holes, corresponding to that shown in Figures 3a and 3b. The operation of the control unit for controlling the solenoid devices will be described in greater detail below.

The valve assembly 1 according to the embodiment shown in Figure 2 is provided with a so-called "take me home" function. This is an important safety feature of the invention which assures that, when no voltage is applied to the solenoids 43, 55, the power transmission is a default function selects the forward gear of the transmission. Such a situation may occur as a result of a power failure when the vessel is at sea.

Accordingly, with reference to Figure 2, when no voltage is supplied to either one of the solenoids 43, 55, hydraulic fluid will be supplied from the internal fluid supply passageway 34, via the rear fluid chamber 38 and into a fourth passageway 59. Since the piston element (not shown) of the second solenoid 55 is in its normal position (i.e., a position corresponding to the position of the first solenoid 43 shown in Figure 3a), hole 57 will be open for passage of fluid. Thus, the fluid will be conveyed through hole 57, on to fifth passageway 60, and into the third bore 24. Thus, the fluid

will be conveyed to the second internal passage 10 which cooperates with the lower multi-plate clutch 3, so that the forward gear is selected.

In this mode of operation, fluid from the fluid chamber 38 will also be conveyed into the upper valve chamber 40 via a sixth passageway 61.

However, the fluid will not be conveyed any further, since the second set of holes 46 of the first valve element 42 blocked (cf. Figure 3a).

Furthermore, hydraulic fluid present in the third passageway 41 will be conveyed via the first set of holes 45 (which is open since the solenoid 52 is not energized) to a first vent passage 62. The fluid is directed via first vent passage 62 to an oil reservoir (not shown).

In a second mode of operation, both the solenoids are energized by means of the control unit. This means that the second set of holes 46 of the first valve element 42 is open for passage of fluid (cf. Figure 3b).

Consequently, fluid will be conveyed from fluid chamber 38, via sixth passageway 61, holes 46, and third passageway 41, to first bore 17. This means that fluid will be conveyed to the first internal passage 9 which cooperates with the upper multi-plate clutch 2, thereby selecting the reverse gear. In this mode of operation , no fluid will pass through the first set of holes 57 of the second valve element 54. Furthermore, in this mode of operation fluid which is present in the fifth passageway 60 is conveyed through holes 58 (which are now open) to a second vent passage 63. The fluid is directed via the second vent passage 63 to an oil reservoir (not shown).

In a third mode of operation, the second solenoid 54 is energized but not the first solenoid 43. In this mode, no fluid in the fluid chamber 38 may pass through either one of the first of holes 57 of the second valve element 54 or the second set of holes 46 of the first valve element 42. This means that a neutral condition is selected in which neither of the clutches 2,

3, (cf. Figure 1) will be activated. This implies that any rotation of the input shaft 5 will not be transferred to the drive shaft 4.

According to a further embodiment of the valve assembly 1 according to the invention which is shown in Figure 4, the valve assembly 1 can also be operated so as to provide a neutral condition of the transmission in the case where no power is supplied to either one of the solenoids 43, 55. According to this embodiment, an alternative fourth passageway 59a is arranged so as to provide a connection from the fluid chamber 38 to the fifty passageway 60, via the second set of holes 58 of the second valve element. Accordingly, the neutral condition is selected when no power is supplied, which can be desirable in certain situations.

Furthermore, forward gear is selected when only the second solenoid 55 is energized, whereas reverse gear is selected when only the first solenoid 43 is energized.

A further embodiment of the invention is shown in Figure 5. Using the same reference numerals for like components, the valve assembly 64 according to this embodiment is not intended to be operated by means of any solenoid devices, but instead is manually controllable. To this end, a rotatable valve member 65 is arranged in a valve housing 35 connected to the housing 12. The valve member 65 is provided with a through bore 66 which functions as a passage for fluid from a fluid pump (now shown) to be conveyed to the housing 12.

The valve member 65 is intended to be manually rotated between three different positions, one of which is illustrated in Figure 5. In this position the forward gear of the transmission is selected, in the following manner. Hydraulic fluid is supplied via the internal fluid supply passage 66 and a first valve member bore 67 to the fifth passageway 60 and further to the third bore 24. In this manner, the fluid will be conveyed to the

second internal passage 10 which cooperates with the lower multi-plate clutch 3, so that the forward gear is selected.

Simultaneously, fluid being present in the third passageway 41 will be conveyed to the rear fluid chamber 38 via a peripherally extending channel 68 in the valve member 65. From the fluid chamber 38 the fluid is conveyed, via the sixth passageway 61 and the first vent passage 62, to an oil reservoir (not shown). The fluid is also conveyed, via the fourth passageway 59 and the second vent passage 63 to said oil reservoir. To this end, the upper valve chamber 40, through which the fluid is conveyed, is plugged by means of a first blocking element 69 which is essentially of the same shape as the first valve element 42 as described above, and can be screwed into the upper valve chamber 40. The left and right ends of the blocking element 69 do not allow any passage of fluid. In a similar manner, a lower valve chamber 70 is plugged by means of a second blocking element 71.

In order to engage reverse gear, the valve member 65 is rotated clockwise approximately 60"-to a position in which a second valve member bore 72 is brought into communication with the third passageway 41. In this position of the valve member 65 fluid is conducted from the internal fluid supply passage 66 to the first bore 17. In this manner, fluid will be conveyed to the first internal passage 9 which cooperates with the upper multi-plate clutch 2, thereby selecting the reverse gear. Simultaneously, fluid present in the fifth passageway 60 will be conveyed via the channel 68 in the valve member 65 to the fluid chamber 38, and further on to the oil reservoir in a manner similar to that described above.

Furthermore, when it is desired to select the neutral condition of the transmission, the valve member 65 is rotated to a position in which neither of bores 67 and 72 is connected to either one of the fifth passageway 60 and

the third passageway 41, respectively. Thereby, neither of the clutches 2, 3 will be activated.

Regardless of the position of the valve member 65, hydraulic fluid is constantly conveyed to the second bore 21 via peripheral channel 73 which extends peripherally along a section of the valve member 65. This means that fluid is always supplied to the third internal passage 11. This fluid is used to lubricate the clutches 2, 3 and to lubricate the bearings 16.

In should be noted that a manual valve assembly according to the embodiment shown in Figure 5 can be used independently of that illustrated in the embodiment shown in Figures 1-4. However, a person who is using a power transmission provided with the manual valve assembly (cf. Figure 5) can with little effort and cost rearrange the manual valve assembly and change it to an electrically controllable one. This can be done simply by replacing the rotatable valve member 65 with the fixed valve member denoted by 33 in Figure 2 and by adding solenoids 43 and 55.

An alternative embodiment of the invention is illustrated as valve assembly 80 in Figure 6 and more clearly indicates the location of holes 20 and 27, 26 and 28, and 23 and 29 in internal passages 9, 10 and 11, respectively. Additionally, as shown, the internal passage 10 can be longer or shorter than internal passage 11.

The invention is not restricted to the embodiments described above and shown in the drawings, but may be varied within the scope of the appended claims. For example, the control of the solenoids 52, 56 (Figure 2) can be carried out from more than one location in a vessel, simply by adding several control units which are connected to solenoids 52, 56. Also, it should be noted that the four sets of holes 45, 46, 57, 58 as described may also comprise one or more holes.