Hydraulic piping structure for a backhoe

Abstract: A hydraulic piping structure for controlling a boom assembly supported through a swing bracket (3) by a swivel deck (2) of a backhoe. The piping structure includes a plurality of hydraulic hoses (19-22) for supplying oil from a pressure source mounted on the swivel deck to hydraulic cylinders for controlling a boom and other components of the boom assembly. These hoses (H) are arranged parallel on an upper face of the boom, with hoses connected to a boom cylinder being curved on a vertical plane. The parallel hoses extend to the swivel deck through an interior space of the swing bracket and are fixed in position by a clamp mechanism therein. On the swivel deck, these hoses are separated into two batches and fixed in position by further clamp mechanisms (C2, C3), respectively.

Description: The present invention relates to a hydraulic piping structure for a backhoe according to the preamble of claim 1. Hydraulic piping structures for supplying pressure oil to cylinders for controlling the boom, arm and bucket of a backhoe are known. JP-A-61-80852 discloses a hydraulic piping structure according to the preamble of claim 1. A similar piping structure is disclosed in JP-A-63-76050. These piping structures include hydraulic hoses extending in an upwardly curved form from a joint disposed on a surface of a swivel deck at a position laterally displaced from a swing bracket, to a terminal mounted on an upper face of a proximal end portion of the boom. Hydraulic hoses for controlling the boom extend in the upwardly curved form from the boom cylinder to be directly connected to the terminal on the swivel deck. In the known structure noted above, the joint mounted on the swivel deck is laterally displaced from the swing bracket, which requires the curved portions of the hydraulic hoses to have additional slack lengths to accommodate sideways swings of the boom as well. Compared with the case where the joint is disposed directly rearwardly of the swing bracket, the hydraulic hoses have longer and higher curved portions. Such hoses could obstruct the driver's filed of view, making it difficult for the driver to carry out a required operation. From US-A-3 120 897 a pressure oil terminal (mainfold block 63) connected to the pressure oil relay station (i.e. the control valve block) by fixed oil lines (see column 4, line 12) and a second group of hydraulic hoses (H1-H8) are known. From FR-A2 323 085 it is known for hydraulic hoses (C) to extend through an interior space of the swing bracket (22); wherein groups of hoses are fixed in position inside said swing bracket (22) by a clamp mechanism (72). None of these references discloses a system to lead the hydraulic hoses in vertical direction through the swing bracket and clamp them by a clamp mechanism inside of the interior space of the swing bracket to avoid obstruction of the driver's field of view. An object of the present invention is to improve the hydraulic piping structure for a backhoe of the type noted at the outset hereof, and to eliminate the disadvantage of the prior art. A hydraulic piping structure according to the present invention may, for example, comprise a pressure oil relaying section disposed in a connection region between the boom and swing bracket, a first group of hydraulic hoses curved on a substantially vertical plane and interconnecting the boom cylinder and pressure oil relaying section, a pressure oil terminal disposed on an upper surface of the boom, fixed oil lines interconnecting the pressure oil relaying section and pressure oil terminal, a second group of hydraulic hoses interconnecting the pressure source and pressure oil terminal, and a third group of hydraulic hoses interconnecting the pressure source and control cylinder. The second and third groups of hydraulic hoses extend to a main backhoe body through a interior space consisting of a space and sideways elongated rectangular communicating space of the swing bracket. To fulfill the above-mentioned object, according to the present invention, the characterising features of claim 1 are used. With the above construction, the first group of hydraulic hoses for supplying oil to the boom cylinder includes curved portions having reduced lengths between the boom and boom cylinder. These hoses may be arranged on the upper surface of the boom together with the second group of hydraulic hoses that supplies oil to the arm cylinder and bucket cylinder. Thus, all of the hydraulic hoses extend parallel to one another through the interior space of the swing bracket to the swivel deck. The hydraulic hoses are fixed in position inside the swing bracket. Thus, the hoses are prevented from making a frictional contact with the swing bracket due to pivotal movement of the boom. The second and third groups of hoses are fixed in position on the swivel deck as laterally separated from each other. This arrangement allows the two groups of hoses to bend and become displaced without mutual interference, despite a difference therebetween in the rate of bending relative to sideways swinging movement of the boom. Thus, the hydraulic hoses have reduced slack lengths adjacent the swing bracket for accommodating both vertical and sideways oscillations of the boom. As a result, the slack lengths as a whole are reduced as compared with those in the prior art, which substantially reduces the bending height of the hydraulic hoses above the swing bracket to minimize the possibility of obstructing the driver's field of view during an operation. The curved portions of the hoses connected to the boom cylinder which now have reduced lengths do not obstruct the driver's field of view either. In the prior art, the hydraulic hoses have been curved upwardly over extensive lengths adjacent the swing bracket, and that in an oblique way. Thus, there has been room for improvement in outward appearance too. According to the present invention, outward appearance is also improved since the hydraulic hoses are arranged parallel to one another and extend directly rearwardly of the boom in an orderly way with a small upward curve and with only minor portions thereof exposed outwardly of the vehicle. Normally, the boom cylinder is more powerful and requires thicker hydraulic hoses than the arm cylinder and bucket cylinder. As a result, horizontal swings of the boom cause the second and third groups of hoses to bend to different degrees on the swivel deck. However, since these groups of hoses are fixed separately from each other, the hoses are free from the damage due to mutual interference. In a preferred embodiment of the invention, the second and third groups of hydraulic hoses are curved on a substantially horizontal plane on the swivel deck to absorb movement of the hydraulic hoses due to horizontal pivoting movement of the boom. The second and third groups of hydraulic hoses may be curved to bulge toward the side of a longitudinal centerline of the backhoe where the boom has a smaller maximum horizontal swing angle. This construction allows horizontal movement of the second and third groups of hoses to be absorbed in a rational way when the boom swings horizontally. The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention, as illustrated in the accompanying drawings. The drawings show a hydraulic piping structure for a backhoe according to the present invention, in which:- Fig. 1 is a side elevation of the backhoe, Fig. 2 is a rear perspective view of a hood, Fig. 3 is a side view, partly in section, of a principal portion of the piping structure, Fig. 4 is a plan view of the principal portion, Fig. 5 is a perspective view of the principal portion, Fig. 6 is a rear view, partly in section, of a guard mechanism, Fig. 7 is a plan view of a clamp mechanism mounted in a swing bracket, and Fig. 8 is a rear view, partly in section, of clamp mechanisms mounted on a swivel deck. DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described hereinafter with reference to the drawings. Referring to Fig. 1, a backhoe vehicle comprises a crawler running device 1, and a swivel deck 2 mounted on the crawler running device 1. The swivel deck 2 carries a boom supporting swing bracket 3 swingable on a vertical axis X1 by a hydraulic cylinder 4. A boom 5 is attached to the swing bracket 3 to be vertically pivotable by a hydraulic cylinder 6. The boom 5 carries an arm 7 vertically pivotable by a hydraulic cylinder 8. The arm 7 carries a bucket 9 vertically pivotable by a hydraulic cylinder 10. The boom 5 includes a service port 11 at a distal end thereof to take out hydraulic power for driving a hydraulic implement such as a hand breaker (not shown). The swivel deck 2 includes a hood 12 mounted on a rear position thereof and housing an engine E. As shown in Fig. 2, thy hood 12 includes a hood cover 13 pivotable on a horizontal axis X2 between an open position and a closed position. The hood 12 further includes an approximately U-shaped protector 14 disposed at an upper rear position to be vertically pivotable on a horizontal axis X3 for protecting the cover 13. Thus the cover 13 may be opened after swinging the protector 14 upwardly. The boom cylinder 6, arm cylinder 8 and bucket cylinder 10 are connected to the swivel deck 2 through hydraulic piping. As shown in Figs. 3 through 5, this piping structure includes a first group of hydraulic hoses 16 curved along a plane of vertical pivotal movement of the boom 5 and connecting the boom cylinder 6 to pressure oil relays 15 disposed adjacent a position of the boom 5 connected to the swing bracket 3. The relays 15 are connected through fixed pipes 18 to pressure oil terminals 17 mounted on an upper surface of the boom 5. Further, a number of hydraulic hoses H are arranged parallel to one another on the upper surface of the boom 5. These hoses H include a second group of hydraulic hoses 19 connected to the terminals 17 for supplying oil to the boom cylinder 6, a third group of hydraulic hoses 20 and 21 respectively for supplying oil to the bucket cylinder 10 and arm cylinder 8, and a fourth group of hydraulic hoses 22 for supplying oil to the service port 11. The parallel hydraulic hoses H extend to the swivel deck 2 through an interior space 23 of the swing bracket 3. The swing bracket 3 includes a clamp mechanism C1 mounted therein for fixing the hydraulic hoses H in position inside the swing bracket 3. The hydraulic hoses H, as they extend from the bracket 3 to the swivel deck 2, are divided into two batches, one of which includes the third group of hydraulic hoses 20 and 21 that supplies oil to the bucket cylinder and arm cylinder, and the other includes the second group of hydraulic hoses 19 that supplies oil to the boom cylinder and the fourth group of hydraulic hoses 22 that supplies oil to the service port. The two batches are laterally spaced apart from each other and fixed to the swivel deck 2 by clamp mechanisms C2 and C3, respectively. As shown in Fig. 3, the swing bracket 3 is connected to the swivel deck 2 through two, upper and lower, pivotal connections 26 and 27. These connections 26 and 27 are aligned on the vertical axis X1 by separate pins (not shown) so as to define a space 23a therebetween. A sideways elongate rectangular communicating section 23b is formed between the upper connection 26 and a boom support portion 3a. The space 23a and communicating section 23b together define the interior space 23 of the swing bracket 3. The hydraulic hoses H, as they extend from the terminals 17 to the bracket 3, are retained by a guard mechanism G to be parallel to one another at a position adjacent the upper surface of the boom 5. As shown in Fig. 6, the guard mechanism G includes an upper plate 28, a lower plate 29, and rubber cushions 30 mounted between the two plates 28 and 29 for holding the hydraulic hoses H parallel to one another. The two plates 28 and 29 are fixed tight together by bolts and nuts. A guard member 32, which is U-shaped in front view, carrying a roller 33 fitted thereon is secured to the lower plate 29. The roller 33 of the guard mechanism G contacts the upper surface of the boom 5 when the boom 5 pivots upward, thereby keeping the hydraulic hoses H out of contact with the boom 5. The roller 33 is rotatable to lessen contact resistance. A round protective bar 34 extends transversely of the bracket 3 above the communicating section 23b, adjacent the boom support portion and forwardly of the guard mechanism G. The protective bar 34 prevents the hydraulic hoses H from contacting a distal end 5a of the boom 5 when the boom 5 pivots downward. Referring to Fig. 7, the hydraulic hoses H are fixed in position inside the communicating section 23b by the clamp mechanism C1 mounted in the interior space 23 of the bracket 3. The clamp mechanism C1 includes rubber cushions 31 holding the hydraulic hoses H therebetween and relative to the communicating section 23b. The hydraulic hoses H are arranged in the order, from right to left with respect to the forward traveling direction of the vehicle, of the hydraulic hoses 22, 19, 21 and 20 which supply oil to the service port 11, boom cylinder 6, arm cylinder 8 and bucket cylinder 10. The hydraulic hoses 20 and 21 have a small diameter and are in a two-step arrangement in the fore and aft direction. As seen from Fig. 4, the third group of hoses 20 and 21 are arranged in a different curved state to the second and fourth groups of hoses 19 and 22. That is, the third group of hoses 20 and 21 has a smaller radius of curvature than the second and fourth groups of hoses 19 and 22. These hoses are curved to bulge toward the smaller swing angle side of the boom 5, namely rightward. As shown in Fig. 4, the boom 5 has a leftward swing angle A1 larger than a rightward swing angle A2 with respect to a longitudinal centerline of the backhoe vehicle. Consequently, the third group of hoses 20 and 21 is bent to a greater degree. This curving state is convenient since the hoses 20 and 21 of, the third group have a smaller diameter than the hoses 19 and 22 of the second and fourth groups. Referring to Fig. 8, the clamp mechanism C3 includes rubber cushions 35 and retainer plates 36 opposed across a tongue 39 erected on the swivel deck 2. The second group of hoses 19 through which oil flows to and from the boom cylinder is arranged vertically on one side of the tongue 39, while the fourth group of hoses 22 through which oil flows to and from the service port is arranged vertically on the other side, the two groups being held tight by a bolt extending through the rubber cushions 35, retainer plates 36 and tongue 39. The clamp mechanism C3 includes rubber cushions 37 and retainer plates 38 lying horizontally for holding the third group of hoses 20 and 21. The hoses 20 through which oil flows to and from the bucket cylinder are arranged horizontally over the hoses 21 also arranged horizontally through which oil flows to and from the arm cylinder. The third group of hoses 20 and 21 is held tight by a bolt extending through the rubber cushions 37 and retainer plates 38 to the swivel deck 2. In the present invention, as described above, the hydraulic piping for the boom cylinder has a divided piping structure including the relaying hoses 16, relays 15 and fixed pipes 18. This allows the hydraulic piping for the boom cylinder to be arranged parallel to the hydraulic hoses 20, 21 and 22 at the pressure oil terminals 17. The hoses 16 may have a minimal length, thereby to present no obstruction to the driver's field of view.

Claims: A hydraulic piping structure for a backhoe having a boom (5), boom support portion (3a) supported by a swivel deck (2) through a swing bracket (3) to be swingable on a vertical axis (X1) and pivotable on a horizontal axis by a boom cylinder (6), at least one control cylinder mounted on said boom for controlling a bucket (9) and an arm (7), and a hydraulic pressure source mounted in said swivel deck region, said piping structure comprising: a first group of hydraulic hoses (16) connecting said boom cylinder (6) to pressure oil relays (15), second group of hydraulic hoses (19) supplying oil to said boom cylinder (6), a third group of hydraulic hoses (20, 21) supplying oil to a bucket cylinder (10) and an arm cylinder (8) respectively, a forth group of hydraulic hoses (22) supplying oil to a service port (11), characterized in that said swivel deck (2) contains two, upper and lower connections (26, 27) which are aligned on said vertical axis (X1), and pivotally connected to corresponding parts, an upper part and a lower part, of said swing bracket (3) respectively through said vertical axis (X1), a communicating section (23b) is formed between a top surface of said upper part and a top surface of said lower part of said swing bracket (3), a space (23a) is formed between two pivotal connections (26, 27) of said swivel deck (2), said communicating section (23b) and said space (23a) together define an interior space (23) of said swing bracket (3), a rectangular opening is provided on said upper part of said swing bracket (3) in a vicinity of said vertical axis (X1), said opening enables a communication through said upper part in a vertical direction, a plurality of group of hoses (H) consists of said second, said third and said forth group of hoses (19, 20, 21, 22) extending from upper surface of said boom (5) to said swivel deck (2) through said interior space (23) of said swing bracket (3), a portion of said plurality of group of hoses (H) extending through said communicating section (23b) is substantially parallel to said vertical axis (X1), and a portion of said plurality of group of hoses (H) extending through said space (23a) is substantially horizontal to a ground, a clamp mechanism (C1) is mounted in said rectangular opening of said upper part of swing bracket (3), and said clamp mechanism comprises a rubber cushion (31) with laterally aligned vertical holes, in which each hose of said plurality of group hoses (H) is fixed.

Inventors: KOBAYASHI MASAHIKO C O KUBOTA, SUGIYAMA SIRO C O KUBOTA LTD, WADA TAKAFUMI C O KUBOTA LTD, KOBAYASHI, MASAHIKO, SUGIYAMA, SIRO, WADA, TAKAFUMI, KOBAYASHI, MASAHIKO, C/O KUBOTA, LTD.,, SUGIYAMA, SIRO, C/O KUBOTA LTD., WADA, TAKAFUMI, C/O KUBOTA LTD.,
Applicants: KUBOTA KK, KUBOTA CORPORATION
Application year: 1990
Main classification: E02F3
IPC codes: F16L3, E02F3, E02F9