Front window opening and closing mechanism

Abstract

To prevent the front window of a cabin of a construction machine from suddenly falling down with a simple structure. [Solution] The front window opening / closing mechanism comprises a guide rail (31), a shaft (34), a bracket (35), a resistance generating section (36), a first guide member (37) guided by the guide rail (31), and a second guide member (38) provided behind the first guide member (37) and guided by the guide rail (31). The front window (15) is guided by the guide rail (31) from the open position and moves forward together with the bracket (35), thereby rotating downward relative to the bracket (35) via the shaft (34) and moving to the closed position. When moving from the open position to the closed position, the resistance generating section (36) generates resistance to the rotation of the shaft (34), and this resistance causes the bracket (35) to move upward, pressing the second guide member (38) against the guide rail (31) from below.

Description

[Technical Field]

[0001] The present invention relates to a front window opening and closing mechanism for a cabin of a construction machine. [Background technology]

[0002] Conventionally, there are known construction machine cabins in which a front window provided on the front of the cabin can be moved between a closed position that blocks the front opening of the cabin and an open position that is moved toward the ceiling of the cabin (see, for example, Patent Documents 1 and 2). In Patent Documents 1 and 2, a drive device that opens and closes the front window using the driving force of a motor is provided on the ceiling side, making it possible to open and close the front window automatically. The front window of a cabin has a large area and is heavy, so it is necessary to prevent the front window from suddenly falling. In Patent Document 1, when the front window is moved from the open position to the closed position, the resistance of the motor via a reducer acts on the front window, preventing the front window from suddenly falling. In Patent Document 2, a fall prevention device having a pulley, a wire connected to the front window, and a spiral spring is disposed inside the cabin, and the biasing force of the spiral spring applies an upward force to the front window, preventing the front window from suddenly falling. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-93511 [Patent Document 2] Japanese Patent Application Publication No. 9-177132 Summary of the Invention [Problem to be solved by the invention]

[0004] However, as in the above-mentioned conventional technology, if a drive unit equipped with a motor is installed on the ceiling side or a relatively large dedicated fall prevention device is installed inside the cabin, the space inside the cabin becomes narrow and the structure becomes complex.

[0005] In view of the above, an object of the present invention is to prevent the front window of a cabin of a construction machine from suddenly falling with a simple structure, thereby making it possible to secure a large space inside the cabin. [Means for solving the problem]

[0006] The front window opening / closing mechanism is a front window opening / closing mechanism that allows a front window provided at the front of a cabin of a construction machine to be moved between a closed position in which the front window blocks the front opening of the cabin and an open position in which the front window has moved to the ceiling side of the cabin, and includes a guide rail extending in the front-to-rear direction on the ceiling side, a shaft that extends in the left-to-right direction from the rear of the front window when in the open position, a bracket connected to the shaft and rotatable around the shaft, a resistance generating unit that is provided between the shaft and the bracket and generates resistance to the rotation of the shaft relative to the bracket, and a resistance generating unit that is guided by the guide rail and moves the front window. The device comprises a first guide member that guides the movement of the rear of the front window, and a second guide member that is provided on the bracket behind the first guide member and guided by the guide rail, and the front window is guided by the guide rail from the open position and moves forward together with the bracket, rotating downward relative to the bracket via the shaft to move to the closed position, and when moving from the open position to the closed position, the resistance generating unit generates resistance to the rotation of the shaft, and this resistance causes the bracket to move upward and the second guide member to be pressed against the guide rail from below. [Effects of the Invention]

[0007] According to the present invention, the front window of the cabin of a construction machine can be prevented from suddenly falling with a simple structure, and a large space can be secured inside the cabin. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view of a cabin according to an embodiment of the present invention, as viewed from the outside. [Figure 2] FIG. 2 is a perspective view of the cabin as seen from the inside. [Figure 3]FIG. 10 is a perspective view showing a state in which the front window is in the middle of moving from an open position to a closed position. [Figure 4] 3 is an enlarged view showing the portion in FIG. 2 where the rear part of the front window is supported by the right ceiling frame. [Figure 5] 10 is a perspective view showing the window-side bracket, the shaft, the bracket, the resistance generating portion, the first guide member, and the second guide member when the front window is in the open position. FIG. [Figure 6] FIG. 10 is a side view showing the change in angle between the bracket and the window-side bracket when the front window is opened or closed. [Figure 7] FIG. 7 is an enlarged view of the resistance generating portion shown in FIG. 6. [Figure 8] 10 is a perspective view showing the front window opening and closing mechanism when the front window is in the middle of moving from an open position to a closed position. FIG. [Figure 9] FIG. 2 is a perspective view showing the front window opening and closing mechanism when the front window is in a closed position. [Figure 10] 10 is a side view showing the resistance generating portion when the front window moves from the open position to the closed position. FIG. [Figure 11] 10 is a side view showing the resistance generating portion when the front window moves from the closed position to the open position. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a front window opening and closing mechanism according to the present invention will be described with reference to the drawings. Fig. 1 is a perspective view of a cabin 10 according to an embodiment of the present invention as seen from the outside. Fig. 1 shows a schematic shape of the cabin 10. Fig. 2 is a perspective view of the cabin 10 as seen from the inside. Fig. 2 omits some parts of the cabin 10 and shows the inside of the cabin 10 as seen from below. In the following description, for convenience, the right, left, front, rear, top, and bottom directions shown in the drawings will be used.

[0010] The cabin 10 is a cabin of a construction machine. Here, a hydraulic excavator will be used as an example of the construction machine. The construction machine comprises a self-propelled lower traveling body (not shown) and an upper rotating body (not shown) provided on the lower traveling body. The upper rotating body can rotate around a rotation axis extending vertically.

[0011] The upper rotating body includes a rotating body frame (not shown) that rotates around the rotation axis, a cabin 10 supported on the rotating body frame, and an excavation attachment (not shown) supported on the rotating body frame. The excavation attachment includes a bucket, an arm that supports the bucket, etc.

[0012] The cabin 10 is formed in a box shape by a front portion 11 (front face), a rear portion 14a, a top surface 12, a left surface 14b, and a right surface 14c. The space inside the cabin 10 is a cab where an operator sits. In the cab, lever devices for operation and the like are arranged.

[0013] The cabin 10 includes a cabin frame 13 that forms the framework of the cabin 10. The cabin 10 is formed into a box shape by attaching various panels (not shown), doors (not shown), a front window 15 (see FIG. 2), etc. to the cabin frame 13.

[0014] The front window 15 can be moved between an open position where the front window 15 is moved toward the top surface portion 12 that forms the ceiling of the cabin 10, and a closed position where the front window 15 is moved toward the front surface portion 11. In FIG. 2, the front window 15 is shown in the open position. FIG. 3 is a perspective view showing a state in which the front window 15 is in the middle of moving from the open position to the closed position.

[0015] Referring to Figures 2 and 3, the cabin frame 13 comprises a pair of left and right front frames 16 extending in the vertical direction (only the upper end of the left front frame 16 is shown), a front cross member 17 connecting the upper ends of the pair of front frames 16 to the left and right, and a pair of left and right ceiling frames 18 extending rearward from the upper ends of the front frames 16 (the left ceiling frame is not shown). Furthermore, the cabin frame 13 includes a pair of left and right rear frames (not shown) extending downward from the rear ends of the pair of ceiling frames 18, and a rear cross member 19 connecting the rear ends of the pair of ceiling frames 18 to the left and right.

[0016] The top surface portion 12 is formed by attaching a ceiling panel (not shown) that covers a pair of ceiling frames 18 from above to the ceiling frames 18. The front portion 11 of the cabin 10 has a front opening 11a that exposes the inside of the cabin 10 to the front. The front opening 11a is an opening surrounded by a front cross member 17 and left and right front frames 16, and has a rectangular shape that extends vertically.

[0017] The front window 15 includes a frame-shaped window frame 21 and a transparent plate-shaped window body 22 supported by the window frame 21. In detail, the window frame 21 comprises a front frame 21a that supports the front edge of the window body 22 in Figures 2 and 3, a rear frame 21b that supports the rear edge of the window body 22, a left frame 21c that supports the left edge of the window body 22, and a right frame 21d that supports the right edge of the window body 22. The window body 22 is, for example, a glass plate.

[0018] 2, the front window 15 is positioned below the top surface 12 with the window body 22 substantially parallel to the top surface 12. In the open position, the front opening 11a is open forward. 3, the front window 15 moves further forward and downward, and is positioned in the closed position. In the closed position, the front window 15 overlaps the front opening 11a from the inside (rear side) of the cabin 10, closing the front opening 11a.

[0019] Fig. 4 is an enlarged view showing the portion in Fig. 2 where the rear portion of the front window 15 is supported by the right-side ceiling frame 18. In Fig. 4, the front window 15 is in the open position. The cabin 10 is provided with a pair of left and right front window opening and closing mechanisms 30 that enable the front windows 15 to be moved between a closed position and an open position. A pair of front window opening and closing mechanisms 30 are provided on the right side of the cabin frame 13 including the right ceiling frame 18, and on the left side of the cabin frame 13 including the left ceiling frame 18. Since the left and right front window opening and closing mechanisms 30 are configured in the same way, the following description will be given in detail with reference to the right front window opening and closing mechanism 30.

[0020] The front window opening / closing mechanism 30 includes an upper guide rail 31 (guide rail) extending in the front-to-back direction on the top surface 12 side, a front guide rail 32 (Figures 2 and 3) extending in the up-down direction on the front surface 11 side, a window side bracket 33 provided on the front window 15, and a shaft 34 extending outward in the left-to-right direction from the rear of the front window 15 when in the open position shown in Figures 2 and 4.

[0021] The front window opening / closing mechanism 30 also includes a bracket 35 connected to the shaft 34 and rotatable around the shaft 34, and a resistance generating unit 36 ​​provided between the shaft 34 and the bracket 35 to generate resistance to the rotation of the shaft 34 relative to the bracket 35. Furthermore, the front window opening / closing mechanism 30 includes a first guide member 37 that is guided by the upper guide rail 31 to guide the movement of the rear of the front window 15, a second guide member 38 that is provided behind the first guide member 37 and guided by the upper guide rail 31, and a front guide member 39 that is guided by the front guide rail 32 (only the left front guide member 39 is shown in Figures 2 and 3).

[0022] FIG. 5 is a perspective view showing the window-side bracket 33, the shaft 34, the bracket 35, the resistance generating portion 36, the first guide member 37, and the second guide member 38 when the front window 15 is in the open position. 2 to 5, the upper guide rail 31 is provided on the inner surface 18a of the ceiling frame 18 in the left-right direction, and extends linearly from the rear end to the front end of the ceiling frame 18. The upper guide rail 31 is a rail formed in a U-shape in a cross section perpendicular to the longitudinal direction. The upper guide rail 31 includes a plate-shaped base 31a extending vertically in a cross section, a plate-shaped lower rail portion 31b extending inward in the left-right direction from the lower end of the base 31a, and a plate-shaped upper rail portion 31c extending inward in the left-right direction from the upper end of the base 31a, and is open toward the inside in the left-right direction. The base 31a of the upper guide rail 31 is fixed to the inner surface 18a.

[0023] The front guide rail 32 (FIG. 2) is provided on the inner surface of the front frame 16 in the left-right direction, and extends from the upper end to the lower end of the front frame 16. The front guide rail 32 is a rail that is formed in a U-shape in cross section, similar to the upper guide rail 31.

[0024] The window-side bracket 33 includes a plate-shaped mounting portion 33a that is attached to the rear end of the window frame 21, and an arm portion 33b that extends rearward from the rear end of the mounting portion 33a relative to the window frame 21. The window-side bracket 33 is fastened to the window frame 21 by a fastener 40 that is inserted into the mounting portion 33a from below.

[0025] The shaft 34 is cylindrical and extends outward in the left-right direction from the rear end of the arm portion 33b toward the front guide rail 32. The shaft 34 is fixed to the front window 15 via a window-side bracket 33.

[0026] The bracket 35 is a plate-like member extending in the front-rear direction along the upper guide rail 31, and is disposed inside the upper guide rail 31 in the left-right direction. The bracket 35 is connected to the shaft 34 by inserting the shaft 34 into the front end of the bracket 35 from the inside in the left-right direction. The window-side bracket 33 and the bracket 35 are relatively rotatable around the shaft 34 as the center of rotation. The bracket 35 also includes a shaft-shaped second guide member support portion 35a (FIG. 5) that extends outward in the left-right direction from the rear end of the bracket 35.

[0027] The shaft 34 includes a shaft main body 34a that is inserted through the resistance generating portion 36 and the front end of the bracket 35, and a guide member support portion 34b that extends outward in the left-right direction from the tip of the shaft main body 34a. The guide member support portion 34b protrudes outward in the left-right direction from the bracket 35.

[0028] The first guide member 37 is a cylindrical roller that fits onto the outer periphery of the guide member support portion 34b of the shaft 34. The first guide member 37 is rotatable around the guide member support portion 34b. The first guide member 37 is disposed between the lower rail portion 31b and the upper rail portion 31c of the upper guide rail 31, and is movable back and forth along the lower rail portion 31b and the upper rail portion 31c. Further, the first guide member 37 is restricted from moving outward in the left-right direction by the base portion 31a of the upper guide rail 31.

[0029] The second guide member 38 is supported by the bracket 35 via the second guide member support portion 35a. The second guide member 38 is a cylindrical roller that fits onto the outer periphery of the second guide member support portion 35a. The second guide member 38 is rotatable around the second guide member support portion 35a. The second guide member 38 is disposed rearward of the first guide member 37 which is disposed at the front end of the bracket 35 .

[0030] The second guide member 38 is disposed between the lower rail portion 31b and the upper rail portion 31c of the upper guide rail 31, and is movable back and forth along the lower rail portion 31b and the upper rail portion 31c. Further, the second guide member 38 is restricted from moving outward in the left-right direction by the base portion 31a of the upper guide rail 31.

[0031] 3, the front guide member 39 is provided at the front end of the front window 15, at the outer edge in the left-right direction of the front window 15. The front guide member 39 is a roller that can rotate around an axis that extends in the left-right direction. The front guide member 39 is attached to the front guide rail 32 and is movable up and down along the front guide rail 32 .

[0032] FIG. 6 is a side view showing the change in angle between the bracket 35 and the window-side bracket 33 when the front window 15 is opened or closed. When the front window 15 is in the open position as shown in FIGS. 2 and 4, the angle θ between the bracket 35 and the window-side bracket 33 is approximately 180° as shown in the upper part of FIG. Here, since the window-side bracket 33 and the front window 15 rotate together, the angle θ corresponds to the angle between the bracket 35 and the front window 15. As shown in Figure 3, when the front window 15 moves toward the closed position, the window-side bracket 33 rotates downward relative to the bracket 35, as shown in the lower part of Figure 6, and the angle θ between the bracket 35 and the window-side bracket 33 becomes smaller.

[0033] FIG. 7 is an enlarged view of the resistance generating section 36 shown in FIG. 5 to 7, the resistance generating unit 36 ​​includes a rotor 50 fitted onto the outer periphery of the shaft 34 and rotatable relative to the shaft 34, a one-way clutch 51 provided between the rotor 50 and the shaft 34, a case 52 that houses the rotor 50, and a fluid 53 filled between the case 52 and the rotor 50.

[0034] The case 52 includes a case main body 54 attached to the bracket 35, and a cover 55 attached to the case main body 54. The cover 55 is illustrated in Fig. 5, and Figs. 6 and 7 show a state in which the cover 55 has been removed.

[0035] The case main body 54 is fixed to the inner side surface of the bracket 35 in the left-right direction at the front end of the bracket 35. The case main body 54 comprises a case bottom wall portion (not shown) attached to the inner surface of the bracket 35, a peripheral wall portion 54a extending inward in the left-right direction from the case bottom wall portion and surrounding the rotor 50, and a fixing portion 54b extending rearward from the peripheral wall portion 54a. The peripheral wall portion 54a is cylindrical. The space surrounded by the peripheral wall portion 54a is a rotor storage portion 54c that stores the rotor 50. The case main body 54 is fastened to the bracket 35 by a case fastener 54d that is inserted into the fixing portion 54b.

[0036] The cover 55 (FIG. 5) includes a cover portion 55a attached to the peripheral wall portion 54a to cover the rotor storage portion 54c, and a fixing portion 55b extending forward from the cover portion 55a. The cover 55 is fastened to the arm portion 33b of the window-side bracket 33 by a cover fixing portion 55c that is inserted into the fixing portion 55b. The cover 55 is rotatable relative to the case main body 54. When the front window 15 rotates around the shaft 34, the cover 55 rotates integrally with the window-side bracket 33 while maintaining the rotor storage portion 54c covered.

[0037] The shaft 34 is inserted through the cover 55, the rotor storage portion 54c, and a hole (not shown) provided in the bottom wall of the case main body portion 54. The rotor 50 is fitted to the outer periphery of the shaft 34 at a portion located within the rotor housing portion 54c. The outer shape of the rotor 50 is a regular polygon (a regular hexagon in this embodiment) when viewed in the axial direction of the shaft 34. Each vertex 50a of the outer shape of the rotor 50 is chamfered. A gap G1 between the vertex 50a and the inner periphery of the peripheral wall 54a is smaller than a gap G2 between each side 50b of the rotor 50 and the inner periphery of the peripheral wall 54a.

[0038] In Figure 7, the rotation direction R1 of the shaft 34 when the front window 15 moves from the open position to the closed position is shown by an arrow, and the rotation direction R2 of the shaft 34 when the front window 15 moves from the closed position to the open position is shown by an arrow. The one-way clutch 51 transmits the rotation of the shaft 34 to the rotor 50 when the shaft 34 rotates in a rotation direction R1, and causes the shaft 34 to rotate freely relative to the rotor 50 when the shaft 34 rotates in a rotation direction R2 opposite to the rotation direction R1.

[0039] The one-way clutch 51 includes a recess 56 provided on the inner circumferential surface of the rotor 50, an engaging member 57 housed in the recess 56, and a biasing member 58 that biases the engaging member 57 in the circumferential direction of the rotor 50. A plurality of recesses 56 are provided at equal intervals around the circumferential direction of the rotor 50.

[0040] The recess 56 extends long in the circumferential direction of the rotor 50. A slope 56a is provided at the bottom of the end of the recess 56 on the rotation direction R1 side, making the recess 56 shallower as it goes toward the rotation direction R1. The engaging member 57 is a roller that is movable in the circumferential direction of the rotor 50 within the recess 56 while in contact with the outer periphery of the shaft 34 . The biasing member 58 is a coil spring that extends in the circumferential direction of the rotor 50 within the recess 56. The biasing member 58 biases the engaging member 57 toward the rotational direction R1.

[0041] The fluid 53 is oil that fills the gap between the peripheral wall portion 54 a and the outer periphery of the rotor 50 . The resistance generating unit 36 ​​applies resistance to the rotation of the shaft 34 by the resistance generated when the rotor 50 rotates in the fluid 53 .

[0042] Here, the opening and closing operation of the front window 15 will be described. Fig. 8 is a perspective view showing the front window opening and closing mechanism 30 when the front window 15 is in the middle of moving from the open position to the closed position. Fig. 9 is a perspective view showing the front window opening and closing mechanism 30 when the front window 15 is in the closed position. 2 and 4, the front window 15 is in the open position, and is substantially parallel to the top surface 12. In the open position, the bracket 35 is located at the rear end of the upper guide rail 31, and the first guide member 37 and the second guide member 38 are guided by the rear end of the upper guide rail 31.

[0043] The operator moves the front window 15 forward by pulling it from the open position. At this time, the rear end of the front window 15 moves forward as the first guide member 37 and the second guide member 38 are guided by the upper guide rail 31, and the front end of the front window 15 moves downward as the front guide member 39 (FIG. 3) is guided by the front guide rail 32. That is, when the front window 15 moves from the open position to the closed position, it moves forward while changing its angle so that the front window 15 assumes an upright position. When the front window 15 moves forward to a certain extent, the front window 15 moves to the closed position side due to its own weight.

[0044] In detail, as shown in Figure 8, when the front window 15 moves from the open position to the closed position, the front window 15 moves forward while rotating downward together with the window-side bracket 33 around the shaft 34 (Figure 6). On the other hand, the bracket 35 is supported by the upper guide rail 31 via the first guide member 37 and the second guide member 38, and therefore moves forward along the upper guide rail 31. In FIG. 8, the angle θ between the bracket 35 and the window-side bracket 33 is smaller than in the state of FIG.

[0045] Also, as shown in Figure 9, when the front window 15 is moved to the closed position, the first guide member 37 and the second guide member 38 are positioned at the front end of the upper guide rail 31, and the front guide member 39 (Figures 2 and 3) is positioned at the lower end of the front guide rail 32. In FIG. 9, the angle θ between the bracket 35 and the window-side bracket 33 is smaller than in the state of FIG.

[0046] 10 is a side view showing the resistance generating portion 36 when the front window 15 moves from the open position to the closed position. In FIG. 10, the cover 55 is not shown. When the shaft 34 rotates in the rotational direction R1 as the front window 15 moves from the open position to the closed position, the engaging member 57 of the one-way clutch 51 receives a force in the rotational direction R1 via the outer circumferential surface of the shaft 34, and is also pushed in the rotational direction R1 by the biasing member 58. As a result, the engaging member 57 bites into the gap between the inclined surface 56a and the outer circumferential surface of the shaft 34, the one-way clutch 51 enters an engaged state, and the rotation of the shaft 34 is transmitted to the rotor 50.

[0047] When one-way clutch 51 is engaged and rotor 50 rotates integrally with shaft 34 in rotational direction R1, the rotation of rotor 50 is decelerated by the resistance of fluid 53. The resistance of fluid 53 is then transmitted to shaft 34 via rotor 50, decelerating the rotation of shaft 34. As a result, the downward rotation of front window 15 about shaft 34 as its center of rotation is decelerated when moving from the open position to the closed position, preventing front window 15 from suddenly falling.

[0048] Also, referring to Figures 4, 6 and 8, the resistance generated by the resistance generating portion 36 when the front window 15 moves from the open position to the closed position acts on the bracket 35 as a force F that moves the bracket 35 upward. When the bracket 35 receives the force F, the rear of the bracket 35 rises up, using the first guide member 37, which is in contact with the lower rail portion 31b of the upper guide rail 31, as a fulcrum, and the second guide member 38 is pressed against the lower surface of the upper rail portion 31c from below. This increases the friction between the first guide member 37 and the lower rail portion 31b and the friction between the second guide member 38 and the upper rail portion 31c, slowing down the forward movement of the front window 15 toward the closed position, thereby preventing the front window 15 from suddenly falling.

[0049] 11 is a side view showing the resistance generating portion 36 when the front window 15 moves from the closed position to the open position. In FIG. 11, the cover 55 is not shown. The operator moves the front window 15 upward from the closed position (Fig. 9) by pulling the upper part of the front window 15 rearward. At this time, the first guide member 37 and the second guide member 38 of the bracket 35 move rearward while being guided by the upper guide rail 31, and the front guide member 39 (Fig. 3) moves upward while being guided by the front guide rail 32. Accordingly, the front window 15 rotates upward relative to the bracket 35, and the shaft 34 rotates in the rotational direction R2. Accordingly, the angle θ (Fig. 6) increases.

[0050] When the shaft 34 rotates in the rotational direction R2 as the front window 15 moves from the closed position to the open position, the engaging member 57 of the one-way clutch 51 receives a force in the rotational direction R2 via the outer circumferential surface of the shaft 34, and moves in the rotational direction R2 against the biasing force of the biasing member 58. As a result, the engaging member 57 disengages from the inclined surface 56a, the one-way clutch 51 is disengaged, and the shaft 34 rotates freely relative to the rotor 50. Therefore, even if the shaft is rotated in the rotation direction R2, the rotor 50 does not rotate, and the resistance of the fluid 53 does not act on the shaft . In this way, when the front window 15 is moved from the closed position to the open position, no resistance is generated by the resistance generating section 36, so the front window 15 can be easily moved from the closed position to the open position.

[0051] As described above, according to an embodiment to which the present invention is applied, the front window opening and closing mechanism 30 makes it possible to move the front window 15 provided on the front portion 11 of the cabin 10 of a construction machine between a closed position in which the front window 15 blocks the front opening 11a of the cabin 10, and an open position in which the front window 15 has moved toward the top surface 12 of the cabin 10. The front window opening and closing mechanism 30 includes an upper guide rail 31 extending in the front-to-rear direction on the top surface 12 side, a shaft 34 extending in the left-to-right direction from the rear of the front window 15 when in the open position, a bracket 35 connected to the shaft 34 and rotatable about the shaft 34, a resistance generating unit 36 ​​provided between the shaft 34 and the bracket 35 and generating resistance to the rotation of the shaft 34 relative to the bracket 35, a first guide member 37 guided by the upper guide rail 31 to guide movement of the rear portion of the front window 15, and a second guide member 38 provided on the bracket 35 behind the first guide member 37 and guided by the upper guide rail 31. The front window 15 is guided by the upper guide rail 31 from the open position and moves forward together with the bracket 35, causing it to rotate downward relative to the bracket 35 via the shaft 34 and move to the closed position.When moving from the open position to the closed position, the resistance generating unit 36 ​​generates resistance to the rotation of the shaft 34, and this resistance causes the bracket 35 to move upward and the second guide member 38 to be pressed against the upper guide rail 31 from below. With this configuration, when the front window 15 is guided by the upper guide rail 31 from the open position and moves forward together with the bracket 35, and then rotates downward relative to the bracket 35 via the shaft 34 toward the closed position, the resistance generating unit 36 ​​generates resistance to the rotation of the shaft 34, slowing down the downward rotation of the front window 15 and preventing the front window 15 from suddenly falling. Furthermore, when the front window 15 rotates downward toward the closed position, the resistance of the resistance generating unit 36 ​​causes the bracket 35 to move upward and presses the second guide member 38 against the upper guide rail 31 from below, increasing friction between the second guide member 38 and the upper guide rail 31. This friction slows down the movement of the front window 15, which is guided forward by the upper guide rail 31, and prevents the front window 15 from suddenly falling. In this way, with the front window opening / closing mechanism 30, the resistance of the resistance generating unit 36 ​​against the shaft 34 can prevent the front window 15 from suddenly falling, and further, the resistance of the resistance generating unit 36 ​​can be used to press the second guide member 38 against the upper guide rail 31 to prevent the front window 15 from suddenly falling, making it possible to prevent the front window 15 from suddenly falling with a simple structure. This allows for a large space to be secured inside the cabin 10.

[0052] Furthermore, the resistance generated by the resistance generating unit 36 ​​is greater when moving from the open position to the closed position than when moving from the closed position to the open position. With this configuration, when moving from the closed position to the open position, the resistance of resistance generating section 36 is small, so front window 15 can be easily moved from the closed position to the open position. Also, when moving from the open position to the closed position, the resistance of resistance generating section 36 is large, so sudden falling of front window 15 can be effectively prevented.

[0053] Resistance generating unit 36 ​​also includes rotor 50 fitted onto the outer periphery of shaft 34 and rotatable relative to the shaft, one-way clutch 51 provided between rotor 50 and shaft 34, case 52 provided on bracket 35 and accommodating rotor 50, and fluid 53 filled between case 52 and rotor 50. One-way clutch 51 causes rotor 50 to rotate freely relative to shaft 34 when moving from the closed position to the open position, and causes rotor 50 to rotate integrally with shaft 34 when moving from the open position to the closed position. With this configuration, one-way clutch 51 causes rotor 50 to rotate freely relative to shaft 34 when moving from the closed position to the open position, so no resistance is generated by resistance generating unit 36, and front window 15 can be easily moved from the closed position to the open position. Furthermore, one-way clutch 51 causes rotor 50 to rotate integrally with shaft 34 when moving from the open position to the closed position, so resistance is generated as rotor 50 rotates through fluid 53, effectively preventing front window 15 from suddenly falling.

[0054] Furthermore, the shaft 34 includes a guide member support portion 34b that extends toward the upper guide rail 31, and the first guide member 37 is supported by the guide member support portion 34b. According to this configuration, by providing the guide member support portion 34b on the shaft 34, the first guide member 37 can be supported by using the shaft 34, and the structure can be simplified.

[0055] Although one embodiment of the present invention has been described above, the present invention is not limited to the specific embodiment, and unless otherwise limited in the above description, various modifications and variations are possible within the spirit and scope of the present invention as defined in the claims. For example, the configurations of the above-described embodiment may be added or deleted as appropriate, and the configurations of one embodiment may be incorporated into other embodiments. Furthermore, the effects of the above-described embodiment are merely examples of the effects resulting from the present invention, and do not mean that the effects of the present invention are limited to the above-described effects. In the above embodiment, the first guide member 37 and the second guide member 38 are rollers that roll within the upper guide rail 31, but the present invention is not limited to this, and the first guide member 37 and the second guide member 38 may also be sliding members that slide within the upper guide rail 31. In the above embodiment, the first guide member 37 is described as being supported by the guide member support portion 34b of the shaft 34, but the present invention is not limited to this. For example, a guide member support shaft may be provided behind the shaft 34 in the bracket 35, and the first guide member 37 may be supported by this guide member support shaft. [Explanation of symbols]

[0056] 10: Cabin 11: Front part (front) 11a: Front opening 12:Top section (ceiling) 15: Front window 30: Front window opening and closing mechanism 31: Upper guide rail (guide rail) 34: Shaft 34b: Guide member support part 35: Bracket 36: Resistance generating section 37: First guide member 38: Second guide member 50: Rotor 51: One-way clutch 52: Case 53: Fluid

Claims

1. A front window opening and closing mechanism that enables a front window provided on the front of a cabin of a construction machine to be moved between a closed position in which the front window closes a front opening of the cabin and an open position in which the front window moves toward the ceiling of the cabin, a guide rail extending in the front-rear direction on the ceiling side; a shaft extending in the left-right direction from the rear of the front window when in the open position; a bracket connected to the shaft and rotatable around the shaft; a resistance generating section provided between the shaft and the bracket and generating resistance to the rotation of the shaft relative to the bracket; a first guide member guided by the guide rail and guiding the movement of the rear of the front window; and a second guide member provided on the bracket behind the first guide member and guided by the guide rail, the front window is guided by the guide rail from the open position and moves forward together with the bracket, thereby rotating downward relative to the bracket via the shaft and moving to the closed position; When moving from the open position to the closed position, the resistance generating unit generates resistance to the rotation of the shaft, and this resistance causes the bracket to move upward and the second guide member to be pressed against the guide rail from below.

2. The front window opening and closing mechanism according to claim 1 , wherein the resistance generated by the resistance generating unit is greater when moving from the open position to the closed position than when moving from the closed position to the open position.

3. the resistance generating unit includes a rotor fitted onto the outer periphery of the shaft and rotatable relative to the shaft, a one-way clutch provided between the rotor and the shaft, a case provided on the bracket and accommodating the rotor, and a fluid filled between the case and the rotor, 2. The front window opening and closing mechanism according to claim 1, wherein the one-way clutch causes the rotor to rotate freely relative to the shaft when moving from the closed position to the open position, and causes the rotor to rotate integrally with the shaft when moving from the open position to the closed position.

4. the shaft includes a guide member support portion extending toward the guide rail, The front window opening and closing mechanism according to claim 1 , wherein the first guide member is supported by the guide member support portion.

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