Work machine

Abstract

To improve comfort of an operator in a cab.SOLUTION: A work machine 100 comprises a cab 10, a lifting cylinder 62 which is a single-rod hydraulic cylinder for raising and lowering the cab 10, and an extendable restraining mechanism RM for restraining movement of the cab 10. Specifically, the work machine 100 is equipped with a cab lifting mechanism 60 that includes a plurality of movable members. An upper end of the lifting cylinder 62 is connected to an upper link 69 which is one of the plurality of movable members. An upper end of the restraining mechanism RM is connected to a lower link 70 which is another one of the plurality of movable members.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to work machines. [Background technology]

[0002] 2. Description of the Related Art Conventionally, there has been known a work machine equipped with a cab lifting mechanism for lifting and lowering a cab (operator's compartment) (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-155997 Summary of the Invention [Problem to be solved by the invention]

[0004] The above-mentioned working machine is configured so that the platform (cab frame) to which the cab is attached can be maintained in a raised state by maintaining the lifting cylinder in an extended state.

[0005] However, with this configuration, the cab may sway in response to external forces such as work reaction forces while the work machine is in operation, which may impair the comfort of the operator inside the cab.

[0006] It is therefore desirable to improve the comfort of the operator within the cab. [Means for solving the problem]

[0007] A work machine according to an embodiment of the present disclosure includes a cab, a lifting cylinder that raises and lowers the cab, and an extendable restraining mechanism that restrains movement of the cab. Effect of the Invention

[0008] The above-described work machine can improve comfort for the operator within the cab. [Brief description of the drawings]

[0009] [Figure 1] 1 is an overall schematic diagram showing a work machine according to an embodiment of the present disclosure; [Diagram 2] FIG. 2 is a perspective view of a cab lifting mechanism mounted on the work machine. [Diagram 3] 2 is a diagram showing an example of the configuration of a hydraulic circuit related to a restraint mechanism mounted on a work machine. FIG. [Figure 4] 13 is a diagram showing the state of the hydraulic circuit when the restraint mechanism is extended. FIG. [Diagram 5] FIG. 13 is a diagram showing the state of the hydraulic circuit when the restraining mechanism is contracted. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is an overall schematic diagram of a work machine 100 according to an embodiment of the present disclosure.

[0011] The work machine 100 has a lower traveling body 1, a rotating mechanism 2, an upper rotating body 3, a boom 4, an arm 5, an end attachment 6, a boom cylinder 7, an arm cylinder 8, an end attachment cylinder 9, a cab 10, and a cab lifting mechanism 60, etc.

[0012] Specifically, an upper rotating body 3 is rotatably mounted on a lower traveling body 1 of the work machine 100 via a rotating mechanism 2. A boom 4 is rotatably connected to the front center of the upper rotating body 3, an arm 5 is rotatably connected to the tip of the boom 4, and an end attachment 6 is rotatably connected to the tip of the arm 5. In the illustrated example, the end attachment 6 is a lifting magnet, but other end attachments such as a grapple or fork grapple may be attached depending on the type of work.

[0013] In addition, a cab 10 serving as a driver's cab is provided on the upper rotating body 3 so as to be movable up and down via a cab lifting mechanism 60. The cab 10 which can be raised and lowered in this manner is also called an "elevator cab" or a "movable high cab." Note that Fig. 1 shows a state in which the cab 10 has been raised to the highest position by the cab lifting mechanism 60. The cab 10 is also disposed to the side (usually the left side) of the boom 4.

[0014] Next, the cab lifting / lowering mechanism 60 will be described in detail with reference to Fig. 2. Fig. 2 is a perspective view of the cab lifting / lowering mechanism 60 of the work machine 100 according to the embodiment of the present disclosure. Specifically, Fig. 2 shows the state of the cab lifting / lowering mechanism 60 when viewed from diagonally forward left. In the illustrated example, the cab lifting / lowering mechanism 60 is disposed on the left side of the rotating frame AF to which the boom 4 is rotatably attached. Note that, for clarity, the cab 10 is omitted from Fig. 2.

[0015] 2, the cab lifting mechanism 60 includes a parallel link mechanism 61 that keeps a platform 64 to which the cab 10 is fixed in a predetermined position (horizontal state), and a lifting cylinder 62 that drives the parallel link mechanism 61 to lift and lower the platform 64 (cab 10). The platform 64 is also called a "cab frame."

[0016] The parallel link mechanism 61 is composed of a support tower 63 erected on the upper rotating body 3, a substantially L-shaped platform 64 supporting the cab 10 from below, and an upper link 69 and a lower link 70 rotatably connected between the support tower 63 and the platform 64. The support tower 63 is also called an "elevator bracket". Specifically, the platform 64 is integrated with the lower part of the cab 10 as shown in FIG. 1. As shown in FIG. 2, the upper end of the upper link 69 is connected to the platform 64 via a first upper end pin 67, and the lower end is connected to the support tower 63 via a first lower end pin 65. The lower link 70 is connected to the platform 64 via a second upper end pin 68, and the lower end is connected to the support tower 63 via a second lower end pin 66. 2, the upper link 69 and the lower link 70 are each integrated so as to form a rectangular frame, i.e., so as to be connected left and right and cannot be separated into left and right halves. However, the upper link 69 and the lower link 70 may each be configured as a left and right pair, i.e., so as to be separable into left and right halves.

[0017] The lifting cylinder 62 is configured to be able to rotate the upper link 69 and the lower link 70 relative to the support tower 63. Specifically, the base end of the lifting cylinder 62 is rotatably supported on the lower part of the support tower 63 via a cylinder pin 71. In addition, the tip end of the rod 62a of the lifting cylinder 62 is connected to a pair of left and right upper links 69 via rod pins 72.

[0018] With this configuration, the cab lifting mechanism 60 is driven to lift by supplying hydraulic oil from the hydraulic pump to the lifting cylinder 62. Specifically, the cab lifting mechanism 60 can move the platform 64 up and down by extending and contracting the lifting cylinder 62, causing the upper link 69 to draw an arc with the first lower end pin 65 as a fulcrum and causing the lower link 70 to draw an arc with the second lower end pin 66 as a fulcrum. Note that the platform 64 moves in the front-rear direction in addition to the up-down direction.

[0019] The suppression mechanism RM is a telescopic mechanism that suppresses the movement of the cab 10. Specifically, the suppression mechanism RM is configured to expand and contract in response to the movement of the cab 10, and to suppress the vibration or rocking of the cab 10 during operation of the work machine 100. The vibration or rocking of the cab 10 includes vibration or rocking in the up-down direction and vibration or rocking in the front-rear direction. The suppression mechanism RM is also configured to suppress the descent speed of the cab 10. The lifting cylinder 62 is configured not to expand and contract basically even when an external force such as a work reaction force acts on the cab 10 and causes the cab 10 to rock, because a fall prevention valve is provided in the oil passage connected to the lifting cylinder 62. Therefore, the lifting cylinder 62 cannot attenuate the rocking of the cab 10 during operation of the work machine 100. The suppression mechanism RM is configured to attenuate such rocking of the cab 10 that cannot be attenuated by the lifting cylinder 62.

[0020] In the illustrated example, the suppression mechanism RM is composed of an auxiliary cylinder 50, which is a single-rod hydraulic cylinder. The auxiliary cylinder 50 includes a left auxiliary cylinder 50L and a right auxiliary cylinder 50R. Specifically, the tip of the rod 50a of the auxiliary cylinder 50 is connected to a pair of left and right lower links 70 via an upper connecting member 51 and an upper rod pin 52. The upper connecting member 51 is a bracket welded to the lower link 70. More specifically, the tip of the rod 50La of the left auxiliary cylinder 50L is pivotally supported by the left lower link 70 via an upper left connecting member 51L and an upper left rod pin 52L, and the tip of the rod 50Ra of the right auxiliary cylinder 50R is pivotally supported by the right lower link 70 (not visible in FIG. 2) via an upper right connecting member 51R (not visible in FIG. 2) and an upper right rod pin 52R (not visible in FIG. 2).

[0021] Further, the base end of the auxiliary cylinder 50 is rotatably supported at the center of the support tower 63 via a lower connecting member 53 and a lower cylinder pin 54. The lower connecting member 53 is a bracket welded to the center of the support tower 63. More specifically, the base end of the left auxiliary cylinder 50L is rotatably supported at the center of the support tower 63 via a lower-left connecting member 53L (not visible in FIG. 2) and a lower-left cylinder pin 54L, and the base end of the right auxiliary cylinder 50R is rotatably supported at the center of the support tower 63 via a lower-right connecting member 53R and a lower-right cylinder pin 54R.

[0022] Next, the movement of the auxiliary cylinder 50, which is an example of the suppression mechanism RM, will be described with reference to Fig. 3. Fig. 3 is a diagram showing an example of the configuration of a hydraulic circuit HT related to the auxiliary cylinder 50. The hydraulic circuit HT includes an oil passage CD, a hydraulic oil source HS, a flow direction restricting unit 41, a flow rate restricting unit 42, and the auxiliary cylinder 50.

[0023] The oil passage CD includes the first oil passage CD1 to the twelfth oil passage CD12. The first oil passage CD1 is an oil passage that connects the hydraulic oil source HS and the first connection point CP1. The second oil passage CD2 is an oil passage that connects the first connection point CP1 and the second connection point CP2. The third oil passage CD3 is one of two oil passages arranged in parallel that connect the second connection point CP2 and the third connection point CP3. The fourth oil passage CD4 is the other of two oil passages arranged in parallel that connect the second connection point CP2 and the third connection point CP3. The fifth oil passage CD5 is an oil passage that connects the third connection point CP3 and the fourth connection point CP4. The sixth oil passage CD6 is an oil passage that connects the fourth connection point CP4 and the head side oil chamber HCL of the left auxiliary cylinder 50L. The head side oil chamber HCL is also called the "rod side oil chamber". The seventh oil passage CD7 is an oil passage connecting the fourth connection point CP4 and the head side oil chamber HCR of the right auxiliary cylinder 50R. The eighth oil passage CD8 is one of two oil passages arranged in parallel connecting the first connection point CP1 and the fifth connection point CP5. The ninth oil passage CD9 is the other of two oil passages arranged in parallel connecting the first connection point CP1 and the fifth connection point CP5. The tenth oil passage CD10 is an oil passage connecting the fifth connection point CP5 and the sixth connection point CP6. The eleventh oil passage CD11 is an oil passage connecting the sixth connection point CP6 and the bottom side oil chamber BCL of the left auxiliary cylinder 50L. The twelfth oil passage CD12 is an oil passage connecting the sixth connection point CP6 and the bottom side oil chamber BCR of the right auxiliary cylinder 50R.

[0024] The hydraulic oil source HS is a hydraulic oil source capable of supplying hydraulic oil. In the illustrated example, the hydraulic oil source HS is a hydraulic oil line provided in an oil cooler. The pressure of the hydraulic oil supplied by the hydraulic oil source HS is relatively low and is significantly lower than the pressure of the hydraulic oil discharged by the hydraulic pump to drive the lift cylinder 62. Therefore, the hydraulic oil source HS may be a hydraulic oil tank, an oil cooler, or the like. In other words, the hydraulic oil in the hydraulic oil source HS does not need to be pressurized when it is supplied to the suppression mechanism RM.

[0025] The flow direction limiting unit 41 is a hydraulic element that allows the flow of hydraulic oil from the hydraulic oil source HS toward the auxiliary cylinder 50 and limits the flow of hydraulic oil from the auxiliary cylinder 50 toward the hydraulic oil source HS. In the illustrated example, the flow direction limiting unit 41 includes a check valve 41H as a first flow direction limiting unit provided in the third oil passage CD3 and a check valve 41B as a second flow direction limiting unit provided in the eighth oil passage CD8. The check valve 41H allows the flow of hydraulic oil from the hydraulic oil source HS toward the head side oil chamber HC of the auxiliary cylinder 50 and limits (blocks) the flow of hydraulic oil from the head side oil chamber HC of the auxiliary cylinder 50 toward the hydraulic oil source HS. The check valve 41B allows the flow of hydraulic oil from the hydraulic oil source HS toward the bottom side oil chamber BC of the auxiliary cylinder 50 and limits (blocks) the flow of hydraulic oil from the bottom side oil chamber BC of the auxiliary cylinder 50 toward the hydraulic oil source HS. The flow direction restricting portion 41 may be a switching valve that opens when the hydraulic oil flows from the hydraulic oil source HS toward the auxiliary cylinder 50 and closes when the hydraulic oil flows from the auxiliary cylinder 50 toward the hydraulic oil source HS. The switching valve may be an electromagnetic switching valve or a hydraulic switching valve.

[0026] The flow rate limiting unit 42 is a hydraulic element that limits the flow rate of the hydraulic oil flowing from the auxiliary cylinder 50 toward the hydraulic oil source HS. In the illustrated example, the flow rate limiting unit 42 includes a fixed throttle valve 42H as a first flow rate limiting unit provided in the fourth oil passage CD4 and a fixed throttle valve 42B as a second flow rate limiting unit provided in the ninth oil passage CD9. The fixed throttle valve 42H limits the flow rate of the hydraulic oil flowing from the head side oil chamber HC of the auxiliary cylinder 50 toward the hydraulic oil source HS. The fixed throttle valve 42B limits the flow rate of the hydraulic oil flowing from the bottom side oil chamber BC of the auxiliary cylinder 50 toward the hydraulic oil source HS. The flow rate limiting unit 42 may be a variable throttle valve or a switching valve whose opening area becomes zero when the hydraulic oil flows from the hydraulic oil source HS toward the auxiliary cylinder 50 and whose opening area becomes large when the hydraulic oil flows from the auxiliary cylinder 50 toward the hydraulic oil source HS. Alternatively, the flow rate limiting unit 42 may be a variable throttle valve or a switching valve whose opening area can be controlled in accordance with the operation of the work machine 100. The variable throttle valve may be an electromagnetic variable throttle valve or a hydraulic variable throttle valve, and the switching valve may be an electromagnetic switching valve or a hydraulic switching valve.

[0027] Next, referring to Fig. 4, the flow of hydraulic oil in the hydraulic circuit HT when the auxiliary cylinder 50 extends will be described. Fig. 4 is a diagram showing the state of the hydraulic circuit HT when the auxiliary cylinder 50 extends, and corresponds to Fig. 3. To make the explanation easier to understand, Fig. 4 shows the oil passage through which the hydraulic oil flows from the auxiliary cylinder 50 toward the hydraulic oil source HS with a thick dotted line, and the oil passage through which the hydraulic oil flows from the hydraulic oil source HS toward the auxiliary cylinder 50 with a thick solid line. Fig. 4 also shows the flow of hydraulic oil with arrows.

[0028] Specifically, as shown by the block arrows, when the auxiliary cylinder 50 expands, the volume of the head side oil chamber HC of the auxiliary cylinder 50 contracts, and the hydraulic oil in the head side oil chamber HC flows out of the head side oil chamber HC. On the other hand, the volume of the bottom side oil chamber BC of the auxiliary cylinder 50 expands, and the hydraulic oil in the oil passage CD flows into the bottom side oil chamber BC.

[0029] The auxiliary cylinder 50 is extended, for example, when the platform 64 to which the cab 10 is fixed moves upward. The upward movement of the platform 64 occurs, for example, when the work machine 100 swings in the front-rear direction or the left-right direction due to a change in the work load on the end attachment 6. Alternatively, the upward movement of the platform 64 occurs, for example, when the work machine 100 swings in the front-rear direction or the left-right direction while the work machine 100 is traveling.

[0030] Specifically, the hydraulic oil of the hydraulic oil source HS passes through the first oil passage CD1, the eighth oil passage CD8, and the tenth oil passage CD10 to reach the sixth connection point CP6, and is then split into two at the sixth connection point CP6. One of the split hydraulic oil flows into the bottom oil chamber BCL of the left auxiliary cylinder 50L through the eleventh oil passage CD11, and the other flows into the bottom oil chamber BCR of the right auxiliary cylinder 50R through the twelfth oil passage CD12. The fixed throttle valve 42B provided in the ninth oil passage CD9 makes the flow resistance of the ninth oil passage CD9 greater than the flow resistance of the eighth oil passage CD8, so that most of the hydraulic oil from the hydraulic oil source HS flows through the eighth oil passage CD8. The check valve 41B provided in the eighth oil passage CD8 does not impede the flow of hydraulic oil from the hydraulic oil source HS toward the auxiliary cylinder 50.

[0031] On the other hand, the hydraulic oil flowing out from the head side oil chamber HCL of the left auxiliary cylinder 50L passes through the sixth oil passage CD6, the fifth oil passage CD5, the fourth oil passage CD4, and the second oil passage CD2 to the first connection point CP1, and merges with the hydraulic oil flowing from the hydraulic oil source HS to the auxiliary cylinder 50 at the first connection point CP1. The hydraulic oil flowing out from the head side oil chamber HCR of the right auxiliary cylinder 50R passes through the seventh oil passage CD7 to the fourth connection point CP4, and merges with the hydraulic oil flowing from the head side oil chamber HCL of the left auxiliary cylinder 50L to the hydraulic oil source HS at the fourth connection point CP4. The check valve 41H provided in the third oil passage CD3 blocks the flow of hydraulic oil from the auxiliary cylinder 50 to the hydraulic oil source HS. Therefore, the hydraulic oil flowing out from the head side oil chamber HC of the auxiliary cylinder 50 flows toward the hydraulic oil source HS through the fourth oil passage CD4, not the third oil passage CD3. Since the fixed throttle valve 42H is provided in the fourth oil passage CD4, the flow resistance of the fourth oil passage CD4 when the hydraulic oil flows from the auxiliary cylinder 50 toward the hydraulic oil source HS is greater than the flow resistance of the third oil passage CD3 when the hydraulic oil flows from the hydraulic oil source HS toward the auxiliary cylinder 50. As a result, the extension speed of the auxiliary cylinder 50 is limited by the fixed throttle valve 42H. Note that, the smaller the opening area of ​​the fixed throttle valve 42H, the greater the limitation on the extension speed of the auxiliary cylinder 50, the greater the movement resistance during extension of the auxiliary cylinder 50, and the slower the extension speed of the auxiliary cylinder 50.

[0032] Next, the flow of hydraulic oil in the hydraulic circuit HT when the auxiliary cylinder 50 contracts will be described with reference to Fig. 5. Fig. 5 is a diagram showing the state of the hydraulic circuit HT when the auxiliary cylinder 50 contracts, and corresponds to Fig. 3. Also, in Fig. 5, for ease of understanding, the oil passage through which the hydraulic oil flows from the auxiliary cylinder 50 toward the hydraulic oil source HS is shown by a thick dotted line, as in Fig. 4, and the oil passage through which the hydraulic oil flows from the hydraulic oil source HS toward the auxiliary cylinder 50 is shown by a thick solid line. Also, in Fig. 5, the flow of hydraulic oil is shown by arrows.

[0033] Specifically, as shown by the block arrows, when the auxiliary cylinder 50 contracts, the volume of the bottom-side oil chamber BC of the auxiliary cylinder 50 contracts, and the hydraulic oil in the bottom-side oil chamber BC flows out of the bottom-side oil chamber BC. On the other hand, the volume of the head-side oil chamber HC of the auxiliary cylinder 50 expands, and the hydraulic oil in the oil passage CD flows into the head-side oil chamber HC.

[0034] The contraction of the auxiliary cylinder 50 occurs, for example, when the platform 64 to which the cab 10 is fixed moves downward. The downward movement of the platform 64 occurs, for example, when the work machine 100 swings in the front-rear or left-right direction due to a change in the work load on the end attachment 6. Alternatively, the downward movement of the platform 64 occurs, for example, when the work machine 100 swings in the front-rear or left-right direction while the work machine 100 is traveling. Alternatively, the downward movement of the platform 64 occurs when the emergency lowering mechanism is activated.

[0035] The emergency lowering mechanism is a mechanism for lowering the cab 10 in an emergency. In the illustrated example, the emergency lowering mechanism includes a switch ES (see FIG. 2) installed at the bottom of the support tower body 63. An operator or the like outside the cab 10 can lower the cab 10 by operating the switch ES. Specifically, the emergency lowering mechanism is configured to use the weight of the cab 10 to cause the hydraulic oil in the bottom-side oil chamber of the lifting cylinder 62 to flow out of the lifting cylinder 62 and contract the lifting cylinder 62, thereby lowering the cab 10. An operator or the like can operate the switch ES to open an opening / closing valve (stop valve) provided in an oil passage connecting the bottom-side oil chamber of the lifting cylinder 62 and the hydraulic oil tank, thereby allowing the hydraulic oil in the bottom-side oil chamber of the lifting cylinder 62 to flow out to the hydraulic oil tank. The stop valve may be configured to be opened and closed without the switch ES, that is, to be opened and closed manually.

[0036] Specifically, the hydraulic oil flowing out from the bottom oil chamber BCL of the left auxiliary cylinder 50L passes through the eleventh oil passage CD11, the tenth oil passage CD10, the ninth oil passage CD9, and the first oil passage CD1 to the hydraulic oil source HS. The hydraulic oil flowing out from the bottom oil chamber BCR of the right auxiliary cylinder 50R passes through the twelfth oil passage CD12 to the sixth connection point CP6, and merges with the flow of hydraulic oil from the bottom oil chamber BCL of the left auxiliary cylinder 50L toward the hydraulic oil source HS at the sixth connection point CP6. The check valve 41B provided in the eighth oil passage CD8 blocks the flow of hydraulic oil from the auxiliary cylinder 50 toward the hydraulic oil source HS. Therefore, the hydraulic oil flowing out from the bottom oil chamber BC of the auxiliary cylinder 50 flows toward the hydraulic oil source HS through the ninth oil passage CD9, not the eighth oil passage CD8. Since the ninth oil passage CD9 is provided with the fixed throttle valve 42B, the flow resistance of the ninth oil passage CD9 when the hydraulic oil flows from the auxiliary cylinder 50 to the hydraulic oil source HS is greater than the flow resistance of the eighth oil passage CD8 when the hydraulic oil flows from the hydraulic oil source HS to the auxiliary cylinder 50. As a result, the contraction speed of the auxiliary cylinder 50 is limited by the fixed throttle valve 42B. Note that, the smaller the opening area of ​​the fixed throttle valve 42B, the greater the restriction on the contraction speed of the auxiliary cylinder 50, the greater the movement resistance during contraction of the auxiliary cylinder 50, and the slower the contraction speed of the auxiliary cylinder 50.

[0037] On the other hand, the hydraulic oil in the hydraulic circuit HT flows from the first connection point CP1 through the second oil passage CD2, the third oil passage CD3, and the fifth oil passage CD5 to the fourth connection point CP4, and then branches into two at the fourth connection point CP4. One of the two branches flows into the head side oil chamber HCL of the left auxiliary cylinder 50L through the sixth oil passage CD6, and the other flows into the head side oil chamber HCR of the right auxiliary cylinder 50R through the seventh oil passage CD7. The fixed throttle valve 42H provided in the fourth oil passage CD4 makes the flow resistance of the fourth oil passage CD4 larger than the flow resistance of the third oil passage CD3, so that most of the hydraulic oil from the first connection point CP1 flows through the third oil passage CD3. The check valve 41H provided in the third oil passage CD3 does not impede the flow of the hydraulic oil from the first connection point CP1 toward the auxiliary cylinder 50.

[0038] As described above, the work machine 100 according to the embodiment of the present disclosure includes, as shown in Fig. 1, the cab 10, the lifting cylinder 62 which is a single-rod hydraulic cylinder that raises and lowers the cab 10, and an extendable suppression mechanism RM that suppresses movement of the cab 10. The suppression mechanism RM may be configured with a gas damper, a gas spring, an oil damper, or the like, or may be configured with an air cylinder or a hydraulic cylinder. In the illustrated example, the suppression mechanism RM is a single-rod hydraulic cylinder.

[0039] With this configuration, the work machine 100 can suppress rocking of the cab 10, thereby improving the comfort of the operator in the cab 10. That is, the work machine 100 can suppress rocking of the cab 10 during operation due to the damper effect of the auxiliary cylinder 50, thereby improving the comfort of the operator in the cab 10.

[0040] The working machine 100 may be provided with a cab lifting mechanism 60 including a plurality of movable members. In the example shown in FIG. 2, the plurality of movable members include a platform 64, an upper link 69, and a lower link 70. The upper end of the lifting cylinder 62 is connected to one of the plurality of movable members, and the upper end of the suppression mechanism RM is connected to another one of the plurality of movable members. In the example shown in FIG. 2, the upper end of the lifting cylinder 62 is connected to the upper link 69. The upper end of the auxiliary cylinder 50, which is an example of the suppression mechanism RM, is connected to the lower link 70. That is, the upper ends of the lifting cylinder 62 and the suppression mechanism RM are connected to different movable members. For example, when the upper end of the lifting cylinder 62 is connected to the platform 64, the upper end of the auxiliary cylinder 50 may be connected to the upper link 69, or the upper end of the auxiliary cylinder 50 may be connected to the lower link 70. Alternatively, when the upper end of the lifting cylinder 62 is connected to the upper link 69, the upper end of the auxiliary cylinder 50 may be connected to the frame 64. In the illustrated example, the lower ends of the lifting cylinder 62 and the suppression mechanism RM are connected to the support tower body 63. However, the lower end of at least one of the lifting cylinder 62 and the suppression mechanism RM may be connected to another rigid body such as the revolving frame AF.

[0041] This configuration brings about the effect of increasing the stability of support of the cab 10 by the lifting cylinder 62 and the suppression mechanism RM compared to a case in which the upper ends of the lifting cylinder 62 and the suppression mechanism RM are connected to the same movable member. This is because it is possible to prevent the load of the cab 10 from concentrating on the same movable member. However, the upper ends of the lifting cylinder 62 and the suppression mechanism RM may be connected to the same movable member.

[0042] The suppression mechanism RM is preferably configured to be in an extendable state even when the cab 10 is located at either the upper limit position or the lower limit position. In the illustrated example, the auxiliary cylinder 50 is configured not to extend to the stroke end even when the cab 10 is located at the upper limit position, and not to contract to the stroke end even when the cab 10 is located at the lower limit position. On the other hand, the lifting cylinder 62 is configured to extend to the stroke end when the cab 10 is located at the upper limit position, and to contract to the stroke end when the cab 10 is located at the lower limit position. However, like the auxiliary cylinder 50, the lifting cylinder 62 may also be configured not to extend to the stroke end even when the cab 10 is located at the upper limit position, and may also be configured not to contract to the stroke end even when the cab 10 is located at the lower limit position.

[0043] With this configuration, the suppression mechanism RM can suppress rocking of the cab 10 whether the cab 10 is positioned at the upper limit position or the lower limit position, thereby improving the comfort of the operator inside the cab 10. For example, the suppression mechanism RM can suppress rocking of the cab 10 when the work machine 100 is traveling with the cab 10 positioned at the lower limit position.

[0044] The suppression mechanism RM may be an auxiliary cylinder 50, which is a single-rod hydraulic cylinder, as shown in Fig. 2. In this case, the auxiliary cylinder 50 may be configured to expand and contract in a state in which the head side oil chamber HC and the bottom side oil chamber BC are in communication with a common hydraulic oil source HS, as shown in Fig. 3.

[0045] With this configuration, the suppression mechanism RM can suppress the rocking of the cab 10 without using a pressure source such as a hydraulic pump or an accumulator, thereby improving the comfort of the operator inside the cab 10.

[0046] The work machine 100 may be provided with an emergency lowering mechanism for forcibly lowering the cab 10. In this case, the lowering speed of the cab 10 when the emergency lowering mechanism is operated may be limited by the suppression mechanism RM. In the illustrated example, the emergency lowering mechanism is configured to lower the cab 10 by causing the hydraulic oil in the bottom-side oil chamber of the lift cylinder 62 to flow out from the bottom-side oil chamber of the lift cylinder 62 to contract the lift cylinder 62. The opening area of ​​the fixed throttle valve 42B provided in the ninth oil passage CD9 in the hydraulic circuit HT shown in FIG. 3 is set so that the contraction speed of the auxiliary cylinder 50 is smaller than the contraction speed of the lift cylinder 62 when the emergency lowering mechanism is operated.

[0047] With this configuration, the suppression mechanism RM can gradually lower the cab 10 while supporting it, even if the pressure of the hydraulic oil in the bottom oil chamber of the lift cylinder 62 is lower than a predetermined pressure. The predetermined pressure is, for example, a pressure required to support the cab 10 by the lift cylinder 62 alone.

[0048] The lift cylinder 62 may be configured to extend by hydraulic oil discharged from the hydraulic pump. The suppression mechanism RM may be configured to extend in response to the extension of the lift cylinder 62, without relying on hydraulic oil discharged from the hydraulic pump. In the illustrated example, the hydraulic pump is a variable displacement hydraulic pump that is driven by a drive source such as a diesel engine mounted on the work machine 100, and supplies hydraulic oil to hydraulic actuators such as the boom cylinder 7, the arm cylinder 8, the end attachment cylinder 9, the swing hydraulic motor, and the traveling hydraulic motor.

[0049] With this configuration, the suppression mechanism RM can suppress the shaking of the cab 10 without using the relatively high pressure hydraulic oil discharged by the hydraulic pump, thereby improving the comfort of the operator inside the cab 10.

[0050] The auxiliary cylinder 50 may be composed of one or more single-rod hydraulic cylinders. The lifting cylinder 62 may be composed of one or more single-rod hydraulic cylinders. In the illustrated example, the auxiliary cylinder 50 is composed of a pair (two) of left and right single-rod hydraulic cylinders (a left auxiliary cylinder 50L and a right auxiliary cylinder 50R), and the lifting cylinder 62 is composed of one single-rod hydraulic cylinder arranged between the left auxiliary cylinder 50L and the right auxiliary cylinder 50R. However, the auxiliary cylinder 50 may be composed of one single-rod hydraulic cylinder arranged between a pair (two) of left and right lifting cylinders composed of single-rod hydraulic cylinders, for example.

[0051] When the auxiliary cylinder 50 is composed of a plurality of single-rod hydraulic cylinders, the upper ends of the plurality of hydraulic cylinders may be connected to different movable members. The same applies to the case where the lift cylinder 62 is composed of a plurality of single-rod hydraulic cylinders. In the illustrated example, the auxiliary cylinder 50 and the lift cylinder 62 are each an upright hydraulic cylinder in which the head-side oil chamber is arranged on the upper side and the bottom-side oil chamber is arranged on the lower side, but at least one of the auxiliary cylinder 50 and the lift cylinder 62 may be an inverted hydraulic cylinder in which the head-side oil chamber is arranged on the lower side and the bottom-side oil chamber is arranged on the upper side.

[0052] This configuration brings about the effect of increasing the degree of freedom in arranging the auxiliary cylinder 50 and the lift cylinder 62.

[0053] The head side oil chamber HC of the auxiliary cylinder 50 and the hydraulic oil source HS may be connected by a first inflow oil passage (third oil passage CD3) and a first outflow oil passage (fourth oil passage CD4) arranged in parallel, as shown in FIG. 3. In this case, a first flow direction restricting unit (check valve 41H) that allows the hydraulic oil to flow from the hydraulic oil source HS to the head side oil chamber HC and restricts the hydraulic oil flow from the head side oil chamber HC to the hydraulic oil source HS may be arranged in the first inflow oil passage (third oil passage CD3), and a first flow rate restricting unit (fixed throttle valve 42H) that restricts the flow rate of the hydraulic oil flowing from the head side oil chamber HC to the hydraulic oil source HS may be arranged in the first outflow oil passage (fourth oil passage CD4). In addition, the bottom side oil chamber BC of the auxiliary cylinder 50 and the hydraulic oil source HS may be connected by a second inflow oil passage (eighth oil passage CD8) and a second outflow oil passage (ninth oil passage CD9) arranged in parallel, as shown in FIG. 3. In this case, a second flow direction restriction unit (check valve 41B) is provided in the second inlet oil passage (8th oil passage CD8) to allow the flow of hydraulic oil from the hydraulic oil source HS toward the bottom side oil chamber BC and to restrict the flow of hydraulic oil from the bottom side oil chamber BC toward the hydraulic oil source HS, and a second flow rate restriction unit (fixed throttle valve 42B) may be provided in the second outlet oil passage (9th oil passage CD9) to restrict the flow rate of hydraulic oil flowing from the bottom side oil chamber BC to the hydraulic oil source HS.

[0054] Specifically, the first flow direction restricting portion may be a check valve 41H or a switching valve. The second flow direction restricting portion may be a check valve 41B or a switching valve. The first flow rate restricting portion may be a fixed throttle valve 42H, a variable throttle valve, or a switching valve. The second flow rate restricting portion may be a fixed throttle valve 42B, a variable throttle valve, or a switching valve.

[0055] This configuration brings about an effect that the suppression of the rocking of the cab 10 by the suppression mechanism RM (auxiliary cylinder 50) is realized by a simple hydraulic circuit HT.

[0056] The preferred embodiments of the present invention have been described above in detail. However, the present invention is not limited to the above-described embodiments. Various modifications or substitutions may be applied to the above-described embodiments without departing from the scope of the present invention. Furthermore, features described separately may be combined unless technical contradictions arise. [Explanation of symbols]

[0057] 1 lower running body 2 swivel mechanism 3 upper swivel body 4 boom 5 arm 6 end attachment 7 boom cylinder 8 arm cylinder 9 end attachment cylinder 10 cab 41 flow direction restricting section 41B, 41H check valve 42 flow rate restricting section 42B, 42H fixed throttle valve 50 auxiliary cylinder 50L left auxiliary cylinder 50La rod 50R right auxiliary cylinder 50Ra rod 51 upper connecting member 51L upper left connecting member 51R upper right connecting member 52 upper rod pin 52L upper left rod pin 52R upper right rod pin 53 lower connecting member 53L···Left lower connecting member 53R···Right lower connecting member 54···Lower cylinder pin 54L···Lower left cylinder pin 54R···Lower right cylinder pin 60···Cab lifting mechanism 61···Parallel link mechanism 62···Lifting cylinder 62a···Rod 63···Support tower body 64···Frame 65···First lower end pin 66···Second lower end pin 67···First upper end pin 68···Second upper end pin 69···Upper link 70···Lower link 71···Cylinder pin 72···Rod pin AF···Swivel frame BC, BCL, BCR··Bottom oil chamber CD···Oil passage CD1···First oil passage CD2···Second oil passage CD3...3rd oilway CD4...4th oilway CD5...5th oilway CD6...6th oilway CD7...7th oilway CD8...8th oilway CD9...9th oilway CD10...10th oilway CD11...11th oilway CD12...12th oilway CP1...1st connection point CP2...2nd connection point CP3...3rd connection point CP4...4th connection point CP5...5th connection point CP6...6th connection point ES...Switch HC, HCL, HCR...Head side oil chamber HS...Hydraulic oil source HT...Hydraulic circuit RM...Suppression mechanism

Claims

1. Cab and A lifting cylinder for lifting and lowering the cab; and a retractable restraining mechanism for restraining movement of the cab. Working machinery.

2. A cab lifting mechanism including a plurality of movable members is provided, The lift cylinder has an upper end connected to one of the plurality of movable members, The suppression mechanism has an upper end connected to another one of the plurality of movable members.

2. The work machine of claim 1.

3. The restraining mechanism is configured to be in an extendable and retractable state even when the cab is in either the upper limit position or the lower limit position.

2. The work machine of claim 1.

4. the suppression mechanism is an auxiliary cylinder which is a single-rod hydraulic cylinder, The auxiliary cylinder is configured to expand and contract in a state in which the head side oil chamber and the bottom side oil chamber are connected to a common hydraulic oil source.

2. The work machine of claim 1.

5. An emergency lowering mechanism for forcibly lowering the cab is provided, The descent speed of the cab when the emergency descent mechanism is activated is limited by the suppression mechanism.

2. The work machine of claim 1.

6. The lift cylinder is extended by hydraulic oil discharged from a hydraulic pump, The suppression mechanism extends in response to the extension of the lift cylinder, without depending on the hydraulic oil discharged by the hydraulic pump.

2. The work machine of claim 1.

7. The auxiliary cylinder is composed of one or more single rod hydraulic cylinders, The lift cylinder is composed of one or more single-rod hydraulic cylinders.

5. A work machine according to claim 4.

8. a head side oil chamber of the auxiliary cylinder and the hydraulic oil source are connected by a first inlet oil passage and a first outlet oil passage arranged in parallel, A first flow direction restricting portion is disposed in the first inflow oil passage, the first flow direction restricting portion permitting a flow of hydraulic oil from the hydraulic oil source toward the head side oil chamber and restricting a flow of hydraulic oil from the head side oil chamber toward the hydraulic oil source, A first flow rate restricting portion that restricts a flow rate of hydraulic oil flowing from the head side oil chamber to the hydraulic oil source is disposed in the first outflow oil passage, The bottom side oil chamber of the auxiliary cylinder and the hydraulic oil source are connected by a second inlet oil passage and a second outlet oil passage arranged in parallel, a second flow direction restricting portion is disposed in the second inflow oil passage, the second flow direction restricting portion permitting a flow of hydraulic oil from the hydraulic oil source toward the bottom-side oil chamber and restricting a flow of hydraulic oil from the bottom-side oil chamber toward the hydraulic oil source; A second flow rate restricting portion that restricts a flow rate of the hydraulic oil flowing from the bottom side oil chamber to the hydraulic oil source is disposed in the second outflow oil passage. A work machine according to claim 4 or claim 7.

9. The first flow direction restricting portion is a check valve or a switching valve, The second flow direction restricting portion is a check valve or a switching valve, The first flow rate restricting portion is a fixed throttle valve, a variable throttle valve, or a switching valve, The second flow rate restricting unit is a fixed throttle valve, a variable throttle valve, or a switching valve.

9. A work machine according to claim 8.

10. The movable member includes a base, an upper link, and a lower link; The lift cylinder has an upper end connected to the upper link, The suppression mechanism has an upper end connected to the lower link.

3. A work machine according to claim 2.

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