JP2006283854A - Traveling motor controller of construction machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To securely suppress the occurrence of cavitation without using a counterbalance valve and prevent the rise of a traveling speed at starting from being delayed. <P>SOLUTION: This traveling motor controller comprises a traveling motor 20 and a motor control valve 21. The motor control valve 21 controls the motor 20 by changing over the connected state thereof to a pump and a tank based on a pilot pressure instruction from a remote control valve 22 and the inflow side pressure of the motor 20. A pilot pressure control valve 23 connects the pilot chamber 24 of the control valve 21 to the tank at a discharge position 25a, and connects it to the remote control valve 22 at a feed position 25b. A spring 26 energizes the control valve 23 to the discharge position 25a side and energizes the pilot chamber 27 to the feed position 25b side by the action of the inflow side pressure. A starting passage 28 connects the remote control valve 2 to the pilot chamber 24 through the control valve 21. The passage 28 is allowed to communicate until its position is changed over to the position 25b, and cut off by the control valve 21 when it is changed over to the position 25b. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The traveling motor connected to the pump and the tank via the swivel joint and the connection state of the pump and the tank to the traveling motor are switched to control the traveling motor to any one of the stopped state, the forward rotation state, and the reverse rotation state. The present invention relates to a traveling motor control device for a construction machine including a motor control valve.

  2. Description of the Related Art Conventionally, a construction machine travel motor control device (hereinafter also simply referred to as “travel motor control device”) including a travel motor and a motor control valve that controls the operation state thereof is known (see, for example, Patent Document 1). . Conventionally, a counter balance valve has been used to prevent cavitation in the traveling motor, whereas in the traveling motor control device described in Patent Document 1, counter balancing is used from the viewpoint of simplifying the valve structure. The object is to realize a structure that can prevent cavitation without using a valve. In this travel motor control device, the main switching valve (14A) provided in the circuit connecting the hydraulic pump (10A) and the actuator (12), which is a hydraulic motor, is switched by the operation of the pilot valve (28). It has become. And, in response to the pressure oil from the pump (10A), the pipe line between the pilot chamber and the pilot valve (28) provided at both ends of the main switching valve (14A) responds to the decrease in the pump pressure. Pressure reducing valves (30a, 30b) for reducing the set pressure are provided.

JP-A-60-249707 (page 2-3, FIG. 2)

  However, in the travel motor control device described in Patent Document 1, in order to enable the switching operation from the neutral position of the main switching valve (14), the passage (56) on the discharge side of the pump (10A) is provided. The passage (26a, 26b) between the remote control valve (28) and the pilot chamber of the main switching valve (14) seems to be in a sufficiently communicated state in an initial state at the start of switching when no load is generated. In addition, the pressure reducing valves (30a, 30b) need to be formed. For this reason, in this traveling motor control device, when the pressure of the passage (56) decreases due to the construction machine starting to self-travel on a downhill or the like, the pressure reducing valve particularly in the initial state at the start of switching described above. There is a possibility that the pressure reduction due to (30a, 30b) cannot be sufficiently achieved, and there is a possibility that cavitation may occur in the traveling motor.

  Further, from the viewpoint of preventing the occurrence of cavitation due to the above-described causes, the passage (56) between the remote control valve (28) and the pilot chamber of the main switching valve (14) in the initial state at the start of switching. It is conceivable to form the pressure reducing valves (30a, 30b) so as to reduce the communication opening degree. However, when the pressure reducing valves (30a, 30b) are formed in this way, the pilot pressure acting on the pilot chamber of the main switching valve (14) in the initial state at the start of switching decreases (pressure oil supplied to the pilot chamber). There is a problem that the switching operation of the main switching valve (14) is delayed and the rise of the running speed at the start is delayed.

  In view of the above circumstances, the present invention relates to a traveling motor control device for a construction machine, and can more reliably suppress the occurrence of cavitation without using a counterbalance valve, and the rising of the traveling speed at start-up becomes slow. It is an object of the present invention to provide a traveling motor control device for a construction machine that can prevent the occurrence of the above.

Means and effects for solving the problems

A travel motor control device for a construction machine according to the present invention switches a travel motor connected to a pump and a tank via a swivel joint, and stops the travel motor by switching a connection state of the pump and the tank to the travel motor. A motor control valve that controls the state, the normal rotation state, or the reverse rotation state, and the motor control valve has a neutral position for setting the stop state, a normal rotation position for setting the normal rotation state, and the reverse rotation The neutral position or the forward rotation position or the reverse rotation position based on the command from the steering device operated by the pilot and the pressure on the inflow side of the pressure oil to the travel motor. The present invention relates to a traveling motor control device for a construction machine that switches to
And the traveling motor control apparatus of the construction machine which concerns on this invention has the following some features, in order to achieve the said objective. That is, the traveling motor control device for a construction machine according to the present invention includes the following features alone or in combination as appropriate.

  In order to achieve the above object, the first feature of the traveling motor control device for a construction machine according to the present invention is a remote control valve, which is the steering device for generating a pilot pressure, and the motor control valve. A pilot pressure control valve for switching a connection state between the first pilot chamber to which the pilot pressure is applied to switch the valve and the remote control valve and the first pilot chamber, and the first pilot chamber and the first pilot chamber; A pilot pressure control valve having a discharge position for connecting a tank and a supply position for connecting the remote control valve and the first pilot chamber; and disposed on one side of the pilot pressure control valve, A spring that biases the pilot pressure control valve toward the position side, and is disposed on the other side of the pilot pressure control valve; Start connecting the second pilot chamber in which the pressure on the inflow side acts to urge the pilot pressure control valve toward the front, the remote control valve, and the first pilot chamber via the motor control valve And the remote control valve and the first pilot chamber are connected via the starting passage until the pilot pressure control valve is switched to the supply position, and the supply position is When the switching is performed, the start passage is blocked by the motor control valve.

According to this configuration, the remote control valve and the first pilot chamber are connected via the start passage even until the pilot pressure control valve is switched to the supply position. For this reason, the pilot pressure control valve can be formed so as to reduce or block the opening at the discharge position, and sufficient pilot pressure can be applied to the first pilot chamber until the opening is switched to the supply position. . Thus, it is possible to prevent the switching operation from being delayed in the initial state at the start of switching when the motor control valve is switched from the neutral position, and the rising of the running speed at the start from being delayed. Then, after the pilot pressure control valve is switched to the supply position, the start passage is blocked by the motor control valve, and the pilot pressure acts on the first pilot chamber only through the pilot pressure control valve.
Further, when the pressure on the inflow side of the pressure oil to the traveling motor decreases when the construction machine starts to self-run, the pressure of the pressure oil acting on the second pilot chamber decreases. For this reason, the pilot pressure control valve is switched to the discharge position by the biasing force of the spring, and the passage between the remote control valve and the first pilot chamber shifts to a more narrowed state or a blocked state. Become. As a result, the motor control valve can be moved toward the neutral position side, and the pressure oil outflow side in the travel motor can be quickly shifted to a more narrowed state, thereby suppressing the occurrence of cavitation in the travel motor. it can.
Therefore, according to the configuration of the present invention, the traveling motor control device for a construction machine can more reliably suppress the occurrence of cavitation without using a counter balance valve, and the rising of the traveling speed at the time of starting will be delayed. Therefore, it is possible to provide a traveling motor control device for a construction machine that can prevent the above.

  Further, a second feature of the traveling motor control device for a construction machine according to the present invention is that the start passage is blocked when the motor control valve is switched from the neutral position to the forward rotation position or the reverse rotation position. After this is done, the pressure oil outflow side from the travel motor is connected to the tank.

  According to this configuration, when the motor control valve is switched from the neutral position, the start passage is first shut off, and then the outflow side of the travel motor and the tank are connected. For this reason, even if the construction machine starts to self-run at the time of switching and the pressure on the outflow side of the travel motor decreases, the outflow side of the travel motor is blocked by the motor control valve until the start passage is shut off. Thus, the occurrence of cavitation can be further suppressed.

  A third feature of the traveling motor control device for a construction machine according to the present invention is that the pressure from the traveling motor is changed when the motor control valve is switched from the neutral position to the forward rotation position or the reverse rotation position. After the oil outflow side and the tank are connected, the starting passage is blocked.

  According to this configuration, even when the construction machine starts to self-run at the time of switching and the pressure on the outflow side of the traveling motor decreases and the pilot pressure control valve does not sufficiently switch to the supply position side, the first pilot chamber Since the pilot pressure acts through the starting passage, the outflow side of the traveling motor in the motor control valve is not suddenly shut off, and the occurrence of impact can be suppressed.

  According to a fourth feature of the traveling motor control device for a construction machine according to the present invention, the motor control valve is a center bypass type control valve, and the discharge of the pump is performed when the start passage is shut off. Even when the amount is minimum, a pressure capable of switching the pilot pressure control valve to the supply position against the biasing force of the spring is generated on the inflow side of the traveling motor and is generated in the second pilot chamber. That is, the opening degree of the center bypass passage is set so as to act.

According to this configuration, since the path on which the pilot pressure acts on the first pilot chamber can be smoothly switched from the starting passage to the passage through the pilot pressure control valve, the impact at the start of the travel motor, That is, the impact at the time of switching the pilot pressure control valve can be reduced.
In addition, when this configuration is applied to the traveling motor control device for a construction machine having the second feature, the pilot pressure is applied to the first pilot chamber before the traveling motor is started and its outflow side is opened. Since the acting route is switched to the passage via the pilot pressure control valve, it is possible to prevent the traveling motor from generating an impact when the pilot pressure control valve is switched.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 illustrates a hydraulic circuit provided with a traveling motor control device for a construction machine according to an embodiment of the present invention. The construction machine in which the hydraulic circuit 10 shown in FIG. 1 is disposed includes a lower body configured as a crawler vehicle body and an upper body disposed above the lower body. The swivel joint 11 is arranged in the. In this construction machine, at least two hydraulic pumps of the first pump 12 and the second pump 13 and a tank 14 are arranged in the upper body, and various types of pressure oil are supplied from these pumps (12, 13). A hydraulic actuator is provided. The lower body is provided with a traveling motor connected to the pumps (12, 13) and the tank 14 via the swivel joint 11. The construction machine is provided with a right traveling motor 20 and a left traveling motor, but only one right traveling motor 20 is shown in FIG. On the other hand, the upper body is provided with a bucket cylinder that operates the bucket, a boom cylinder that operates the boom, a swing motor, an arm cylinder that operates the arm, and the like as other hydraulic actuators different from the travel motor. .

  As shown in FIG. 1, the hydraulic circuit 10 of the construction machine includes a main control valve 15 disposed in the upper body and the travel motor control device 1 (hereinafter simply referred to as “travel motor”) of the construction machine according to the present embodiment. Control device 1 ”).

  The main control valve 15 includes a swing direction switching valve 16 that controls the supply of pressure oil to the swing motor, an arm direction switching valve 17 that controls the supply of pressure oil to the arm cylinder, and the pressure oil to the bucket cylinder. A bucket direction switching valve 18 that controls supply, a boom direction switching valve 19 that controls supply of pressure oil to the boom cylinder, and the like are provided. The swing direction switching valve 16 and the arm direction switching valve 17 are connected to the downstream side of the first pump 12, and the bucket direction switching valve 18 and the boom direction switching valve 19 are downstream of the second pump 13. It is connected to the.

  The travel motor control device 1 includes a right travel motor 20, a left travel motor, and the like. Further, the traveling motor control device 1 includes a motor control valve 21 corresponding to the right traveling motor 20, a remote control valve 22, a pilot pressure control valve 23 (23a, 23b), and the like, and similarly illustrated corresponding to the left traveling motor. A motor control valve, a remote control valve, a pilot pressure control valve, and the like that are not included are configured (in FIG. 1, only those corresponding to the right travel motor 20 are illustrated). In the following description of the travel motor control device 1, only the right travel motor 20 and its motor control valve 21 will be described, and the left travel motor and its motor control valve will not be described because they overlap.

  As described above, the travel motor 20 of the travel motor control device 1 is disposed in the lower body, and the motor control valve 21 and the pilot pressure control valve 23 are also disposed in the lower body. On the other hand, the remote control valve 22 is disposed on the upper body. The motor control valve 21 is integrally attached to the travel motor 20 (is integrally formed). The motor control valve 21 is tandemly or serially connected to the control valves (16, 17, 18, 19) of other hydraulic actuators, and downstream of the control valves (16 to 19) of these other hydraulic actuators. On the side.

  The motor control valve 21 switches the connection state of the pumps (12, 13) and the tank 14 to the travel motor 20 to stop the travel motor 20, and the normal rotation state (the state in which the construction machine rotates in the forward direction). , And a reverse rotation state (a state in which the construction machine rotates in the reverse direction). The motor control valve 21 has a neutral position 21a, forward rotation positions 21b and 21c, and reverse rotation positions 21d and 21e. When the motor control valve 21 is switched to the neutral position 21a, the traveling motor 20 is stopped. On the other hand, when the travel motor control valve 21 is switched to the forward rotation position 21b (or 21c), the travel motor 20 is in the forward rotation state, and when the travel motor control valve 21 is switched to the reverse rotation position 21d (or 21e), It is comprised so that it may be in a reverse rotation state. As will be described later, the motor control valve 21 has a neutral position 21a, forward rotation positions 21b and 21c, and reverse rotation positions 21d and 21e based on a command from the remote control valve 22 and pressure on the inflow side of pressure oil to the traveling motor 20. It is configured to switch to any one of the positions.

  The motor control valve 21 is provided with a pilot chamber 24 (24a, 24b) in which a pilot pressure for switching the motor control valve 21 is applied. When the pilot pressure is applied to the pilot chamber 24a, the motor control valve 21 is switched from the neutral position 21a to the forward rotation position 21b and further to the forward rotation position 21c. When the pilot pressure is applied to the pilot chamber 24b, the motor control valve 21 is switched. Is switched from the neutral position 21a to the reverse rotation position 21d and further to the reverse rotation position 21e. Pilot pressure acting on the pilot chamber 24 is generated by the remote control valve 22. That is, the remote control valve 22 constitutes a control device that generates a command based on a pilot pressure based on the operation of a construction machine operator (not shown). The pilot chamber 24 constitutes the first pilot chamber in the present embodiment.

  Further, the traveling motor control device 1 further includes a pilot pressure control valve 23 for switching a connection state between the remote control valve 22 and the pilot chamber 24 of the motor control valve 21, a spring 26 provided in the pilot pressure control valve 23, and a pilot. A chamber 27 and a start passage 28 are provided.

  The pilot pressure control valve 23 includes a pilot pressure control valve 23a that switches a connection state with the pilot chamber 24a and a pilot pressure control valve 23b that switches a connection state with the pilot chamber 24b. These pilot pressure control valves 23 are connected to a discharge position 25a for connecting the pilot chamber 24 and the tank 14, and a supply position 25b for connecting the passage 29 for pilot pressure from the remote control valve 22 to the pilot chamber 24. And have.

  The spring 26 is disposed on one side of the pilot pressure control valve 23 and biases the pilot pressure control valve 23 in a direction in which the pilot pressure control valve 23 switches to the discharge position 25a side. ing. On the other hand, the pilot chamber 27 is disposed on the other side of the pilot pressure control valve 23, and urges the pilot pressure control valve 23 in a direction in which the pilot pressure control valve 23 switches to the supply position 25b side. As described above, the pressure of the pressure oil on the inflow side to the travel motor 20 acts through the passage 30. The pilot chamber 27 constitutes the second pilot chamber in the present embodiment.

  With the pilot pressure control valve 23, the spring 26, and the pilot chamber 27 having the above-described configuration, the motor control valve 21 is switched in accordance with the switching of the pilot pressure control valve 23. For example, when the pressure oil pressure on the inflow side of the traveling motor 20 acts on the pilot chamber 27 of the pilot pressure control valve 23a, the pilot pressure control valve 23a is switched to the supply position 25b against the urging force of the spring 26. The pilot pressure from the remote control valve 22 guided through the passage 29 acts on the pilot chamber 24a. As a result, the motor control valve 21 is switched to the forward rotation position 21b or 21c. On the other hand, when the urging force due to the pressure oil acting on the pilot chamber 27 becomes smaller than the urging force of the spring 26 and the pilot pressure control valve 23a is switched to the discharge position 25a, the pilot pressure is applied to the pilot chamber 24a. The acting pressure oil is discharged to the tank 14 through the throttle 31. Then, the motor control valve 21 is switched from the normal rotation position 21c to the normal rotation position 21b and further to the neutral position 21a.

  The starting passage 28 (28a, 28b) is configured to connect the remote control valve 22 and the pilot chamber 24 via the motor control valve 21. The start passage 28a connects the remote control valve 22 and the pilot chamber 24a, and the start passage 28b connects the remote control valve 22 and the pilot chamber 24b. The starting passage 28 is a portion formed by a passage formed in the motor control valve 21. When the motor control valve 21 is in the neutral position 21a, the remote control valve 22, the pilot chamber 24, Is supposed to be connected. The starting passage 28a is blocked when the motor control valve 21 is in the forward rotation position 21b / 21c, and the starting passage 28b is blocked when the motor control valve 21 is in the reverse rotation position 21d / 21e.

  Next, the operation of the travel motor control device 1 will be described. The state shown in FIG. 1 shows a state where the motor control valve 21 is in the neutral position 21a. In this state, the traveling motor 20 is in a stopped state. When the construction machine provided with the traveling motor control device 1 is operated in a low temperature environment such as winter in a cold region, first, warm-up operation is performed. During this warm-up operation, the pressure oil (hydraulic oil) is circulated in a state where the pumps (12, 13) are activated and pressure oil is not supplied to the hydraulic actuators (states where the control valves are not operated).

  At this time, the pressure oil discharged from the pump (12, 13) is heated while circulating to the tank 14 via the control valves (16, 17, 18, 19, 21). It is also circulated through the path leading to the tank 14 disposed in the upper body via the motor control valve 21. That is, during the warm-up operation, the pressure oil discharged from the pumps (12, 13) circulates to the motor control valve 21 disposed in the lower body where the traveling motor 20 is disposed. For this reason, the motor control valve 21 is warmed by the pressure oil that has been circulated and warmed, and the traveling motor 20 in which the motor control valve 12 is integrally formed is also warmed.

  After the warm-up operation is performed, the left and right traveling motors are started and the construction machine starts to travel. Here, in order to move the construction machine forward, the traveling motor is operated in a normal rotation state. An example of the right traveling motor 20 in the case of In this case, first, when the remote control valve 22 is operated by the operator, a pilot pressure of a forward travel command (a travel command in the forward rotation direction) that is a pilot pressure acting via the passage 32 is generated.

  When the pilot pressure for the forward travel command is generated, the motor control valve 21 is in the neutral position 21a, so that the starting passage 28a is in communication, and the pilot pressure acts on the pilot chamber 24a via the starting passage 28a. become. At this time, the pilot pressure control valve 23a on the downstream side of the starting passage 28a is in the discharge position 25a due to the urging force of the spring 26 because the pressure oil on the inflow side of the traveling motor 20 is low. For this reason, the pressure oil generating the pilot pressure acting on the pilot chamber 24 a is discharged to the tank 14 through the start passage 28 a. However, since the throttle 31 is provided in the path to the tank 14 and the opening thereof is set to be appropriately throttled, the pilot pressure of the pressure necessary for the switching operation of the motor control valve 21 is used for starting. It is adjusted so as to act on the pilot chamber 24a through the passage 28a.

  Thus, when the pilot pressure acts on the pilot chamber 24a via the start passage 28a, the motor control valve 21 is switched to the forward rotation position 21b. Thereby, pressure oil is supplied in the direction in which the traveling motor 20 rotates in the normal rotation state, and the construction machine starts to move forward. Further, when the supply of pressure oil to the traveling motor 20 is started, the pressure of the pressure oil on the inflow side of the traveling motor 20 increases, and thus the increased pressure is supplied to the pilot of the pilot pressure control valve 23 a via the passage 30. Acts on the chamber 27. As a result, the pilot pressure control valve 23a is switched to the supply position 25b against the urging force of the spring 26, and the pilot pressure is applied to the pilot chamber 24a via the passage 29 and switched to the forward rotation position 21b or 21c. In this state, the motor control valve 21 is held. When the motor control valve 21 is switched to the forward rotation position 21b or 21c, the starting passage 28a is in a blocked state. Thus, in the traveling motor control device 1, the remote control valve 22 and the pilot chamber 24 are connected via the start passage 28 until the pilot pressure control valve 23 is switched to the supply position 25a, and the supply position 25a is connected. The start passage 28 is blocked by the motor control valve 21 when switching.

  Here, the switching operation from the neutral position 21a in the motor control valve 21 will be described in more detail. FIG. 2 shows changes in the opening area of each passage when the motor control valve 21 which is a center bypass type control valve switches from the neutral position 21a to the forward rotation position (21b, 21c) or the reverse rotation position (21d, 21e). FIG. In FIG. 2, a passage (P → N) that is a center bypass passage between point P and point N, and between point P and point Ma (pressure oil inflow side during forward rotation of the traveling motor 20). Passage (P → Ma), point Mb (pressure oil outflow side during forward rotation of the traveling motor 20) and the tank 14 (Mb → T), start between point R and point Pa The change of the opening area of the passage (R → Pa) or the like which is the passage 28 is shown. In FIG. 2, two patterns of the pattern I and the pattern II are illustrated for the change in the opening area of the passage (R → Pa). Pattern I shows a case where the starting passage 28 is formed in the motor control valve 21 so that the opening area changes as shown by a locus indicated by (R → Pa-I) in the drawing. On the other hand, the pattern II shows a case where the start passage 28 is formed in the motor control valve 21 so that the opening area changes like a locus (R → Pa-II) indicated by a dotted line in the drawing. .

  When switching of the motor control valve 21 is started from the neutral position 21a toward the forward rotation position (21b, 21c), the opening degree of the passage (P → N) that is the center bypass passage is narrowed, and the traveling motor 20 The opening of the inflow side passage (P → Ma) is gradually opened. At this time, the starting passage 28 (that is, the passage (R → Pa)) remains in communication. In the case of pattern I, when the motor control valve 21 switches from the neutral position 21a to the forward rotation position (21b, 21c), the passage (R → Pa) that is the starting passage 28 is shut off, The passage (Mb → T) between the outflow side of the pressure oil from the traveling motor 20 and the tank 14 is connected. On the other hand, in the case of Pattern II, when the motor control valve 21 is switched from the neutral position 21a to the forward rotation position (21b, 21c), the passage (Mb → T) is connected, and then the start passage 28. The passage (R → Pa) is blocked.

  Further, in either case of pattern I or pattern II, when the starting passage 28 is blocked, the opening degree of the passage (P → N) that is the center bypass passage seems to have a predetermined opening degree ΔA. Is set to This opening degree ΔA is such that the pressure of the travel motor 20 can switch the pilot pressure control valve 23a to the supply position 25b against the urging force of the spring 26 even when the discharge amount of the pump (12, 13) is in the minimum state. It is set so as to occur on the inflow side and to act on the pilot chamber 24a.

  In the traveling motor control device 1 described above, when the warming-up operation of the construction machine is performed, the pressure discharged from the pumps (12, 13) to the motor control valve 21 disposed in the lower body where the traveling motor 20 is disposed. Oil will circulate. For this reason, while the motor control valve 21 is warmed by the pressure oil circulated and warmed, the motor control valve 21 is also warmed to the travel motor 20 integrally formed. Therefore, according to the traveling motor control device 1, the traveling motor 20 is prevented from breaking the heat balance of the traveling motor 20 at the start of traveling after the warm-up operation, and causing a difference in thermal expansion in the traveling motor 20. The occurrence of malfunctions and failures can be suppressed.

  In addition, when the construction machine goes from a downhill traveling state to a stopped state, the pressure oil outflow side from the traveling motor 20 becomes a high pressure. For this reason, in the case of a traveling motor control device of a conventional construction machine, it is necessary to use a pipe having high strength so that it can withstand high pressure with respect to the pipe connecting the motor control valve and the traveling motor. Expensive piping is required. However, according to the travel motor control device 1, the motor control valve 21 is integrally formed with the travel motor 20, and therefore, a pipe that connects the motor control valve 21 and the travel motor 20 may be unnecessary. It becomes possible.

  In the traveling motor control device 1, the motor control valve 21 is connected in tandem (or serial connection) with the control valves of other hydraulic actuators other than the traveling motor 20, and the control valves (16 to 19) of the other hydraulic actuators. ) On the downstream side. Thus, the pressure oil supplied from the pumps (12, 13) is supplied to the motor control valve 21 after passing through the control valves (16 to 19) of the other hydraulic actuators. For this reason, the pressure loss due to the length of the pipe corresponding to the length corresponding to the arrangement of the motor control valve 21 in the lower body does not affect other hydraulic actuators. Accordingly, it is possible to suppress a decrease in energy efficiency.

  Further, in the traveling motor control device 1, the remote control valve 22 and the pilot chamber 24 are connected via the starting passage 28 even until the pilot pressure control valve 23 is switched to the supply position 25b. Therefore, the pilot pressure control valve 23 can be formed so as to reduce the opening at the discharge position 25a by providing the throttle 31, and sufficient pilot pressure can be applied to the pilot chamber 24 until the supply position 25b is switched. Can act. As a result, it is possible to prevent the switching operation from being delayed in the initial state at the start of switching when the motor control valve 21 is switched from the neutral position 21a, and the rising of the running speed at the start from being delayed. After the pilot pressure control valve 23 is switched to the supply position 25b, the start passage 28 is blocked by the motor control valve 21, and the pilot pressure acts on the pilot chamber 24 only through the pilot pressure control valve 23. become.

  Further, in the travel motor control device 1, when the pressure on the inflow side of the pressure oil to the travel motor 20 decreases when the construction machine starts to self-run, the pressure of the pressure oil acting on the pilot chamber 27 decreases. Therefore, the pilot pressure control valve 23 is switched to the discharge position 25a by the biasing force of the spring 26, and the passage between the remote control valve 22 and the pilot chamber 24 is shifted to a more narrowed state or a blocked state. It will be. As a result, the motor control valve 21 can be moved toward the neutral position 21a side, and the pressure oil outflow side of the travel motor 20 can be quickly shifted to a more narrowed state, and cavitation of the travel motor 20 can be generated. Can be suppressed.

  Therefore, according to the traveling motor control device 1, with respect to the traveling motor control device of the construction machine, the occurrence of cavitation can be more reliably suppressed without using the counter balance valve, and the rise of the traveling speed at the start is delayed. This can also be prevented.

  Further, in the traveling motor control device 1 formed so that the opening area of the start passage 28 in the motor control valve 21 changes in the example of the pattern I described above, when the motor control valve 21 is switched from the neutral position 21a, first, The starting passage 28 is blocked, and then the outflow side of the traveling motor 20 and the tank 14 are connected. For this reason, even if the construction machine starts to self-run at the time of switching and the pressure on the outflow side of the travel motor 20 decreases, the outflow side of the travel motor 20 is blocked by the motor control valve 21 until the start passage 28 is shut off. Therefore, the occurrence of cavitation can be further suppressed.

  In the travel motor control device 1 formed so that the opening area of the start passage 28 in the motor control valve 21 changes in the example of the pattern II described above, the construction machine starts to self-run at the time of switching, and the travel motor 20 Even if the pilot pressure control valve 23 is not sufficiently switched to the supply position 25b side because the pressure on the outflow side of the engine is reduced, the pilot pressure acts on the pilot chamber 24 via the start passage 28, so that the motor control The outflow side of the travel motor 20 in the valve 21 is not suddenly interrupted, and the occurrence of impact can be suppressed.

  Further, in the traveling motor control device 1, the opening degree of the passage (P → N) that is the center bypass passage is set so as to ensure the above-described predetermined opening degree ΔA. As a result, the path on which the pilot pressure acts on the pilot chamber 24 can be smoothly switched from the starting passage 28 to the passage through the pilot pressure control valve 23. The impact at the time of switching of the pilot pressure control valve 23 can be reduced. Further, in the case of the traveling motor control device 1 formed so that the opening area of the starting passage 28 in the motor control valve 21 changes in the above-described pattern II example, the traveling motor 20 is started and the outflow side thereof is opened. Before, the path on which the pilot pressure acts on the pilot chamber 24 has been switched to the path via the pilot pressure control valve 23, so that an impact is generated on the traveling motor 20 when the pilot pressure control valve 23 is switched. Can be prevented.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims.

1 illustrates a hydraulic circuit provided with a traveling motor control device for a construction machine according to an embodiment of the present invention. It is a figure explaining the change of the opening area of each channel | path when the position of a motor control valve switches in the traveling motor control apparatus shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Construction machine travel motor control apparatus 10 Hydraulic circuit 11 Swivel joint 12 1st pump 13 2nd pump 14 Tank 20 Traveling motor 21 Motor control valve 21a Neutral position 21b, 21c Forward rotation position 21d, 21e Reverse rotation position 22 Remote control valve (control apparatus)
23 Pilot pressure control valves 24, 24a, 24b First pilot chamber 25a Discharge position 25b Supply position 26 Spring 27 Second pilot chamber 28 Start passage

Claims (4)

A travel motor connected to the pump and the tank via a swivel joint, and a motor control for switching the connection state of the pump and the tank to the travel motor to control the travel motor to a stopped state, a normal rotation state, or a reverse rotation state. With a valve,
The motor control valve has a neutral position for making the stop state, a forward rotation position for making the forward rotation state, and a reverse rotation position for making the reverse rotation state, and is operated by the operator In a traveling motor control device for a construction machine that switches to the neutral position or the forward rotation position or the reverse rotation position based on a command from the apparatus and pressure on the inflow side of pressure oil to the traveling motor,
A remote control valve that is the steering device for generating a pilot pressure;
A first pilot chamber which is provided in the motor control valve and in which the pilot pressure for switching the motor control valve operates;
A pilot pressure control valve for switching a connection state between the remote control valve and the first pilot chamber, a discharge position for connecting the first pilot chamber and the tank, the remote control valve and the first pilot A pilot pressure control valve having a supply position connecting the chamber;
A spring disposed on one side of the pilot pressure control valve and biasing the pilot pressure control valve toward the discharge position;
A second pilot chamber that is disposed on the other side of the pilot pressure control valve and in which the pressure on the inflow side acts to urge the pilot pressure control valve toward the supply position;
A start passage connecting the remote control valve and the first pilot chamber via the motor control valve;
Further comprising
Until the pilot pressure control valve is switched to the supply position, the remote control valve and the first pilot chamber are connected via the start passage, and the motor control valve is switched to the supply position. The starter passage is blocked by the traveling motor control device for a construction machine.   When the motor control valve switches from the neutral position to the forward rotation position or the reverse rotation position, after the start passage is blocked, the pressure oil outflow side from the travel motor is connected to the tank. The traveling motor control device for a construction machine according to claim 1, wherein:   When the motor control valve switches from the neutral position to the forward rotation position or the reverse rotation position, the start passage is blocked after the pressure oil outflow side from the travel motor is connected to the tank. The traveling motor control device for a construction machine according to claim 1, wherein:   The motor control valve is a center bypass type control valve, and when the start passage is shut off, even when the discharge amount of the pump is at a minimum state, the motor control valve moves to the supply position against the biasing force of the spring. And the opening of the center bypass passage is set so that a pressure capable of switching the pilot pressure control valve is generated on the inflow side of the travel motor and acts on the second pilot chamber. The traveling motor control device for a construction machine according to any one of claims 1 to 3.

Images