JP2012102668A - Engine starter of working machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve damage prevention of gears due to erroneous starting operations with a simple system configuration and low cost.SOLUTION: An engine starter of a working machine includes: an engine 11; a starter circuit B for starting the engine 11 by actuating the starter 16 by the operation of the starter switch 14; and a hydraulic pump 12 driven by the engine 11, and for operating a hydraulic actuator circuit 13. A pressure switch 20 is provided in the starter circuit B, and power distribution to the starter 16 is permitted only when the discharge pressure of the hydraulic pump 12 is the preset value or less which indicates that the engine is almost stopped.

Description

  The present invention relates to an engine starting device that prevents a starting operation in a state where an engine is rotating in a working machine such as a hydraulic excavator.

  In a vehicle using an engine as a power source, as shown in FIG. 4, a starter circuit A including a starter switch 1, a starter relay 2, and a starter 3 is connected to a battery 4 as a power source. The starter relay 2 is actuated to drive the starter 3, and the engine is started by engaging the pinion 5 provided on the rotating shaft of the starter 3 with the ring gear 6 on the outer periphery of the flywheel of the engine ( (See Patent Document 1).

  In FIG. 4, 2a is a coil of the starter relay 2, and 2b is a contact that closes when the coil 2a is energized (excited).

  In such an engine starter, for example, when the start operation is performed while the engine is rotating, such as during a restart operation after a start failure or when the driver accidentally operates the starter switch 1 during operation. There is.

  If this erroneous start operation is performed, the pinions 5 may jump into the rotating ring gear 6 and damage them. Therefore, as a countermeasure, the engine rotational speed is measured with a rotational speed sensor as disclosed in Patent Document 1. A technique for detecting and permitting the start operation only when the engine speed is 0 is known (hereinafter referred to as 1 in the known technique).

  However, it is known that a general-purpose rotation speed sensor cannot correctly detect a low rotation speed before stopping the engine (see, for example, Patent Documents 2 and 3).

  Therefore, according to the prior art 1, since there is a high possibility that the engine is still rotating in the undetectable range and the engine is stopped, the pinion 5 and the ring gear 6 (hereinafter referred to as gears). The purpose of protection is not fully achieved.

  On the other hand, as one improvement measure of the publicly known technique, as shown in Patent Document 4, after the detected engine speed becomes 0, after a certain period of time (actually after the engine speed enters the undetectable range). In addition, a technique for permitting the start-up only after the elapse of an estimated time until reaching zero is also known (hereinafter referred to as known technique 2).

JP 2009-197599 A JP 2005-330956 A Japanese Patent Laid-Open No. 9-219906 JP 2009-191653 A

  However, according to the known technique 2, the setting of the waiting time is only a prediction, and depending on the engine, the timing for allowing the start is too early due to insufficient waiting time, or as a result of having a margin, the time is wasted. Occurs.

  In addition, there is a problem that the control and system configuration are complicated by ensuring the waiting time.

  Therefore, the present invention provides an engine starter for a work machine that can reliably prevent damage to gears due to an erroneous start operation and that is simple in control and system configuration.

  As means for solving the above-mentioned problems, in the present invention, an engine, a starter circuit that starts the engine by operating a starter switch, and a hydraulic pump that is driven by the engine and operates a hydraulic actuator circuit An engine starter for a work machine comprising: a pump pressure detecting means for detecting a discharge pressure of the hydraulic pump; and a start control means. The start control means comprises a pump discharge detected by the pump pressure detecting means. The operation of the starter is permitted only when the pressure is not more than a preset value indicating that the engine is almost stopped.

  Here, the “substantially stopped engine” includes not only “completely stopped” of the engine but also “very low speed immediately before complete stop” in which there is no possibility of damage to gears.

  In this way, the pump discharge pressure substantially stops the engine by utilizing the characteristic of the construction machine that drives the hydraulic pump by the engine and the characteristic that the pump discharge pressure is generated as long as the engine is rotating. Since the operation of the starter is permitted only when it is equal to or less than the set value shown, the intended purpose of protecting the gears can be reliably achieved.

  In addition, there is no deviation in the timing of the start permission by setting the waiting time as in the prior art 2, and the control and system configuration are simplified.

  In the present invention, it is preferable that a pressure switch that permits energization of the starter only when the pump discharge pressure is equal to or lower than the set value is provided in the starter circuit as a pump pressure detection unit that also serves as the start control unit (claim) Item 2).

  According to this configuration, since it is only necessary to add a pressure switch to the starter circuit, the system configuration becomes particularly simple, and the cost of the start control system can be reduced.

  In the present invention, as the start control means, a start control relay for opening and closing the starter circuit and a controller for controlling the start control relay are provided, and a pressure sensor is provided as the pump pressure detection means. Only when the pump discharge pressure detected by the pressure sensor is equal to or lower than a set value, the start control relay may be operated to allow energization of the starter.

  According to this configuration, as the pressure sensor and the controller, the pressure sensor originally provided for controlling the machine can be used as it is, or the start control program can be simply added to the controller for controlling the machine. Since only the start control relay is required for the equipment, the system configuration is simpler than that of the known technique 2 and the cost for protecting gears can be reduced.

  According to the present invention, it is possible to achieve the object of preventing damage to gears due to erroneous start operation with a simple system configuration and low cost by utilizing a configuration unique to a work machine.

1 is a system configuration diagram of an engine starter according to a first embodiment of the present invention. It is a system configuration figure of the engine starting device concerning a 2nd embodiment of the present invention. It is a flowchart for demonstrating the effect | action of 2nd Embodiment. It is a system block diagram of the conventional starter.

  An embodiment of the present invention will be described with reference to FIGS.

  The embodiment is applied to a hydraulic excavator.

  In the hydraulic excavator, the hydraulic pump 12 is driven by the engine 11 as shown in FIGS. 1 and 2, and the hydraulic actuator circuit 13 is operated by the pressure oil discharged from the hydraulic pump 12 to perform each operation of excavation, turning, and traveling. Is done. T is a tank.

  In the first embodiment shown in FIG. 1 and the second embodiment shown in FIGS. 2 and 3, the basic configuration of the engine starter is the same as that of the conventional engine starter shown in FIG.

  That is, in the engine starting device, starter circuits B and C each having a starter switch 14, a starter relay 15, and a starter 16 are connected to a battery 17 as a power source, and the starter relay 15 is activated by operation of the starter switch 14. 16 is driven.

  In FIGS. 1 and 2, 15a is a coil of the starter relay 15, and 15b is a contact that closes when the coil 15a is energized (excited).

  A pinion 18 is provided on the rotating shaft of the starter 16, and the engine 11 starts when the pinion 18 meshes with a ring gear 19 provided on the outer periphery of the flywheel of the engine 11.

  In the hydraulic excavator, the hydraulic pump 12 always rotates and discharges oil during engine operation, and as long as the engine 11 is rotating, a pump discharge pressure corresponding to the pump pressure is generated regardless of the rotational speed.

  In both embodiments, the configuration and characteristics peculiar to the hydraulic excavator are utilized, the discharge pressure of the hydraulic pump 12 is detected by the pump pressure detection means, and the start control means detects the discharge pressure of the starter 16 based on the detected pump discharge pressure. It is configured to permit / prohibit operation.

1st Embodiment (refer FIG. 1)
In the first embodiment, the pressure switch 20 serving as both the start control means and the pump pressure detection means is provided in a series circuit connecting the starter switch 14 and the starter relay 15 in the starter circuit B.

  The pressure switch 20 is set to be turned on when the detected pump discharge pressure is equal to or less than a preset value indicating that the engine 11 is almost stopped.

  Here, “almost stop of the engine 11” is not only “completely stopped” of the engine as described above, but also a state of “low speed very close to 0 at the time immediately before the complete stop” with no possibility of damaging the gears. The pressure switch 20 is turned on at a pump discharge pressure (0 or a value very close to it) in this engine state.

  In other words, the pressure switch 20 is turned off in a pressure range where the engine 11 is not almost stopped (a range exceeding the set value).

  Accordingly, even when the starter switch 14 is turned on during engine rotation, the starter relay 15 does not operate and the starter 16 is not energized, so that the pinion 18 does not jump into the ring gear 19.

  That is, it is possible to reliably prevent the gears from being damaged due to the erroneous start operation.

  In addition, there is no deviation in the timing of start permission by setting the waiting time as in the prior art 2, and the control and system configuration are simplified because there is no waiting time control.

  In particular, according to the first embodiment, the pressure switch 20 serves as both the pump pressure detection means and the start control means, and it is only necessary to add the pressure switch 20 to the starter circuit B. Cost reduction is significant.

Second embodiment (see FIGS. 2 and 3)
Only differences from the first embodiment will be described.

  In the second embodiment, as a pump pressure detecting means, a pressure sensor 21 which is an existing facility originally used for pump flow rate control or the like in a hydraulic excavator is also used for starting control, and is detected by the pressure sensor 21. The pump discharge pressure is input to the controller 22 constituting the start control means.

  In addition, a start circuit relay 23 comprising a coil 23a and a contact 23b is provided in a series circuit connecting the starter switch 14 and the starter relay 15 in the starter circuit C, and this start control relay 23 is provided as a controller. 22 is controlled.

  That is, as shown in the flowchart of FIG. 3, when the detected pump discharge pressure exceeds the set value (NO in step S1), the coil 23a of the start control relay 23 is not energized and the contact 23b is opened. Since the relay remains off (step S2), the starter circuit C is disconnected from the battery 17.

  When the pump discharge pressure becomes equal to or lower than the set value (YES in step S1), the start control relay 23 is activated for the first time (step S3), and the starter circuit C is connected to the battery 17.

  Therefore, as in the first embodiment, during the engine rotation, even if the starter switch 14 is turned on, the starter relay 15 does not operate and the starter 16 is not energized, so that the pinion 18 does not jump into the ring gear 19. .

  According to the second embodiment, the same basic operational effects as those of the first embodiment can be obtained.

Also,
(i) As the pressure sensor 21, the pressure sensor provided for machine control as described above can be used as it is,
(ii) As for the controller 22 as well, it is only necessary to add a start control program to the controller for controlling an existing machine, so that only a start control relay 23 is required as a substantial additional facility. Thus, the system configuration is simple and the cost for protecting gears can be reduced.

  In addition, you may provide the pressure sensor 21 and the controller 22 only for starting control.

  By the way, the present invention is not limited to hydraulic excavators and can be widely applied to work machines that drive a hydraulic pump with an engine.

DESCRIPTION OF SYMBOLS 11 Engine 12 Hydraulic pump 13 Hydraulic actuator circuit B, C Starter circuit 14 Starter switch 15 Starter relay 16 Starter 17 Battery 20 Pressure switch which serves as pump pressure detection means and start control means 21 Pressure sensor as pump pressure detection means 22 Start control means Controller 23 comprising the same, start control relay

Claims (3)

  An engine starter for a work machine, comprising: an engine; a starter circuit that operates the starter by operating a starter switch to start the engine; and a hydraulic pump that is driven by the engine to operate a hydraulic actuator circuit. A pump pressure detecting means for detecting the pump discharge pressure and a start control means are provided. The start control means is set in advance so that the pump discharge pressure detected by the pump pressure detecting means indicates that the engine is almost stopped. An engine starter for a work machine, wherein the starter is allowed to operate only when the value is equal to or less than a predetermined value.   2. The starter circuit according to claim 1, wherein a pressure switch that permits energization of the starter only when the pump discharge pressure is equal to or lower than the set value is provided in the starter circuit as pump pressure detection means that also serves as the start control means. The engine starter for the working machine described.   As the start control means, a start control relay for opening and closing the starter circuit and a controller for controlling the start control relay are provided, and a pressure sensor is provided as the pump pressure detecting means, and the controller is detected by the pressure sensor. 2. The engine starter for a work machine according to claim 1, wherein the start control relay is operated to permit energization of the starter only when the pump discharge pressure is equal to or lower than a set value.

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