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A hydraulic control circuit for a radial piston engine with two speeds. The changeover between the speeds takes place through the alteration of the absorption volume, the delivery side being connected to the discharge side with a bypass connection by a valve arrangement for a selected number of engi

A hydraulic control circuit for a radial piston engine with two speeds. The changeover between the speeds takes place through the alteration of the absorption volume, the delivery side being connected to the discharge side with a bypass connection by a valve arrangement for a selected number of engine pistons. The control circuit provides a space-saving way of ensuring that the changeover between speeds occurs smoothly and in such a manner to preserve the individual components as far as possible. To this end, at least one intermediate switching position, in which the delivery side is throttled to the discharge side, i.e. connected by a diaphragm-type arrangement, is provided in front of valve arrangement between the two end switching positions. The valve arrangement is preferably driven such that a valve body can be moved through the intermediate switching position at a controlled speed.

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What is claimed is: 1. Hydraulic control circuit for a hydraulic motor having at least two speeds, with which switching from one speed to another takes place by changing an absorption volume, comprising: a valve arrangement configured to selectively neutralize absorption volumes of selected motor w

What is claimed is: 1. Hydraulic control circuit for a hydraulic motor having at least two speeds, with which switching from one speed to another takes place by changing an absorption volume, comprising: a valve arrangement configured to selectively neutralize absorption volumes of selected motor working chambers, wherein a related intake side for the selected motor working chambers is short-circuited with an outlet side, wherein the valve arrangement has at least one intermediate switching position between two switching positions assigned to the switching process, in each instance, in which the intake side is connected with the outlet side, with throttling of flow medium supply to the motor working chambers to be neutralized, by an orifice arrangement, wherein control of the valve arrangement takes place such that a valve body of the valve arrangement is configured to move through the intermediate switching position in a controlled manner, wherein the valve arrangement includes a first directional valve formed by an infinitely adjustable 4/2-way valve, which produces a connection between an intake of a motor working chamber with an absorption volume not to be neutralized and the intake of the motor working chamber with an absorption volume to be neutralized and between outlets of the motor working chambers, in each instance, in a one end switching position of the 4/2-way valve, and in another end switching position of the 4/2-way valve short-circuits the intake and outlet of the motor working chamber to be turned on and shut off and, at a same time, blocks a remainder of the connection, wherein a control pressure of a control pressure line downstream from an orifice is used to control the valve arrangement, wherein the orifice lies downstream from an inlet directional valve, with which the control pressure line can be connected either with a tank pressure or with an amplifier pressure, and wherein the orifice is configured to be circumvented by a sequential switching valve that switches to circumvent the orifice above a threshold value for the control pressure for the valve arrangement. 2. Hydraulic control circuit according to claim 1, for a radial piston motor having the at least two speeds, with which the switching from the one speed to another takes place by changing the absorption volume, wherein at a selected number of motor pistons, the intake side is short-circuited with the outlet side by the valve arrangement, wherein the valve arrangement connects the intake side with the outlet side, in the intermediate switching position, in which throttling of the flow medium supply to the motor pistons of the motor piston group to be neutralized with respect to an absorption volume of the group takes place, by the orifice arrangement. 3. Control circuit according to claim 1, wherein an initial pressure through the infinitely adjustable pressure valve is used to control the valve arrangement. 4. Control circuit according to claim 3, wherein the control pressure of the valve arrangement is configured to be changed ramp-like. 5. Control circuit according to claim 3, wherein the control pressure of the valve arrangement is configured to be changed progressively. 6. Control circuit according to claim 1, wherein the valve arrangement includes a second directional valve, with which, in an operational state in which the 4/2-way valve is in its other end switching position, flow medium can be supplied into shunted input and output ports (C, D). 7. Control circuit according to claim 1, wherein the valve bodies of the first directional valve and a second directional valve are arranged concentric to one another. 8. Control circuit according to claim 1, wherein the valve body of the infinitely adjustable 4/2-way valve includes a valve piston that has the control pressure applied to it, counter to a pressure spring, control edges of which piston are provided with grooves that form the orifice arrangement. 9. Radial piston motor with a control circuit according to claim 1, wherein the valve arrangement is integrated into the motor housing. 10. Radial piston motor according to claim 9, wherein the valve arrangement is structured as an insertion module. 11. Hydraulic control circuit for a hydraulic motor having at least two speeds, with which switching from one speed to another takes place by changing an absorption volume, comprising: a valve arrangement configured to selectively neutralize absorption volumes of selected motor working chambers, wherein a related intake side for the selected motor working chambers is short-circuited with an outlet side, wherein the valve arrangement has at least one intermediate switching position between two switching positions assigned to the switching process, in each instance, in which the intake side is connected with the outlet side, with throttling of flow medium supply to the motor working chambers to be neutralized, by an orifice arrangement, and wherein control of the valve arrangement takes place such that a valve body of the valve arrangement is configured to move through the intermediate switching position in a controlled manner, wherein the valve arrangement includes a first directional valve formed by an infinitely adjustable 4/2-way valve, which produces a connection between an intake of a motor working chamber with an absorption volume not to be neutralized and the intake of the motor working chamber with an absorption volume to be neutralized and between outlets of the motor working chambers, in each instance, in a one end switching position of the 4/2-way valve, and in another end switching position of the 4/2-way valve short-circuits the intake and outlet of the motor working chamber to be turned on and shut off and, at a same time, blocks a remainder of the connection, wherein the valve arrangement includes a second directional valve, with which, in an operational state in which the 4/2-way valve is in its other end switching position, flow medium can be supplied into shunted input and output ports (C, D), wherein the second directional valve includes an infinitely adjustable 3/2-way valve that feeds a control pressure into a supply circuit for the neutralized motor working chamber. 12. Hydraulic control circuit for a hydraulic motor having at least two speeds, with which switching from one speed to another takes place by changing an absorption volume, comprising: a valve arrangement configured to selectively neutralize absorption volumes of selected motor working chambers, wherein a related intake side for the selected motor working chambers is short-circuited with an outlet side, wherein the valve arrangement has at least one intermediate switching position between two switching positions assigned to the switching process, in each instance, in which the intake side is connected with the outlet side, with throttling of flow medium supply to the motor working chambers to be neutralized, by an orifice arrangement, and wherein control of the valve arrangement takes place such that a valve body of the valve arrangement is configured to move through the intermediate switching position in a controlled manner, wherein the valve arrangement includes a first directional valve formed by an infinitely adjustable 4/2-way valve, which produces a connection between an intake of a motor working chamber with an absorption volume not to be neutralized and the intake of the motor working chamber with an absorption volume to be neutralized and between outlets of the motor working chambers, in each instance, in a one end switching position of the 4/2-way valve, and in another end switching position of the 4/2-way valve short-circuits the intake and outlet of the motor working chamber to be turned on and shut off and, at a same time, blocks a remainder of the connection, wherein the valve arrangement includes a second directional valve, with which in an operational state in which the 4/2-way valve is in its other end switching position, flow medium can be supplied into shunted input and output ports (C, D), wherein the second directional valve includes a 2/2 switching valve that feeds system pressure into a supply circuit of the shut-off motor working chamber. 13. Hydraulic control circuit for a hydraulic motor having at least two speeds, with which switching from one speed to another takes place by changing an absorption volume, comprising: a valve arrangement configured to selectively neutralize absorption volumes of selected motor working chambers, wherein a related intake side for the selected motor working chambers is short-circuited with an outlet side, wherein the valve arrangement has at least one intermediate switching position between two switching positions assigned to the switching process, in each instance, in which the intake side is connected with the outlet side, with throttling of flow medium supply to the motor working chambers to be neutralized, by an orifice arrangement, wherein control of the valve arrangement takes place such that a valve body of the valve arrangement is configured to move through the intermediate switching position in a controlled manner, wherein the valve arrangement includes a first directional valve formed by an infinitely adjustable 4/2-way valve, which produces a connection between an intake of a motor working chamber with an absorption volume not to be neutralized and the intake of the motor working chamber with an absorption volume to be neutralized and between outlets of the motor working chambers, in each instance, in a one end switching position of the 4/2-way valve, and in another end switching position of the 4/2-way valve short-circuits the intake and outlet of the motor working chamber to be turned on and shut off and, at a same time, blocks a remainder of the connection, wherein the valve arrangement includes a second directional valve, with which, in an operational state in which the 4/2-way valve is in its other end switching position, flow medium ca be supplied into shunted input and output ports (C, D), wherein the second directional valve includes control pressure of the infinitely adjustable 4/2-way valve applied to it and is controlled by it.